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Test Gear - The R-390A Frequently Asked Questions Page

1. Interesting have a Triplett 3444 not the A model which is a darned good machine However at the moment have nothing which shows me how and where to adjust the various voltages The selenium rectifiers in it are getting very leaky and want to change them before they take out a transformer Date Tue 26 Jun 2007 01 07 27 0400 From Tracy Fort lt beerbarrel cox net gt Subject RE R 390 Tube testers hear ya Scott had a TV 7b u It has issues and my tv 2 did not find the older that get the harder it is to deal with stuff in tight areas sold it on Ebay and kept my others have a BK 650 and use it quite often It is super easy to set up and test a tube also have the optional adapterwith it that allows you to test older tubes All things considered all of the TV testers are good think that it comes down to personal preference Date Tue 26 Jun 2007 07 04 30 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 Tube testers The whole issue of having a full set of tech manuals for both maintenance and full blown rebuild is a big issue on the commercial stuff Some companies test gear page 149 published that kind of stuff and a lot didn t Even the military was not quite as good as they should have been on some test gear The compelling argument in favor of the military testers is that you are more likely to find both the data and the parts to keep them running Date Tue 26 Jun 2007 22 38 37 100
2. found some emails in my notes about this some time ago gt gt Speaking of signal generators how does the URM 25J gt gt stack up against the others mentioned gt gt My guess is about the same gt gt Is it substantially better than the D model Just what are the differences gt Can t tell you but my notes on the URM 25 include the following messages gt assume that more attenuation stages means an additional step in the gt output attenuator do not have pictures with enough clarity to see if this is true or not gt gt gt just bought a URM 25 generator from Fair Radio checked unit It looks gt gt complete with all the adapters manual etc When was looking for one they gt gt disappeared off the Web and epay My unit has 2 different tags on it the gt gt front panel has a URM 25D with new screws and the case has a URM 25J gt gt 19687 Is there anyway of knowing which one have and what version is a gt gt URM 25J gt gt The tag is attached to the front panel gt gt The front panel is attached to the guts gt gt That is what makes the model gt gt The case is just there to keep the dust out gt gt gt gt Ok so some one droped a D model into a J case gt gt Ah the wonders of interchangeable parts gt gt The J version is the 9th or 10th version test gear page 366 gt gt gt gt lt lt thought the URM 25J was a URM 25D with a different accessory or gt gt two At
3. increased the filament voltage to 6 3VAC and the probed started heating again however it appeared that my AC voltage readings were off considerably Figuring the EA53 was failing shelved it waiting to find either a 2 01C probe or an affordable EA53 recently noticed an auction for a probe set for the 410B but it appeared to have the AC probe from an ME26D U emailed the owner and asked if he happened to have any EA53s and he did however he said it sounded like something else was wrong with the meter instead of the diode started checking around on it again opened the probe top and fed the AC input via a regular silicon diode At 6Ocps the results were exactly the same as the EA53 With the probe still open and the diode powered checked whether the EA53 was working and confirmed with my scope that it was functioning as a half wave rectifier It appeared something further upstream from the probe might be wrong then happened to think of something My test voltages were coming from a variac which was being fed with an isolation transformer Since know that when measuring line voltages it is not proper to connect the ground but only use the probe tip was using that method to get sample voltages form the variac It then occured to me that was checking the voltages across an isolated circuit connected the ground clip and the meter again start reading correctly or nearly so After running through the calibration steps the
4. one is for the 505 505 A and through the 505D model The 505 has a battery compartment on the front and three binding posts All the others have NO battery and one binding post ground My 505D is warming the corner of the dining room just now was reminded of how nice a meter it is and dug it out for a little excercise Date Sat 09 Mar 2002 19 47 26 0800 From eengineer erols com Subject Re R 390 Re TS 505C U Manual Yes Itis on the ADDENDUM CD From Scott Barry Clyde B lt cbscott ingr com gt To R390 E mail lt R 390 mailman qth net gt Date Mon 11 Mar 2002 16 03 52 0600 Subject R 390 ME 26 Meter problem update Well got the meter movement fixed in the ME 26D U Without a welder milling machine etc decided to try with the available tools mounted to the meter upside down to a piece of wood with some neoprene washers to protect the finish Using two large screwdrivers was able to apply pressure to two opposing slots and push the ring around to its unlocking position After fixing the movement straightening one of the bends such that the needle moved about 0 020 away from the meter face started putting it back together Simple just push the locking ring back into position with the two large screwdrivers Was working great until one screwdriver slipped causing me to loose my hold on both screwdrivers The problem is both hands were applying pressure towards the meter back When my
5. tom N3LLL Date Sun 15 Feb 2009 19 16 11 0500 EST From Richard W Solomon lt w1ksz earthlink net gt Subject Re R 390 test equipment question One reason the Wavetek is so cheap is that it is a 75 ohm output device Date Sun 15 Feb 2009 20 15 58 0600 From lt wb5uom hughes net gt Subject Re R 390 test equipment question Bob probably said it best Those that work on this older gear use what WE desire and what WE have Being able to use what you have at hand is what is important think Now certainly dont know it all and probably am lacking in the complete abilities of some of the equipment am lucky enough to have If you call being in business for yourself lucky that is Watching someone wanting to measure or test a piece of equipment and saying they can t do it for one reason or another and then showing them that they CAN do it with what they have is always fun Yes my IFR Com 120C is better than the Cushman CE 4 started with in 1985 But its still what you can do with it thats important Date Sun 15 Feb 2009 20 45 58 0600 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 test equipment question test gear page 186 I ve used the IFR 1200S and currently carry the IFR Com 120B Pretty good stuff the 1200S does SSB The latest offerings from IFR are junk Looks like they have been bought out by Aeroflex Another good one is the earlier IFR 500 Small and lighter chea
6. 7 many times that worked just fine in the radio Of course what circuit it is being used in makes a difference also ymmv As some of the older wiser gurus have test gear page 156 said over the years the best tubes tester many times is the receiver it is being used in Date Fri 10 Aug 2007 21 57 40 0700 PDT From Perry Sandeen lt sandeenpa yahoo com gt Subject R 390 Tube extenders One of the useful items for R390A maintenance is a tube extender Unfortunately they rarely show up on epay and when they do they tend to get very pricey In compiling info for the Y3K manual ran across a nifty adapter in the Army manual TM 11 856A as figure 54 Fabrication of tube test point adapters It is both simple clever and cheap You use two matching 7 or 9 pin tube sockets The bottom one is turned upside down with the 18 gauge wire threaded thorough the tube pin holes as well as being soldered to the socket tabs The manual is available from the R390 site If one doesn t have a copy of this recommend you D L it There are several improvements to what is in the Navy Y2K version in regards to AGC circuit info as well as test jigs and two pages on the color codes used on the resistors and capacitors Also some very nice B W pictures of many modules don t have a web site but will email a TIFF image to anyone who wants it for personal use or to post it It s also going to be added in the additional chapters of Y3K along with other t
7. Date Fri 14 Jan 2011 13 32 07 0600 CST From nryan mchsi com Subject Re R 390 Signal Generators et al This is exactly the same setup have and I m very pleased with it Sure the AN URM 25D is a pain to zero in at higher frequencies due to play in the gears Has anyone tried eliminating the slack Otherwise my SG ain t broke so am reluctant to fix it By sheer luck at a hamfest found an exact replacement tuning knob fitted with a crank handle which greatly speeds up changing frequency The TS 505D is a joy to use always get a kick out of nudging up the diode load reading with each alignment iteration between coil and cap on the RF deck The analog readout is very responsive and quick to read Another part of the fun is the retro aspect stepping forward into the past if you will operated R 390s in the USASA as a kid and later in life got into these receivers as a result of that experience Date Fri 14 Jan 2011 15 44 57 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 Fluke 6060a an or hp 8640b gt have both a Fluke 6O60A AN and 2 HP 8640B Any opinions on test gear page 241 gt one which should keep The 6060 is one of the better synthesized generators although it still cannot match an 8640B when close in phase noise is a primary concern As with all computer controlled generators it is very convenient to change settings quickly and you can coordinate automated test scheme
8. Subject Re R 390 HP 8640B vs HP 8654A 8655A 11710B Tucker had a truckload of them between them and e Bay there were a lot of them got one NIB for about 50 was not too impressed with the design Date Mon 10 Jan 2011 00 26 43 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP 8640B vs HP 8654A 8655A 11710B It s just a 50 MHz oscillator a mixer a one transistor post mixer amp and some filtering and switching there are also 5 MHz and 1 MHz outputs divided down from the 50 MHz oscillator but they are not pertinent to the primary function of the unit Their big claim to fame was that the conversion gain loss was within 1 dB over the full frequency range so you can rely on the output level test gear page 231 set by the 8640B Not always an easy trick with a mixer output covering 10 kHz to 11 MHz and input levels from 0 dBm to 110 dBm reduced the amplifier noise a little by replacing the single transistor RF amp with a two transistor feedback amp in one of mine but that by itself made very little difference the noise added by the 11710B is mostly from the 50 MHz oscillator as mentioned in a previous message replaced the oscillator in the one modified with 10 MHz from the shop 10 MHz distribution amp which can be fed by a GPSDO or a Rb source and a 5x multiplier with appropriate filtering That one is nice and quiet as well as holding the mixer LO frequency to the same lt ppb
9. The HP 606B has an all solid state 300 volt 200 volt and 25 6 volt regulated power supply It also has an all solid state calibrator A2 assembly The rest is TOOBS used one in the avionics business for years and have one in my hamshack now Date Mon 17 Jan 2005 20 32 24 0500 From Michael Murphy lt mjmurphy45 comcast net gt Subject Re R 390 HP 606 vs URM 25 test gear page 351 have a 608F which got from work FREEBIE What a glorious monster also have a late model 606B 1972 Vintage that just got this spring at the local junk store It had busted meter glass and offered him 35 for it Short story dragged it home and it fired up It is in the modern HP white ivory color not the grey or tan and let me tell you it is one fine piece replaced the glass using an old fashioned glass cutter on an old pane Never having had this kind of gear in the shack before now feel spoiled This truly is the golden age of test vintage equipment Date Wed 19 Jan 2005 12 47 10 0800 From David Wise lt David_Wise Phoenix com gt Subject RE R 390 HP 606 vs URM 25 got mine at eBay for around 250 less shipping It was partly operational and missing a couple of knobs was able to replace them with generic ones from RS with some judicious drilling and gluing Thank goodness the original skirt was still there felt that the Band and FM Deviation had too much detent It s easy to soften it they use multi
10. almost never use the TV 7 though once compared mine on a number of tubes with the 600a and it indicated about the same Of course a tube tester is mild reassurance that a tube is ok and can find tubes with open filaments shorts and low emission readily Most testers do about the same unless you get into testers with other kinds of metering different than the ones that am familiar with always wanted to try a Hickok 539 I think that s the number but they seem to find buyers with more money than sense Maybe l Il stumble across one for a reasonable price someday Best regards Dan Date Fri 05 Aug 2005 13 19 20 0400 From James A Andy Moorer lt jamminpower earthlink net gt Subject Re R 390 Tube Tester have an EMC 215 You can get them for 10 25 you know where Many tube nuts poo poo them as being crass cheapo commercial units but have yet to find a case where it reads anything different from my TV 7 or my TV 2 The construction on the inside is not very rigorous for instance they use the infameous flying joint soldering technique in a couple of places A few test gear page 125 minutes with the soldering iron will put all these right The list of the tubes they test is quite complete To do some of the transmitting tubes you need an extension box which is a bit harder to find have only found a couple of tubes they won t test and nobody else tests them either like the 9556 UHF triode Date Fri 5
11. had a chance to do a little more testing It seems the diode is only pulling about 11 microamps depending on the accuracy of my meter which is not correct should be 500 microamps I m seeing approximately 6 3VAC at the socket and the tube itself has slight resistance across its filament so must have something else going on Looks like another project Date Sun 26 Mar 2006 16 20 25 0500 From Mort Denison lt bmg50pa suscom net gt Subject R 390 Central Electronics Model B Signal Slicer w R 390A Has anyone ever connected up one of these to an R 390A I ve got the one with the built in Q multiplier and am curious if it s possible to hook it up without having to modify the receiver too much Or would it not be worth the trouble Date Sun 26 Mar 2006 21 42 33 0600 From Barry lt n4buq knology net gt Subject Re R 390 HP410B rectifier tubes Did some more digging With the cover off can measure the filament voltage for the EA53 while it is in circuit had to crank the resistor quite a bit farther up to get 6 3VAC across the filament This did cause the probe to get really warm like it used to however the probe still doesn t check AC properly low reading did some checking in the manual It states to check the resistance below the ballast tube with the ballast tube removed from the circuit This should produce 4 to 6 ohms If it doesn t most likely something has been shorted assume it means something has
12. worked up calibration points for a BC 221 with the mixing up into low microwave and found maybe half of them existed Got me really fine calibration points at close intervals good for a good score in the old ARRL Frequency Measuring Tests Date Sun 09 Jan 2000 17 45 29 0600 test gear page 291 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Signal generator connection questions gt set the frequency of the URM 25 D to 455 Hz exactly without a freq counter Hmmm sounds like me after the hammer and shotgun episodes with a couple of previous counters If you have a little digitally tuned receiver like a RS DX 440 etc First tune it 10 000 MHz or whichever one you can receive and turn the BFO on Zero beat the BFO with WWV Now tune the receiver to 910 KHz and then zero beat the output of the signal generator to the receiver using the second harmonic of 455 KHz while you tune the signal generator It ll get you more than close enough probably with a few cycles got real good at harmonics for a while One thing that you need to remember First never use the Set Carrier to 10 pot to raise or lower the output level of the signal generator The output frequency varies somewhat as that control is moved You need to be real consistent at setting it to 10 each time you change the frequency of the signal generator with the main tuning dial You do this with the microvolts pot set to max After you set the
13. 0400 From Gord Hayward lt ghayward uoguelph ca gt Subject Re R 390 Ramblings on Calibration High level calibration for the 390a is certainly worth while Last week was debugging a crystal oscillator and used the 390a as the monitor It was as stable as my crystal for several hours and the frequency was dead on The problem with the crystal was mode hopping as the water on the gold electrode surface evaporated know this sounds strange but use the crystals as bio sensors This series of oscillators is to measure blood clot busting drugs such as t PA by growing a clot on the crystal and watching the frequency shift and series resistance change as the drug eats the clot Date Thu 12 May 2005 18 43 09 0700 PDT From W Li lt wli98122 yahoo com gt Subject R 390 Re little things Over the years have made some little additions to my trio of R 390A s that may be of use to you guys Most are obvious and simple about my speed nowadays Most are not original with me but have been mentioned in earlier posts through the years lt snip gt l 177 5814A accessory Those of us with I 177 tube testers know that you can not check 9 pin miniature tubes without the MX 949U accessory Of course you can make up your own with all the jacks and leads but all wanted today was to check 5814A s so made up a simple plug in for socket E using the octal male plug with its metal mounting plate scrounged from a surplus octal rel
14. 13 Feb 2009 23 50 25 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 test equipment question I m no fan of the military signal generator but if it s working properly it will get you through particularly if you can trust your counter third or fourth the recommendations of the HP 8640B You can get brass replacements for the nylon gear that shrinks In any event rarely use a sig gen for troubleshooting rather for calibrating and optimizing in particular the RF gain happen to like using a scope for most of my measurements but YMMV A Tek 465B is way overkill but nice to have prefer the comparable HP scopes personally 1740 series but I like Teks just fine see no need for an audio oscillator as long as the sig gen has an internal modulation oscillator If you feel the need for an RF voltmeter get better yet build an RF probe to use with the Heath VTVM don t have one and have no idea what I d do with one but then use a scope for that The last thing I d like to address is the philosophy of radio service Many of the comments posted so far seem to advocate a shotgun approach don t There are certain components in most electronic products that are either failure prone or that have devastating consequences if they fail the infamous C553 in 390As is a prime example of the latter all of the tubular capacitors in SP 600s are good examples of the former For the 390 and 390A
15. 20 Feb 2010 14 34 31 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 HP 8640B Question Having looked on that Evil Place see several up for auction with a bunch of pictures One in particular shows zeroes across the display AND the switch on the rear is set to INT wouldn t place a bid under any circumstances Date Sat 20 Feb 2010 16 07 59 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP 8640B Question gt One in particular shows zeroes across the display AND the switch on the gt rear is set to INT The relevant INT EXT switch is on the front it selects the input to the counter The INT EXT switch on the back determines whether the 8640 looks to an internal or external oscillator for its time base That said most 8640s I ve seen that read all zeros don t do so because the counter input is set to EXT but rather because someone once used them to count external signals and fried the counter That is the single most common 8640 problem I ve seen So much so that advise folks NEVER to use the 8640 s external counter It comes with a BNC cap leave it there Note that the military Option 323 units do not have an external counter input for this very reason Best regards Don Date Sat 20 Feb 2010 16 41 30 0600 From Mahlon Haunschild lt mahlonhaunschild cox net gt Subject Re R 390 HP 8640B Question Indeed that ext counter input is spec d from 100 mVrms to 1 3Vrms T
16. 26 Jun 2007 14 51 48 0400 From David C Hallam lt dhallam rapidsys com gt Subject RE R 390 Tube testers have a tube tester too and use it for one thing Occasionally run across some audiophile audiophooles type tubes and sell them on eBay Everyone wants to know what they test on a tube tester So test them and put the reading in the auction For my own use keep a stock of spare tubes and substitute when want to know if a tube is good or not Date Tue 26 Jun 2007 15 05 27 0400 From Tracy Fort lt beerbarrel cox net gt Subject RE R 390 Tube testers have a better idea Bring all your tube testers to my house I ll sell them on Ebay while you guys learn all about tubes from a book Date Tue 26 Jun 2007 15 19 02 0400 From Tim Shoppa lt tshoppa wmata com gt Subject Re R 390 Tube testers Seeing how the 12BE6 is a heptode and in a AA5 used as both an oscillator and a mixer not too surprising that the tester got stumped by it Most likely it wasn t oscillating and the tester used a grid not for oscillation for its test was test gear page 154 recently working on SPICE models for heptodes and no tube book gives useful information for modeling Had to do some 3 dimensional curve tracing Date Tue 26 Jun 2007 15 51 34 0400 From flood Krohne com Subject R 390 And the tube tester thread goes on My TV 7U D came to me as NOS It was saved from the junk pile never having
17. Date Sun 15 Feb 2009 01 56 48 0000 UTC test gear page 182 From odyslim comcast net Subject Re R 390 Test Equipment agree with Pete recently had an R 390A that was so deaf the calibrators could not be heard Slowly tuning the bands found the faintest carrier it was WWCR I can usually hear it with no antenna Anyhow was able to bring the radio up using that carrier and the alignment tools only The radio was put together from spare parts and items bought on ebay It was a pile when started Totally deaf when completed Everything was out of whack My URM 25 was bought refurbished from a gentleman on this list It works very well with a voltmeter for R390xx gear do also use a frequency counter as an option It is home brew Date Sat 14 Feb 2009 18 13 57 0800 PST From wli lt wli98122 yahoo com gt Subject Re R 390 test gear hang a small commercial freq counter on the high output RF connector on my URM 25F Makes alignments a lot easier on me Of course if and when one wants to to measure SN N then you have to cap that jack Date Sun 15 Feb 2009 14 51 13 0500 From Patrick lt brookbank triad rr com gt Subject Re R 390 test equipment question To me the best Frequency Generator that have is a 0 464 SRC Synthesizer Electrical Frequency works from 2 to 34 MCS is solid a a rock and plenty of adjustable power to use with a small antenna A little big a heavy rack mountable but very rel
18. FS I ve got a couple that the cal sheets show at about a quarter of a percent picked these when they were surplused from Onan up North bought them all The average cost on them was only about seven or eight dollars apiece plus shipping One of the main reasons that a lot of the older lab gear is being sold off by companies is that the newer gear is so much easier and faster for the average person to use There is a lower chance of operator error and resulting incorrect readings In addition the calibration of an analog equipment is very slow and tedious You can easily spend a couple of hours on with the HP meters mentioned above or on just one of the Weston portable lab meters A lot of the new digital lab gear is calibrated via software Type a couple of commands and it s done perfectly Some of this gear can actually monitor it s calibration and will shut down if it s outside of certain parameters A lot of it has an internal clock and will shut down if not run thru the calibration checks every x period of time When you consider that a lot of places have regular calibration rituals that they follow every 3 or 4 or 6 months over the course of a few years the calibration costs and labor for old gear easily exceeds the value of the gear itself Over the last few years I ve been putting more effort into picking up and restoring test equipment that have than looking for new radios to ad to the menagerie Old test gear can be a lot of
19. From Barry lt n4buq knology net gt Subject Re R 390 HP 410Bs and AN URM 25s Any chance of posting pictures of that 410B anywhere I d like to see that one Date Thu 1 Mar 2012 14 08 32 0500 EST From ToddRoberts2001 aol com Subject Re R 390 HP 410Bs and AN URM 25s Know of some folks who are buying used URM 25s to strip the tuning capacitor out of for crystal radio aficionados The variable capacitors are very high quality with silver plated vanes and highly sought after by crystal radio builders for their high Q One of those capacitors recently sold for 202 on Ebay Date Thu 01 Mar 2012 14 24 54 0500 From rbethman lt rbethman comcast net gt Subject R 390 HP 410Bs and AN URM 25s This indeed went the way felt that it would So am going to put it on my site for download with regard to the AN URM 25s All info regarding the HP 410s is available on lt www kiss electronics com gt Give me a chance to grab the URM 25 parts and refurbish procs combine them into one text file and get it on my site for any and all to download The number of requests has already gone over 8 or so only expect this to keep climbing Date Thu 01 Mar 2012 14 41 34 0500 From rbethman lt rbethman comcast net gt Subject R 390 AN URM 25 info have JUST uploaded the parts and procedures in one document It may take an hour before it s available depending on Comcast s servers lt http nome comcast net rbethman Parts
20. From Curt lt cptcurt flash net gt Subject Re R 390 AN URM 25s In the Army cal manual for the TM 1170 Wavetek 3002 there is described a test wand used to validate the leakage level The attenuator goes down to 138dBm Date Thu 01 Mar 2012 15 21 43 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 AN URM 25s This may be so will only explain that with my AN URM 25D on not connected and about 3feet away from a closed Kenwood R 2000 with nothing connected to the SO 239 and NO cable on the AN URM 25D was able to pick up carrier and S Meter deflection This was with the output dialed to the minimum on the Sig Gen So the leakage is real Both were on separate circuits and both had a separate ground Hence my commentary and my intent If want to begin sniffing have an HP 312A Frequency Selective Voltmeter However based on the described above observation I m going with the extra RF seal Date Thu 01 Mar 2012 15 42 04 0500 test gear page 380 From Curt lt cptcurt flash net gt Subject Re R 390 AN URM 25s Yes don t think your observations are unique As Trish noted it takes a lot of effort to really seal up something at that RF level I m sure the braid seals will help Former life as a Tektronix field engineer had the opportunity to support several well equipped Rx development labs in the area The efforts they took to get isolation were pretty remarkable Screen rooms f
21. From Scott Bauer lt odyslim comcast net gt Subject R 390 after all these years tube checker story After all these years have finally found a bad tube that my TV 7 passed had been running this radio for quite some time about 4 months When came down into my radio kingdom this radio was running but dead quiet It is tuned up with 4 others to the Global HF System so knew automatically there was something wrong The others were receiving traffic The normal troubleshooting produced nothing decided to check the tubes as stated above it has been a while All tubes tested above specs Swapped the IF module still dead Audio module still dead had already checked the cables from the multi coupler The ballast was good the OA2 was good 150 volts should have checked out one specific tube before swapped out those modules as after doing it remembered having this problem before It was V401 but it failed the test on the same tester in the past swapped it out anyhow and bingo problem solved That along with a few others will make a radio deader than a door nail Know most of you already know this am just passing my learning experience am always thrilled when am able to solve problems without getting the iron out From Les Locklear lt leslocklear cableone net gt Subject Re R 390 after all these years tube checker story have had tubes that failed the minimum test not the shorts test in my old TV
22. I d feel better by using more screws along the edge with more L brackets than just using an oil can style cover where the edge contacts was by pressure and fit Then the conductive Scotch may help gt Maybe some ferrite beads on all of the wiring that feeds into gt the casting at the bypass caps meter leads etc Ferrite beads here are just palliative that s mostly ineffective A few ohms maybe 50 series reactance where thousands are needed The feed through capacitors with only a few thousand PF need to be replaced by 0 1 feedthrough papers with zero shunt inductance or metal packaged feed through L or Pi type filters don t know if they can still be bought but the inductance needs to be inside its own shield to be worth the bother One might add an RF choke and second feed through filter capacitor on a closed box mounted over the existing feedthroughs Date Sat 16 Dec 2000 11 30 56 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 URM 25 Stability gt I d class that as a conductive gasket Yes that d be a good description never did know what the stuff was called gt I d just almost prefer a knife edge than the gap imposed by the screen wire It seemed to me that the dead flat and mated surfaces would be better two Maybe the conductive gasket is cheaper than quality machine work gt gt Maybe some ferrite beads on all of the wiring that feeds into gt gt the casting at the bypass caps meter lead
23. It s finding replacements that s the killer gt Its been ages since did one but if the old grey matter is still gt functioning there was room for the more recent film types There s not a whole bunch of room to work with inside the cavities of the attenuator of the D model The design is totally different for the F model and it s a lot easier with more room Actually just about everything is easier on the F model The original resistors were high quality and stable 1 8 watt dipped and sealed deposited film carbon resistors of non standard values with a negative temperature coefficient Tough as hell to find gt Those are available in 1 tolerance and can be fine tuned to exact gt values with a diamond scribe I m not sure of how stable they would be long term but that s an interesting idea I d imagine that sealing the resistor body with varnish or something would be a good idea to keep the humidity out and improve the stability a bit after massaging the value I ve never seen anything on doing this before I d like to hear from anyone that has information and experience with doing it gt Even off the shelf values should be close enough for government work gt Who cares if it is 499 vs 495 or 61 9 vs 61 8 etc test gear page 293 Me for one lt grin gt If wasn t worried about some degree of accuracy in my test gear I d be using one of my Conar 280 s or an Eico 322 or something similar for my primary signal generator rat
24. Three 6AK6 s also test gear page 59 show shorts on the same switch position NOS 6AK6 s test good Also came up with 3 weak 6C4 s Doesn t that seem unreasonable or is this a common failure mode did have a similar experience in testing tubes in a 392 which turned out to be shorting at the tube tester socket The later TV 7 s maybe just the D s and later have ferrite beads on each lead going to the tube socket terminals They tend to crowd on the 7 and 9 pin sockets as they back right up against the bare terminals at least in this one Also the 7 pin socket in particular tends to get loose and move around secured all that last time and I m getting short free readings on new and other old tubes Could something be so wrong in this rx to damage the tubes Or is it more likely that somehow my TV7 D U be overly sensitive on one position Shorts show only on switch position 3 While I m waiting for some advice I ll go ahead and test the plugins and pull the audio and IF modules Date Sun 30 Sep 2001 11 57 43 0400 From Norman Ryan lt nryan intrex net gt Subject Re R 390 R390A tube chart amp PUZZLEMENT had a similar issue with my TV 7D Seems the shorts test adds wear to its selector switch If you pull your tester out of the cabinet you may find as did some powdery stuff on the ceramic wafers that must be contributing to overly sensitive shorts readings used compressed air to blow the stuff out of said s
25. What tester would serve my needs Date Fri 2 Feb 2001 06 05 39 EST From G4GJL aol com Subject Re R 390 Tube testers think the radio itself is the best tester Use well worn tubes in the PTO BFO and RF stages Then juggle what remains in the IF to get the least noisy tubes closest to the Antenna always use brand new tube as a control to ensure that am not unwittingly reducing the sets performance as move the tubes around Sometimes the control gets left in the set as the weakest tube is rejected Sometimes you will find that the tubes in the set when re arranged give adequate performance BTW adequate could mean acceptable audible to specification contest grade etc etc depending upon your personal criteria test gear page 262 At the end of the day it does not matter what measurements on a 30 year old tube tester tell you You cannot connect an antenna and speaker to a tube tester Only performance in the real radio counts Date Fri 2 Feb 2001 06 43 42 0500 From Barry Hauser lt barry hausernet com gt Subject Re R 390 Tube testers As they say in the Hertz commercials Not exactly gt think the radio itself is the best tester Expensive way to test for shorts If you try a tube and the radio smokes discard tube Also why you do the shorts test on a tube tester before the quality Replacement multivoltage transformers for TV 7 s and Hickok commercial testers are not on the rack at Radio Sh
26. back in 1970 or the probe alone was 70 Now for a little TRIVIA Did you know that Collins Radio assigned a Part Number to this VTVM The HP 410C also has a Military Designation of ME303A U According to the FEDLOG Dated 1 Sept 98 the governments last shown procurement was 532 00 NOW FOR THE REST OF THE STORY The HP 410C Probe 11036A is also known as a MX 8881 U and was last procured for 364 78 a piece All branches of the armed services used or still use this probe It is also part of some specialized Test Set such as the AN TYA 23 and 27 and shows usage on a wide range of weapon systems from the Poseidon Submarine to the USAF F 111 aircraft The HP AC Probe 11036A is usable to 300 VAC 20 Hz to 700 MHz Accuracy 3 GOOD DAV Date Wed 16 Oct 2002 19 47 09 0400 From rbethman comcast net Subject Re R 390 TS 505 and TS 352 The TS 352 is NOT a VTVM It is all solid state The TS 505 series IS a VTVM Date Thu 17 Oct 2002 12 39 25 0400 From rbethman comcast net Subject Re R 390 TS 505 and TS 352 The biggest point is that the TS 352 IS NOT a VTVM and does NOT have the same high input impedance Therefore it WILL NOT do the same job as a VTVM I can t find the PDF but someone posted a link to manuals awhile back There was one there Subject Re R 390 TS 505 and TS 352 From Richard McClung Dielectric spx com Date Thu 17 Oct 2002 10 01 44 0700 The TS 505D U TM is on a CD that one of the list
27. believe that the DA 121 U was the Dummy Load that was supplied with the military AN URM 25 AN URM 26 Series Signal Generators It may have been a supplied accessory with one or both signal generators Hard to believe that it has been over 30 years since last used on of these just looked at my FEDLOG and it was still lasted as of Mar 05 with two part numbers The DA121U and ENTRON INDUSTRIES LP FOREST HILLS N Y Part Nr 157C4 National Stock Number 5985 00 557 5717 Last procurement shown is 12 86 at 169 58 The DA 121 U is a 50 Ohms 0 5 Watt 0 50Mhz Dummy Load recall that the URM 25 had four or five different types of attenuators and a Dummy Antenna Load in the lid These were a small rectangular aluminum box with a cover secured by 4 screws Each one had a BNC Input and Output Connector with the exception of one that had a BNC Input and a Black and a Red Wire with alligator clips for the Output also think that hmay have seen these in a tubular metal configuration but don t hold me to that The TM T O or NAVSHIPS Manual on these generators had pictures and electrical diagrams I ll bet if you go over to BAMA you may find the info that you are looking for Date Sun 3 Sep 2006 12 55 40 0400 From David C Hallam lt dhallam rapidsys com gt Subject R 390 DA 121A U In regards to my recent post about what is a DA 121A U dummy load It is part of Electronic Maintenance Kit MK 288 URM On the LOGSA web site there is a D
28. calibrators redundant By the way if you run into one of these old calibrator units in good working condition purchase it they are very handy to have went working on old brontosaurus transmitters test gear page 224 Date Thu 5 Aug 2010 18 34 12 0400 EDT From frankshughes aim com Subject R 390 HP spectrum analyzer question would like to obtain an HP spectrum analyzer to use on my R 390A and R 390 plus whatever other ancient boatanchor devices come to my workbench in the future Trouble is unlike the choice for a generator 8640B there are too many HP Spectrum analyzers on the E place for me to pick from can eliminate most just by the frequency spread but am missing the knowledge and experience as to which HP might be a relatively trouble free design What do you like Date Thu 5 Aug 2010 17 43 55 0500 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 HP spectrum analyzer question The better way and more inexpensive way now days is to pick up an inexpensive SDR kit like the SoftRock They sell them for just that use 455Khz IF You plug the thing into your computer USB port and sound card input and with some free software can get the bandscope functionality think the kits are 40 or 50 and your time to build it and get it up and running It s pretty cool Side benefit it can be used to demodulate SSB RTTY etc Date Thu 05 Aug 2010 22 06 28 0400 From 2002tii lt bmw2002tii nerdshack com g
29. lt rbethman comcast net gt Subject R 390 urm 25 notes and a bit more The Dallas Lankford pdf and two more notes are uploaded to MY site They can be obtained by downloading lt http nome comcast net rbethman urm25notes zip gt This indeed covers the Dallas Lankford Maint Notes Date Tue 6 Mar 2012 13 43 20 0600 From Tisha Hayes lt tisha hayes gmail com gt Subject R 390 Hollow State News Index have a spreadsheet formatted index of the HSN collection by topics Email me if you want the spreadsheet it was written by someone else Reid Wheeler URM 25D references can be found in editions general 21 4 amp 5 31 3 32 8 41 7 oscillator 34 6 repair case history 38 6 rebuilding 39 6 Back in 07 went on a quest to collect as much as could on the HSN editions and have the same collection up to 53 as has been posted on the list also have a rewritten HM edition of issue 29 and another one dedicated to the R 390 HSN R390 pdf At the time was fortunate enough to be able to reach many of the contributors before they went SK Anything have copies of is free for the asking When was collecting the editions that was the stated and implicit desire to make the old editions available Date Tue 6 Mar 2012 13 48 06 0600 test gear page 389 From Tisha Hayes lt tisha hayes gmail com gt Subject Re R 390 AN URM 25D Repair Info More A few months ago Dallas Lankford pulled his Yahoo list back
30. want to build one but just cannot find a suitable regulator Anyone have any ideas on where can find a regulator for this voltage OR a really good transistor Bipolar or FET circuit Date Mon 17 Sep 2007 15 37 14 0600 From DW Holtman lt tubestuff comcast net gt Subject Re R 390 OT 30V regulator Don t forget about the simplest regulator around the good old Zener DigiKey sells a 1 watt 50 volt zener 1N4757ADICT ND for 0 36 in quanties of 1 They are available in voltages from 1 8 to 200 volts They are simple and almost fool proof Date Mon 17 Sep 2007 16 44 51 0500 From Bill Hawkins lt bill iaxs net gt Subject RE R 390 OT 30V regulator There s a lot of talk about voltage but not about current Both are required to pick a regulator I ve used a Triplett 630 NA for as long as could afford a good meter value its portability and would not think of tying it to a line cord test gear page 161 The 30 volt source draws microamps easily done with a zener diode That s what the zero ohms adjustment is for You can t do insulation resistance without it You can build a DC DC converter for 1 5 to 30 volts at low current with a few parts But how are you going to turn off the 30 volt multivibrator when it s not needed The 1 5 volt source is another matter It draws hundreds of milliamps on the X1 scale Really does seem easier to change batteries than to remove the instrument s portability Test lead r
31. 0 2 00E 06 0 0100000 0 028 10 000 33 0 5 00E 07 0 0050000 0 014 5 000 41 0 8 00E 08 0 0020000 0 006 2 000 47 0 2 00E 08 0 0010000 0 003 1 000 67 0 2 00E 10 0 0001000 0 000 100 87 0 2 00E 12 0 0000100 0 000 10 107 2 00E 14 0 0000010 0 000 1 127 2 00E 16 0 0000001 0 000 0 1 Date Fri 20 Aug 2004 11 27 49 0400 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 RE Mechanical filter repair lt snip gt A short piece of 1 inch copper tube two end caps and a couple of BNC connectors make a fine substitute for those often missing URM 25 accessories the 50 ohm load standard antenna impedance converter and voltage divider Clever workers will mount a Twinax connector on one end and incorporate the needed grounding of one twinax terminal proper loading of the generator and the advisable 10 1 or 100 1 voltage divider all in one unit Date Sat 8 Jan 2005 22 19 07 0500 From lt pdulaff earthlink net gt Subject R 390 Servicing Advice on Signal Generator URM 25D Blank L117 has failed on my signal generator The choke shorted to ground and also took out the 6X4 power supply rectifier While am waiting for the parts to test gear page 345 arrive to complete this fix what else in the unit should change as a preventative maintenance item Date Sun 09 Jan 2005 10 22 45 0500 From Bob Camp lt ham cq nu gt Subject Re R 390 Servicing Advice on Signal Generator URM 25D The basic experience on an R390
32. 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP And Other Signal Generators gt Nobody knew how to build Wien bridge oscillators and RF signal generators like HP test gear page 240 No but good as they were they had their own problems The 200 CD suffers from ground loop and leakage hum that is not horrible but is 20 30 dB above what it ought to have been The solid state ones were way noisier than they should have been gt General Radio stuff was big and heavy and black and was in a lot gt of labs but was nowhere near the high bar that the HP stuff set gt for equipment usable in field service My 805 C and 1606 A got hauled to innumerable transmitter sites over the years as did many many others don t think HP even had an RF bridge until after it bought Boonton in 1959 and acquired the 250 A which was less suited to field use than the GRs Date Fri 14 Jan 2011 13 35 28 0500 From rbethman lt rbethman comcast net gt Subject R 390 Signal Generators et al hope we have come to the end of the big HP stream do have an HP 606B and an HP 410B However for signal generation to align my R 390A and SP 600 use the tried and proven AN URM 25 a TS 505D U VTVM and a TS 585 connected to the audio output It worked for decades and I m NOT about to spend a bunch of to change over believe that Roger AI4NI will say that this line up is more than adequate and up to the task
33. 0700 PDT From Rodney Bunt lt rodney_bunt yahoo com gt Subject R 390 Capacitor Checkers useage The in circuit tester uses the same principle as the Heath C 1 tester For checking shorts they try and get 60Hz signal from the mains transformar to travel through the capacitor for small caps this won t happen so there will be no indication for a short there will be a big signal passing through Then the other test is the open circuit test For this test a high frequency signal is impressed across the capacitor if the cap is open circuit there will be no signal passing through if it is ok then the high frequency signal will pass normaly and give an apropriate indication A fuzzy edge indication on the display shows leakage or intermittent behaviour From Scott Barry Clyde B lt cbscott ingr com gt To R390 E mail lt R 390 mailman qth net gt Date Mon 16 Sep 2002 13 47 37 0500 Subject R 390 Replacement caps for HP200CD The HP200CD have has two Black Cat caps I m going to replace They are 0 5ufd 400VDC know the standard today is 0 47ufd but would be better off sticking to the original value by using two 1ufd in series If do is it acceptable to use 200VDC caps Is there any adverse effect from doing this know that caps in parallel add to the total capacitance but each cap in this case will tend to act independently at different frequencies don t think this is the case with series
34. 10 ohm to 400 ohms of resistance and 50 to 1000 pf of capacitance which was to be tuned out with the antenna trimmer haven t seen any measurements it would be interesting if someone can run some would propose that sensitivity measurements be made using the balanced input assuming 125 ohms impedance test gear page 296 Although the test procedure in the spec calls for a 125 ohm resistor in series with the generator and radio think Nolan s setup is correct because it provides the 50 ohm load for the URM25 generator and a 100 ohm load for the radio The spec also calls for the unbalanced input to be fed through a 50 pf capacitor implying a reactive input impedance Date Thu 20 Jan 2000 11 46 35 0500 From Mark Mohrmann lt mohrmannm mail lsc vsc edu gt Subject R 390 AN URM 25 Capacitor Replacement The R 390A EAC 386 restoration project has been temporarily put on the back burner while attempt to fix a bad step attenuator in my AN URM 25D As long as I ve got the signal generator apart I m planning on replacing the capacitors suggested by Dallas Lankford From what can gather just by his notes without yet opening everything up he suggests replacing C159 162 163 165 166 167 Audio Subchassis C130 Buffer Amplifier Subchassis C155 Calibration Oscillator Subchassis If anyone can suggest other weak spots elsewhere in the rig that need to be replaced I d appreciate hearing from you Otherwise I ll ship this order
35. 141 series if often reasonably priced think you should also consider units made by Tektronix They have the 491 and 492 stand alone units They also have a 7L12 plug in for the 7000 series of scopes The 7000 series are even bigger BA s than the R390 but are built extremely well and are cheap cheap cheap got a 7904 500MHz mainframe with four good working plug ins for 200 Although the 7L12 plug in hovers in the 500 range Two more points My observation is that on epay a particular type test equipment seems to come in spurts and prices vary wildly Secondly take a long hard look at what you want to do It is easy to get lots of money invested on an obscure idea That s how got seven HP 3568B selective level volt meters Three work OK two need small repairs and two are only good for parts but were supposed to be working got them for less that the dealers wanted but ended up spending close to 1K over a two year period But in reality will only end up using two or three at the most It is very easy to get carried away on the minor stuff Date Sat 14 Aug 2010 22 04 52 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP Spectrum Analyzer test gear page 227 One shouldn t have to pay 1000 for a 3585A although as Perry noted asking prices vary wildly One thing to think about carefully when buying a SA is the minimum IF bandwidth A lot of analyzers don t have the narrow bandwidth IFs you need to clearly
36. 19 28 0400 From K2CBY aol com Subject R 390 URM 90 LCR bridge question OT I ve used a URM 90 for a number of years and have found it to be highly accurate effective and pretty straightforward to use The built in 1000 Hz generator is adequate for most all purposes The URM 90 is not really great for extra low values of inductance and capacitance lt 10UH lt 100pF but it s adequate For RF scale values you re better off with a grid dip meter or a Q Meter if you want to get really fancy Where the URM 90 really excels is making up or picking precision value capacitors from say 1000pF to 0 1uF to make up audio filters phase shift networks or timing circuits It also works well in sorting through junk box inductances expecially chokes and iron core audio frequency stuff A more generally desirable instrument might be the ZM 11 U R C L bridge It has only about half the accuracy of a URM 90 but it allows you to make leakage measurements at voltages up to 500 and also permits you to measure the value of an electrolytic capacitor with a DC voltage impressed on it It s probably more useful than the URM 90 in determining the GOOD BAD state of a capacitor It also seems a little easier to use than the URM 90 takes less time to find the balance point Like the URM 90 the ZM 11 uses an internal 1000Hz oscillator as the signal source The main difference apart from precision is that the URM 90 permits the DC measurement of resistors w
37. 20 07 0400 Subject R 390 URM 25D recap picked up a URM 25D at Dayton this year This unit had the typical loss of modulation described in many of the messages posted in the archives Upon inspection ALL the large paper caps located on the modulation board were physcially wet with a slick discharge from the innards of the caps So obtained replacements and installed new caps as recommended in the archives even broke open the case and replaced all the similar paper caps located on the various internal modules which were also wet with a discharge Upon reassembly all functions work as intended and after a few hours warm up the stability of the unit is rock solid Now on to my question in the list s experience is a recalibration necessary after recapping this unit The frequency alignment seems to be quite good But am uncertain about the calibration of the voltmeter function have the Navy manual for the URM 25D but am interested in tips on calibrating the voltmeter function For instance 2 0 volts are mentioned as an approximate value at the RF output jack Is a RF voltmeter required for this measurement Is this voltage a DC voltage Any help here Thanks for your past support Jim From JM CO lt jmerritt2 capecod net gt Subject Re R 390 URM 25D recap Date Mon 24 Jun 2002 14 15 30 0400 test gear page 337 Yes an RF voltmeter is required here The signal IS alternating current not DC All AC voltmeters ha
38. 276 gt beast and do it to it gt gt You mean to replace the capacitors It s well worth doing About 5 gt dollars of capacitors will eliminate a major chunk of the potential gt problems with the thing Dallas mentions that the Vitamin Q types do not normally require replacing Why not since they are also paper Do they go bad in the 390xx Another comment he made in the cover letter was to change the AC power filter chokes with Miller 4622 s the originals were underated and overheated splattering red gook inside the filter case gt gt gt Someone forgot who sorry also mentioned going to TNC to gt improve the shielding integrity gt gt With good coax the BNC s are fine since you re only hitting a max gt of about 51 MHz only use mine to about 10MHz anyway Tried it once on 6M but drift was way too much Use a HP 608C above 10 Mhz Also have a GR 1025A Sweeper Generator which is a real fancy piece of gear really appreciate the low phase noise from these BA s as compared to several of the early synthesized gear They work just fine with my regular station rice box Kenwoods etc and various VHF UHF xvtrs Some day may break down and get a HP 8640B Date Fri 07 Jan 2000 21 25 24 0500 From Randall C Stout lt rcs1 sprintmail com gt Subject R 390 HP 8640B questions A couple more signal generator questions The HP 8640B is listed as going down to 0 5MHZ but is there enough overlap to
39. 3 volt filament transformer and an octal socket for one of the plug in ovens and a conventional crystal socket for the room temperature crystals suppose that could do it with just the oven socket and either switching off the filament transformer or just not plugging it in the wall for the ones that don t normally run in an oven could mount a couple of BNC connectors for the signal generator and scope connections Looking at the specs for the different crystals used by the R390A I see that some of them use a shunt capacitor of say 5 or 7 mmf etc Suppose that mount a transistor socket or something similar under the open crystal socket and or under the octal oven socket so that can simply plug in the particular value capacitor that is recommended for whichever crystal that want to test Maybe it would be better to check the circuit that the crystal is used in in the receiver and use the capacitance value of it realize that the frequency can be pulled to a small amount with capacitors but would this be a reliable and accurate method for determining the actual frequency of the crystal down to maybe fractions of a hertz for low frequency crystals and maybe one hertz for the HF ones that I d see in produce in the receiver itself Date Mon 10 Jan 2000 10 39 00 0600 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 Sig gen for checking crystals gt Can give you my way to do it if you have
40. 35 0500 test gear page 308 From Jim Brannigan lt jbrannig optonline net gt Subject Re R 390 URM 25 Stability To state it a different way the drift is 100hz per minute or almost 2hz a second That would be annoying while trying to align a selective circuit My 25D is stable enough at low frequencies to align an IF without retuning the 25D At progressively higher frequencies it is less stable but the circuits are broader so it is nota problem At 6M or tripling to 2M the 25D is all over the place but still usable Nolan I ve checked the voltmeter on the 25D against a hopefully calibrated scope and it was in the ballpark Any other information would be appreciated Actually any tips for calibrating test equipment would be helpful Those of us without access to laboratory standards are always wondering if our test equipment is giving us good information Date Thu 14 Dec 2000 09 31 37 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 URM 25 Stability WELL if it drops 2 kc when running at 30 megacycles that is wonderful If it drops 2 KC when running at 50kc that is terrible Date Thu 14 Dec 2000 08 13 46 0600 From J G Kincade lt w5kp swbell net gt Subject R 390 Do it yourself TE Calibration Keep an eye out for small calibrators at surplus dealers Being oddball equipment they tend to go cheap in spite of their very high price new got lucky and bought a small TEK Calib
41. 4 AC cord amp lead storage None Yes 5 Gasket around cover None Yes 6 Socket Saver adapters None Provided According to the TM 11 6625 274 35 field and depot maintenance manual the TV 7D U also has antiparasitic beads placed on leads soldered to all tube sockets except sub miniature sockets X109 and X110 pins 1 and 4 of X103 4 pin and X105 6 pin and pin 8 of X111 octal There are several circuit changes noted in a table but won t go into them as they relate to the schematic Michael and each bought NOS TV 7D U s in their sealed Signal Corps boxes a couple or three years ago at the Gaithersburg hamfest If this is what he s offering for sale it s probably in like new condition like mine still is No mine is NOT for sale lt g gt However I m sure you can get a well used one for less but if you what want the best I m confident that it s worth at least what he s asking I m sure he ll that and more if he puts it on eBay Date Wed 10 May 2000 11 35 54 0500 From Nolan Lee lt nlee gs verio net gt Subject R 390 mil tube tester info update I ve typed in well over a thousand lines of settings data so far for the TV 7 series tube tester from the January 1962 edition of the TB 11 6625 274 12 1 settings test gear page 257 book I m using the edition with Changes up thru number 3 incorporated After finish typing in all of the data from this book I ll start adding all of the Air Force 32 changes I ve got almos
42. Bill Smith lt billsmith ispwest com gt Subject Re R 390 Meter Meister test gear page 90 Date Mon 16 Jun 2003 00 09 22 0700 Thank you for the compliment Gene don t have any specific tool just grab what is handy It might be a toothpick non magnetic or a pair of stainless steel tweasers picked up somewhere Also use a small tip screwdriver If real trouble is found with the spring it can be usefull to temporarily unsolder it from the small mount that normally protrudes from the meter bridge The spring can be reformed and then positioned so that there is minimum deformation when it is resoldered to the post Date Mon 16 Jun 2003 09 16 46 0700 PDT From lt jlap1939 yahoo com gt Subject R 390 Meters and things Enjoy the material on damage and dirt in meters It is an interesting thread that has a number of applications Thanks to those who sent private responses about r 390 SSB They were appreciated Date Mon 16 Jun 2003 16 25 03 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 Meter Meister Nope no ranges no resistors except the two coils on the back panel One wire goes directly from the terminal on the side of the box to one end of the coil the other wire goes from the other terminal to the two resistor coils in series then to the other end of the coil Simple very simple just doesn t work much Reverse needle movement doesn t peg only about the same as fo
43. Date Mon 25 Nov 2002 13 16 51 0800 From Dan Merz lt djmerz 3 cities com gt Subject Re R 390 xtal wave spikes Bob the wave amplitude ranges from about 1 to 1 7 volts pp output from the cathode follower that feeds to the single balanced diode ring detector with a couple of the xtals producing 0 8 volts pp don t think there is gross distortion other than what described but I m just looking at it with a scope I ll order the dead crystals after trying a couple of different tubes in the oscillator but don t expect a miracle at this point with tube substitution Your comments about the square wave brought back some faint memories of fourier series representation of square waves but my memory bank need refreshing about that and what a mixer really does besides adding and subtracting the frequencies of waves put into it do remember that a square wave is generously endowed with waves of many frequencies and hence its utility in testing thanks for the comments From Bob Tetrault lt r tetrault attbi com gt Subject RE R 390 xtal wave spikes Date Tue 26 Nov 2002 08 48 40 0800 Dan The more amplitude the better subject to the limitations of maximum diode current at the higher amplitudes It does concern me that your minimal amplitude approaches the turn on voltage of a silicon diode those bands will be more likely to perform poorly in the presence of strong signals as well as suffering from increased conversion loss OT
44. Dec 2003 10 21 49 0800 PST From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 URM 25D Signal Generator Speaking of signal generators how does the URM 25J stack up against the others mentioned Is it substantially better than the D model Just what are the differences Date Mon 08 Dec 2003 11 05 53 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 URM 25D Signal Generator gt Speaking of signal generators how does the URM 25J test gear page 343 My guess is about the same gt Is it substantially better than the D model Just what are the differences Can t tell you but my notes on the URM 25 include the following messages assume that more attenuation stages means an additional step in the output attenuator do not have pictures with enough clarity to see if this is true or not Date Tue 6 Jul 2004 13 46 17 0700 From Jack Antonio lt scr287 sbcglobal net gt Subject Re R 390 URM 25 RF output measurement lt snip gt Also I ve owned two URM 25s a D model and F model The output attenuator in each is basically a bunch of resistors in a super fancy rotary switch arrangement the last resistor being a precision resistor in the neigborhood of 50 ohms 49 9 50 1 can t remember exactly In both of my URM 25s this resistor was burned open Then to add insult to injury back when Fair was selling the URM 25 output attenuators ordered one an
45. G probe The instrument has full scale ranges of 1mV to 3 Volts full scale in 8 ranges It should be able to be read down to about 0 2mV or less One interesting point The screw on probe tip is missing test gear page 69 though believe the probe is electrically complete But on the 1mV range the instrument is very sensitive even shining a FLASHLIGHT or other light on the end of the probe affects the meter ZERO Discovered when turned the bench light on QUESTIONS Anybody know the frequency range input impedance etc of this unit Can this unit be used IN PLACE OF the HP Voltmeter RF probe in the alignment of R 390A s etc From Bob Camp lt ham cq nu gt Subject Re R 390 Millivac RF Voltmeter help Date Fri 30 Aug 2002 20 35 22 0400 Later on these guys got bought out by Boonton The Boonton RF millivolt meters are direct descendants of the unit you have The circuits in all of them are fairly similar do not have data on the exact unit you have but here s my guess Frequency range to 1 GHz Input impedance gt 5 K ohms less than a pf or so The screw on tips should be easy to find since have only seen one type The hard part is getting a unit with the probe still on it They matched the probes to the instruments so a late model probe probably will not work right with an early model instrument The light sensitivity is due to your hitting one of the two diodes in the head with light They do a difference measure
46. HP 410C when the probe got with it in a recent buy turned out to be bad The HP probes can t be fully disassembled for example you can t replace the coax if the center test gear page 52 conductor breaks at the probe end have a couple or the USM 116 a and b think that don t use anymore as have gotten an HP 410B and 410C online now for boatanchor work The USM 116 s came with a spare probe which is how got the one to adapt to my 410C Date Wed 18 Apr 2001 09 30 05 0500 From Scott Barry Clyde B lt cbscott ingr com gt Subject R 390 HP410B question Is the HP410B an RMS reading meter When placed in parallel with my Fluke RMS reading meter the two meters don t show the same value think the Fluke is correct as was seeing approximately 10V p p on the scope and the Fluke was showing around 3 8V but the HP was showing only about 2 8V Is the HP just out of calibration Date Wed 18 Apr 2001 11 24 51 0500 From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 HP410B question An audio sinewave Not sure of the frequency but think it s 600cps Date Wed 18 Apr 2001 11 37 20 0500 From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 HP410B question That s what had done The signal in question was an audio sine wave looked to be a good sine wave on the scope The two meters did not read the same value suspect the HP is out of calibration but wasn t sure
47. HP 8640 gears received from Italy bought them on the e pond for spares should the 8640 ever need them The trusty URM 25D could also be warmed up to provide signal for the 390 or 390A in case of an 8640 failure suppose bult http i180 photobucket com albums x257 fish1_07 gears1 jpg http i180 photobucket com albums x257 fish1_07 gears2 jpg http i180 photobucket com albums x257 fish1_07 gears3 jpg http www youtube com watch v MszkI32MFPE Date Wed 23 Feb 2011 21 17 43 0500 From Jerry O Stern lt jsternmd att net gt Subject Re R 390 R 390A tube adapter Lots of tube adapters on Ebay with 7 octal and 9 pin and with tube pin test points as well best quality bakelite made by vector and pomona Be careful to get the skinny versions as the standard 7 and 9 pin are too fat to fit inside a tube base with integral shield sleeve Date Fri 4 Mar 2011 22 33 09 0500 From Steve Byan lt stevebyan verizon net gt Subject Re R 390 OT HP 410B Tubes Thanks for the report on your HP 410B experiences It s motivated me to get mine off the shelf and on to the bench One question how the heck did you get in there to recap it I ve removed the chassis screws and desoldered the AC line input connection to the front panel switch but the cable harness is still to tight to let me into the innards Did you have to unsolder much of the wiring Mine s an old one too pre PC board did test gear page 246 manage
48. I ve used a 608 for higher freqs How does the HP 606 compare to the URM 25D At the very least it seems to be heavier Date Tue 18 Jan 2005 01 39 05 0800 From ELDIM lt eldim att net gt Subject Re R 390 HP 606 vs URM 25 The HP 606A is definitely a step up from the vintage AN URM 25 series Signal Generators However the URM 25 Series did have a feature that admired and appreciated which was the external X200 microvolts that was sure handy to keep a Freq Meter connected to The 25 covered 10 KHz to 50 MHz in eight ranges whereas the 606A covers 50 KHz to 65 MHz in six ranges The 25 is smaller lighter and takes up much less bench space but that is where it ends test gear page 349 The 606A has much better accuracy of 1 plus 100 Khz amp 1 MHz internal Calibrator The 606B was another step up but required the HP 8708A Synchronizer that provided PLL plus some more amenities Of course you can use it without the synchronizer and essentially you still have a 606A The 606A sold for 1350 back in 1963 have used both in the Air Force from 61 but the 25 was replaced by the 606A somewhere along the line Wealso had a HP 608 Series which covered 10 MHz up to 400 Mhz depending on the model This was also a very nice generator for its time and its earlier military counterpart from the AN URM 26 series In any event either generator is very capable of aligning radios receivers from the bygone era You re sure to fal
49. It could have been the 78xx family with the 79xx being a gigahertz mainframe The Atomic Energy Commission bought a lot of the storage scopes planted them down in a hole with a big A bomb and captured signature events from the explosion Then with a video camera they transmitted this visual outside where it was captured on some form of scan converter The scope and the video camera would become vapor in the explosion but the event was captured by the scope and camera for analysis The scope had to work perfectly just one time in its career The AEC kept coming back for more so it must have done its job Tek knew how to make scopes better than anyone but they couldn t quite get the spectrum analyzers the way HP did and in that era Tek was unaware of the need for digital instruments like logic analyzers HP really bowled them over with a new class of instruments as the digital era came into being Date Mon 29 May 2000 15 04 02 0500 From Dr Gerald N Johnson lt geraldj ames net gt Subject Re R 390 probes liked the 465 for looking at single trace events It had screen intensity to see 100 ns cm events in full room light The 475 with its different CRT doesn t do that as well The 475 may be unique in portables with a 2mv cm range The 475A sacrificed that range for 250 MHz bandwidth 465 100 MHz 475 200 MHz 475A 250 Mhz 485 350 MHz The HP 1740 was the equal in performance to the 465 and many potential buyers list
50. Mini Circuits gt in line attenuators placed right at the input of the DUT rather gt than using the internal attenuator in the sig gen By right at gt mean connected using just a coax adapter no cable at all prop the gt attenuator up on a stack of books or something so it isn t just gt hanging there That way the level in the connecting cable is much gt higher and any QRM QRN introduced before the input jack of the DUT is gt attenuated by many dB Ideally you would move all of the gt attenuation to the DUT end of the cable and run the sig gen at 0 dBm gt or more If nothing else get three or four Mini Circuits HAT 30 gt fixed attenuators http www mini circuits com pdfs HAT 30 pdf gt 10 each and put them right at the input of the DUT to do 30 60 gt 90 or 120 dB of your attenuation there and do the rest always less gt than 30 dB at the sig gen gt gt Preventing leakage into the DUT other than through the antenna jack gt can be harder and of course to the extent that you reduce it your gt results will not represent how an off the shelf unit works A GOOD gt power line filter is mandatory on both the DUT and the sig gen Use gt copper mesh gaskets at all cabinet joints or these days conductive gt polymer shield gaskets One of the greatest sources of this ingress gt or egress in the case of signal generators is the chassis openings gt for controls One thing th
51. N Frederick Ave Suite 11 W Gaithersburg MD 20877 USA Tech Support 301 840 5477 Orders 800 783 2666 24 hour Fax 301 869 3680 email address rfc therfc com Call or send an e mail He knows what you need and has it UPS stops there every day I m a happy customer especially since can drop over there at lunch time He recently sold me a piece of cable marked M17 84 RG 223 Mil C 17 Times Microwave Systems 68999 AA 3413 It has two layers of silver plated braid shield and a solid silver plated center conductor l m going to use it to feed my 30L 1 from the 32S 3 In the oddity category just got three BNC type Tee connector blocks which are triax coax that is they have a three conductors one center and two separate coaxial shields They are marked DAGE 95712 4972 1 The end with the bayonet collar is female in the center and the sleeve ones with the bayonet pins has a center male pin The center and intermediate coax are gold plated No doubt these are for Ghz use and would provide excellent shielding but have neither mating connectors nor cable to make up leads Any info on these much appreciated Dage appears from a web search to be a UK company that got bought up in 1997 One last note if you are measuring very low signal levels and have your counter hooked up to the High output on the URM 25 or similar output on the later HP 606 s you are fooling yourself and your receiver Date Sat 08 Jan 2000 22 19 19 06
52. Now for the problems on my tv 7 u when do the range check b to c the gt meter goes off scale past 120 also on some tubes 6v6 6L6 etc on range C any ideas Get a schematic you won t get anywhere without one don t know the TV 7 specifically but do know the 600A and most of the Hickok designs are closely test gear page 268 related From your description the meter is off cal or more likely the plate supply is out of balance The 600A applies 120Hz pulsating DC to the plate and 120Hz pulsating DC bias to the grid with a little bit of 6 OHz AC superimposed The meter reads the difference between one plate current phase and the other If the circuit s balanced the tube s raw plate current is nulled out and the only thing that shows is the plate current change due to the AC grid signal If you re reading high with tubes that pull a lot of DC plate current the circuit s out of balance My guesses 1 resistors in the range switch 2 the shunt pot and associated 12 ohm or so resistor 3 the 83 or 5Y3 or 4 a bad 83 plate winding in the transformer When you test the 83 or 5Y3 it s very important that the two plates have the same emission By the way if the TV 7 is like the 600A you can pull them out and test them in the same tester the RECT test does not use the rectifiers The Hickok 800A is a 600A with a different nameplate When they made the 8000 there was so much outcry it couldn t test any of the older tube
53. One of the best resources for the older Tek gear is two Yahoo groups TekScopes and TekScopes2 The 547 HV transformer has been pretty much reverse engineered and there is one member the last time was visiting the group was rebuilding them They are all failing due to moisture They are one amazing piece of Tek gear from the BA period Date Sun 5 Aug 2012 21 03 31 0400 From Robert Newberry lt N1XBM amsat org gt Subject R 390 Testing tubes r392 would like to test the tubes in my r392 Can test those tubes in a standard tester Or do need a special tube tester FYI I m relatively new to the vacuum tube world Date Sun 05 Aug 2012 21 34 42 0400 From Glenn Little WB4UIV lt glennmaillist bellsouth net gt Subject Re R 390 Testing tubes r392 Is the R 392 working If so your tubes have been tested by the best tester available the equipment that is using them If the R 392 is not functioning do you have a service manual If not this should be what you get next would then isolate the defective stage s and check the tubes that are possibly causing the problem Any standard tube tested that has setup information for the tubes in question will work A mutual conductance tester would be best Date Mon 6 Aug 2012 09 56 31 0200 From sigmapert lt sigmapert gmx de gt Subject Re R 390 Testing tubes r392 If you re collecting vacuum tube gear in my opinion a tube tester is a must The most authentic tube tester for m
54. Proc txt gt It must be exactly as listed The server is a case sensitive UNIX based server Enjoy am more than happy to share information lt snip gt Date Thu 01 Mar 2012 14 44 28 0500 From rbethman lt rbethman comcast net gt Subject R 390 AN URM 25 Manual To get the schematics and very detailed manual s go to Edebris You want all the NAVSHIPS manuals Date Thu 1 Mar 2012 13 48 11 0600 test gear page 379 From Mike Andrews lt mikea mikea ath cx gt Subject Re R 390 HP 410Bs and AN URM 25s Let me again plug lt http hamstuff ath cx gt for pictures of ham stuff radios test gear etc The price is right Date Thu 01 Mar 2012 15 05 14 0500 From rbethman lt rbethman comcast net gt Subject R 390 AN URM 25s I ll add that some others along with myself have experienced RF leakage on these Sig Gens am going to apply Scotch 24 I just went and picked up my last boxed roll Old number from back when worked with high voltage production and distribution Shielding tape It is tinned copper wire Braid It comes in a roll 1 wide and 15ft long am either going to enclose the rubber gasket within it OR I ll simply add it as a shield between the front panel and the case This will result in a far better RF shield Take this advice as you decide I ve done this with Radios ever since got licensed in 1980 whenever felt that RF leakage may be an issue Date Thu 01 Mar 2012 15 12 08 0500
55. R 390 TV 7 Shorts Problem Especially SP 600 switches lt grin gt Date Sun 26 Nov 2000 20 57 26 0500 From Barry Hauser lt barry hausernet com gt Subject Re R 390 TV 7 Shorts Problem Thanks for the tip the switch seems like a possibility Hey you wouldn t be suggesting that there are some conductive uh chads in there Oh no It s bad enough that we have to do so much switch flipping with these testers now there are gonna be a half dozen recounts per toob Seriously though don t know how you d avoid beating up that function switch The procedure is to run it through all 5 shorts positions before going on to the quality test As understand it you re not supposed to do a quality test on a tube that shows a short lest you damage the tester Are you saying that you skip the shorts test I ll check out that switch have compressed air cans and plenty of deoxit also suspect the 7 and 9 pin sockets which are very close together The socket saver in the 7 pin is a little loose Date Sun 26 Nov 2000 20 47 29 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 TV 7 Shorts Problem Ceramic wafers are sponge too They are not glazed Date Tue 28 Nov 2000 01 39 23 0500 From Barry Hauser lt barry hausernet com gt test gear page 260 Subject Re R 390 TV 7 Shorts Problem opened up the tester and scouted around did notice some micro metal fla
56. R 390 Tags on urm 25d thought the URM 25J was a URM 25D with a different accessory or two At least that was what read on one of these lists awhile back Date Wed 7 Nov 2001 08 32 29 0800 From Roger L Ruszkowski lt rlruszkowski west raytheon com gt Subject Re R 390 Tags on urm 25d It s a D test gear page 327 The tag is attached to the front panel The front panel is attached to the guts The is what makes the model The case is just there to keep the dust out Ok so some one droped a D model into a J case Ah the wonders of interchangeable parts The J version is the 9th or 10th version Date Wed 7 Nov 2001 14 49 40 EST From Llgpt aol com Subject Re R 390 Tags on urm 25d Date Wed 19 Dec 2001 21 01 39 0000 From Phil Atchley lt ko6bb elite net gt Subject R 390 URM 25D info have a URM 25D here with all acc in the lid that think may need some tlc It does work and generates a carrier seems remarkably accurate in frequency where I ve tested it BUT it appears to have no 400 or 1kKHz modulation Any common failure modes that should look for first downloaded the manual for the URM 25F from the BAMA site but haven t looked at it yet How does the 25D compare circuit wise and mechanically to the 25F It appears that this would be a very good generator to align my longwave beacon receivers as it goes down to 10kHz Date Wed 19 Dec 2001 17 30 35 0500 From Roy Morgan lt roy
57. The Technician s Handbook that fits inside the case is also included also have two of the neat probe meters that came with the kit However they are missing the metal spring ring that keeps them closed don t know if they work Here s what s missing The decade resistor decade capacitor all the tools the probes soldering iron The TV 4 alone sells for around 200 00 when they surface The metal case with the signal tracer probes and headphone is very hard to find but it appears complete am asking 250 00 for it plus shipping know that could get this and possibly more easily on ePay but I d like to see this rare gem go to one of the R 390 gang If interested please reply by e mail Date Sat 19 Feb 2011 20 30 50 0600 From Randy and Sherry Guttery lt comcents bellsouth net gt Subject Re R 390 HP 410B Question gt have an HP 410B that I m restoring It has a small value cap 5000pf or so gt across the meter but it also has a 50uF cap across the meter as well I ve been gt advised to just remove that 50uF cap as it isn t really needed it s not on some gt of the newer models When asked why two caps he noted that the smaller cap was to bypass any RF that might leak into the meter movement from the front since the shielding wasn t all that good there and the larger one was to slow down the response so the pointer and the rest of the works didn t slam off the stops so hard on an overload He too noted t
58. a number of HP items in my lab You can also find pulled Rubidium clocks with a 10MHz out very cheap now as well under 100 Nothing like knowing you are dead on accurate Keep in mind the 10 MHz external reference is just something wanted to have have a very bad case of gadget itus Hi Hi The 8640B s calibrated are plenty good enough for almost anything you will need for working on HF receivers test gear page 232 His email address is www gcbojr aol com 73 Glenn Scott WA4A0S DSM Labs Date Mon 10 Jan 2011 12 15 14 0800 PST From Mack Rogers lt n4vgb yahoo com gt Subject Re R 390 8640B And here thought myself as being a bit obsessive compulsive when purchased my second 8640 Bottom line is it s the biggest bang for the buck out there at this time It s a very good and accurate sig gen with a super clean output Date Mon 10 Jan 2011 15 35 00 0500 From Doug Massey lt dougmassey masseyradiolabs com gt Subject Re R 390 8640B Date Mon 10 Jan 2011 14 53 47 0600 From Ben Loper lt brloper gmail com gt Subject Re R 390 8640B This may be a tough question to answer but how tight should the tuning knob on an 8640B be know it shouldn t spin like a well adjusted R 390 On mine it s consistent across the range and makes no weird noises but there is definite resistance when turn it and since this is the only one I ve ever had don t know if that s normal assume the know should be fairly
59. a work of art Good time to check and clean the switch contacts My 6BE6 had a crack in it but it still worked Good luck getting the tubes out Date Fri 21 Dec 2001 09 57 00 0500 From Bill Cotter lt bcotter pop uky edu gt Subject R 390 Re URM 25x info Speaking of turrets After going through several 25D s and 25F s I ve noticed that many have broken turret clamps apparently a weakness in the casting I ve been fortunate enough to locate a few intact turrets to replace the broken ones that effected operation And some 25 s don t seem to be effected when changing bands haven t tried it yet but it may be possible to use some of the JB Weld techniques to repair the clamp Given the nature of the clamp to maintain compression I m not sure even JB could stand up for a long time test gear page 332 Date Fri 21 Dec 2001 09 46 35 0600 From blw lt ba williams charter net gt Subject Re R 390 URM 25D info Be sure to ask for R J Lee He is pretty helpful He wrote a note with the shipment apologizing for the banged up case cover The extra knobs and bulbs were nice to get originally called about a checked unit and he explained what they do for the extra money He suggested that replace the caps myself and said he would pick out a very good one to send don t remember the checked price but unchecked was 90 don t remember the values of the replaced caps as the notes refers to red ones and br
60. ah7i atl org gt Subject Re R 390 Advice Proper Use of Meggers Have your boy crank until he develops a fine sheen of sweat If he is dripping he s working too hard and will be useless by days end There is also a risk of sweat drops affecting the local conductance If he is not sweating either he s not cranking enough or it s too cold to be working If the later go sit by the fire and break out some scotch Megger for sale You can e Measure resistance of your ground system e Perform geophysical surveys to find ground water or minerals e Coax worms from the ground for fishing e Extract information from children as to WHY they were not cranking the megger fast enough e Stimulate plants to produce SUPER tomatos Biddle last calibrated 1995 Calibration should hold for at least 100 years 400 seriously would not sell for less as this is a weeks RENT on one pick up Canton GA 30114 From Bernie Nicholson lt vk2abn batemansbay com gt Date Sun 8 Feb 2004 21 36 37 1100 Subject R 390 Meggers test gear page 100 MEGGERS Hi guys have always used a meggar for testing capacitors and high value resistors have been an Electrician since the 1960 s meggars come in various shapes and sizes 500 v is the smallest in Australia because it is normal to test insulation resistance at twice the applied voltage which here is 240v they also use 1000v meggars here to check Insulationt on line voltage circuits which is
61. and 54x series were copied by other military contractors which eventually cost uncle Sam a few million in penalties for theft found that plain 7400 series TTL logic could function on things that wouldn t trigger my 543 though it was good enough for my Phd research on using the power line at about 60 Hz for communications sold it to the dean of the ISU engineering college The 53x main frames had a bandwidth of 20 MHz and the 54x mainframes went almost to 30 MHz though few plug ins were as fast as the mainframe And then the 585 wider band scope with incompatible plug ins And a sampling plug in useful for cable checking These were all well used by 1963 when graduated the first time By 1969 the 56x family of compact scopes with two compact plug ins were around the 564 offered screen memory Sometime after that the 5000 and 7000 series of scopes with many miniature plug ins arrived and they had few tubes other than the CRT and high voltage rectifiers The first truly portable scopes were in the 45x family though the later 465 475 and 485 put them to shame The 465 and HP 1740 came out at the same time with only a couple words different in their specifications They both work very well and either is a good choice for a relatively modern portable dual trace scope for all work up to 100 MHZ spent the money 2100 on a new 475 figuring the 200 MHz speed would fill my needs for a long time and it has I m no fan of digital scop
62. and low emissions weeded out In many tube applications that all you need to do The noise of the tube is not reverent to the circuit performance Or the noise is below a relevant factor in the circuit Then us receiver guys come along with extreme demands for tubes Tube testers just will not tell you the same thing about a tubes noise as plugging a 5749 into the first IF of a R390 amplifying the noise through an IF and Audio test gear page 248 subsection and measuring the output to fractions of a DB While you are doing these type of noise test also thwack them to see if they are microphonic 6C4 will become microphonic in the mixer stages Date Fri 01 Oct 1999 12 25 01 0500 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 Tube testers One test you missed grid emission Back in the tubes in TV set days some repair shops swore by grid emission testers made more good diagnoses with the grid emission tester than the standard tube tester without grid emission Its certain that in a receiver grid emission wrecks AVC action And its worse in receivers where the IF tubes are run at high currents to get the gain after the selectivity such as in the 75S Collins lines Though there its easy to detect When the S meter deflects backwards its time to look for an IF tube with grid emission There used to be a small tube checker made just for testing for grid emission have one but haven t used it much b
63. apologize it came during all the doctor chasing issues This file is composed of six pages that test gear page 400 apply to the URM 25D refurb The first two pages of this document used MS Word 2010 BUT saved it in Word 97 2003 doc format are from the NAVSHIPS 92134 A pdf that is on EDEBRIS and refer to frequency alignment The remaining four pages are notated schematic pages from the above manual and are in fererence to the refurbishment procedure Additionally the 5VDC lamps noted by these folks are Jameco SKU141066 This document is on my site This is NOT a small file It is 34 410KB IOW just a tad over 34MB This is the best can get it down to The individual pages scanned 24MB each This is why inserted them into Word Document Don t ask for it to be zipped already tried this and it saved 210KB Hope this makes more sense for those trying to rework one of these Date Tue 13 Mar 2012 15 49 39 0400 From rbethman lt rbethman comcast net gt Subject R 390 URM 25 info doc AMENDED Thanks to Al Parker He downloaded it and converted to an Adobe pdf file It is now only 6MB in size lt http nome comcast net rbethman urm25 urm25 pdf gt Date Sun 1 Apr 2012 17 08 15 1000 From bernie nicholson lt vk2abn bigpond net au gt Subject R 390 Tek 500 series CRO s Hello John and everyone over the years bought hundreds of 500 series cro s from the Government Auctions here in Australia Back in t
64. are adjustable It s sometimes difficult to spot because just the very tip of the tiny shaft may become warn enough to slip out of center and jam Usually the needle won t move at all but I ve seen cases where they ll move partway in one direction If the meter has adjustable bearings you can loosen a locknut and turn in the bearing slightly to tighten it up If that s the case be careful not to overtighten and make sure the shaft lines up straight as you do so or you ll damage what s left of the pointy end of the shaft or bend it altogether Center the shaft somehow and just tighten a small amount then blow on the needle to see if it swings freely If when it does Stop A bit too much and the needle won t move then back off a smidgen Often these adjusters are secured with a droplet of glyptol or cement Usually a partial situation is obvious because when the shaft is crooked the needle hits the scale but sometimes it s the tail of the needle or some other part that test gear page 88 binds because it rubs up against something or even the spring itself gets out of sorts due to the misalignment Those situations are not so obvious Date Sun 15 Jun 2003 20 26 55 0400 From Gene Beckwith lt jtone sssnet com gt Subject Re R 390 Meter Meister Excellent post and a frustrating subject for the casual meter repairman Agree with ur assessment that sounds like pointer vane is somehow out of alignment but the blowing technique
65. as can be that is a common band for such phenomena if the receiver is compromised for intermod Date Sun 05 Jan 2003 10 42 08 0500 From Bob Camp lt ham cq nu gt Subject Re R 390 kilocycle megacycle movement The FET vom will do fairly well but if you are going to work on old tube stuff you really need a VTVM A lot of the readings are affected by the loading the voltmeter puts on the circuit A ME 26 or it s HP equivalent is a good one to get They are dirt cheap Ebay is a good place to find them The 465 with DVM option is an interesting gizmo have one sitting here Like all digital volt meters it has it s limitations A lot of the alignment procedures are tune for peak or tune for null stuff That s a real pain with a digital display The military version of the 465 should have a manual on the same site as the 390 stuff It s not the same as the one you and have but it might be a help From Dave Faria lt Dave_Faria hotmail com gt Date Mon 3 Feb 2003 12 40 13 0800 Subject R 390 Off Topic Question Good afternoon list need info on a Triplett meter picked up at a hamfest Is there a person or list where can ask questions Date Mon 03 Feb 2003 10 50 59 0800 From shadow lt shadow gilroy com gt Subject Re R 390 Manual Triplett Off Topic Question Dave Triplett has a site Send them a email and include you Smail address If the have a manual or print They will mail you photo c
66. at 2 KC on each of the bands gt How bad is that If it was worse than that what would be the best place to start fixing it test gear page 307 You probably won t unless you start replacing components with better temp characteristics It s more trouble than it s worth It could turn out being one or more of the tubes or even the variable capacitor If you really want to narrow the cause down you might want to compare the drift between both the calibration standard and the RF output and each of the bands and look for common components sections gt several hours before using it should also warm it up for a long time before I ve used tubes 60 years old and never bothered with any kind of break in procedure other than for mercury vapor rectifiers do remember reading that some transmitter tubes should be cooked for a period of time before being placed in use don t remember where read this It might have been the RCA TT 3 or TT 4 manuals But while on the topic of warm up I ve been screwing around with the various models of the URM 25 for a long time If I m going to align a receiver with one always turn the signal generator on the night before with all of the pots fully CCW Ditto for using the HP 606A was looking at the specs on this monster Eaton Ailtech 380K11 that I m playing with and the warm up period for the 10 MHz master oscillator in it is 72 hours Make sure you check the tubes for gas anytime you p
67. attenuator is gt fully seated along it s circumference I d look at possibly adding finger stock or gt copper screening along the perimeter of the front panel where it slips into the gt main cabinet gt gt The step would probably be a pain in the ass but I d verify that gt the cover of the cast housing screws up dead flat against the main gt housing You can verify that the inner walls mate with the cover gt with plastigauge If it isn t then a machinists straightedge would gt let you know if the cover was at fault or the main casting If gt it was the cover a little time spent on a lapping block would gt fix it If the main casting was the problem you have to remove gt whatever components that would prevent it from lying flat on the gt lapping block You should be able to lap it flat without removing gt it s innards Just make it a point to clean the surfaces before gt you flipped it over gt gt read somewhere that copper screen strips placed across a test gear page 320 gt surface to be sealed is better at containing RF than a perfectly gt mated dead flat surface don t know if it s true or not but gt Doc should know If it does indeed work that well if might be gt worth just laying a piece of copper screen over the casting gt before installing the cover Doc I d class that as a conductive gasket I d just almost prefer a knife edge than the gap imposed by the screen wire
68. built up near the top stop So to make a long story short disassembled the potentiometer cleaned it thoroughly with Caig De Oxit and then put a bit of Stabilant 22 on the sliding mechanism I m hoping that all the advice I ve read about De Oxit and Stabilant 22 plus all the marketing hype Caig and the Canadian outfit have put on their web sites are indeed accurate must admit that at least the Canadian company has run some pretty convincing tests showing the efficacy of Stabilant 22 Caig gets lots of good press from the boatanchor crowd but their web site is pure marketing hype Also treated the set microvolts to 10 rheostat the 4 watt rheostat that sets the voltage on the oscillator plate with De Oxit and Stabilant 22 Bottom line on the two pots is that they re much smoother in their electrical operation Particularly the microvolts pot now acts correctly with no non linearity at the top end went through a couple of q tips taking out all the loose carbon Not sure I m enamored of using Mobil 1 on the wiper of a pot if infer correctly that you mean on the actual resistive material thus lubricating the wiper resistive material interface Sounds risky in that ordinary oil to my knowledge isn t known to be a conducting substance Possible but not ordinarily known so We need a organic chemist to chime in at this point Stabilant on the other hand goes through some discussion about being a block polymer I m an EE not an organic c
69. but most all R 390A owners are lucky enough to have B fuses A while back someone was proudly stating that it s his policy to throw out every tube in each of his R 390A s every six months Date Sun 07 Aug 2005 14 18 43 1000 From pete wokoun sr lt pwokoun hotmail com gt Subject Re R 390 tube testers can tell you folks how recall we college co ops did it back at Hickok When the tube manufacturers introduced new tube types 3 5 tubes were normally received along with the new design specs Each of these new tubes was set up on a super lab tester at exactly the published specs to determine precisely how each one compared to the published specs For example one tube might have 104 of the rated Gm while another might have only 97 of the rated Gm believe Hickok s testers usually had a fixed plate voltage but some could be set within limits It was the bias that was adjustable with a front panel control When one of these new tubes was set up in a particular tube tester the bias was adjusted to approximate the plate current that was used in the manufacturers determination of Gm When you had about the right plate curent the shunt control was adjusted so that a tube with 100 of a new tube Gm would read exactly 2 3 full scale on a fail pass type of scale The bias and shunt readings that you set up would be what appeared on the next roll chart If the tester had calibrated Gm scales the bias would be adjusted until the meter
70. buy me a spare just for the parts at those prices Date Sat 29 Nov 2003 15 59 45 0800 PST From John Kolb lt jlkolo cts com gt Subject Re R 390 Signal Generators was Deoxit I ve got a HP 606A I d sell reasonably to someone that would pick it up in the San Diego area Don t want to pack and ship From Don and Diana Cunningham lt wbShak sirinet net gt Subject Re R 390 WTB R390 Knobs Date Sat 29 Nov 2003 18 14 38 0600 James If no one comes forward noticed on the Fair Radio site today that they still show some of the small and medium ones Date Sat 29 Nov 2003 21 37 27 0600 From mikea lt mikea mikea ath cx gt Subject Re R 390 Deoxit The URM 25 I have a D is OK but hands down the 8640B is at the top of my personal best affordable siggen list Mine has Options 1 2 and 3 and it is an absolute mainstay here along with the Tek 465B scope and the Fluke counter Now gotta get some more Good Stuff From JamesMiller lt jmiller1 706 cfl rr com gt Subject Re R 390 Deoxit test gear page 95 Date Sat 29 Nov 2003 22 38 19 0500 have an 8640B with all except the low freq option It doesn t go below 500 Khz now and it would be real nice to have it go down to 455 khz to do IF deck alignments How hard is it to find a low freq option and add it to an 8640B Date Sun 30 Nov 2003 09 12 29 0600 From mikea lt mikea mikea ath cx gt Subject Re R 390 Deoxit oee How hard
71. caps but I m not sure From JM CO lt jmerritt2 capecod net gt Subject Re R 390 Replacement caps for HP200CD Date Mon 16 Sep 2002 15 41 26 0400 Just replace them with 0 47 400V units and be done with it Given the ACTUAL capacitance of the two types new Vs old as well as the standard tolerance test gear page 71 for these types of capacitors which is 20 the chances of either being exactly as marked is practically nil Also there are no circuits in the 200 CD that are that critical as to cap values Leakage as is probable in the old black units is the real culprit that you need to address Chuck NiLNH From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 Replacement caps for HP200CD Date Mon 16 Sep 2002 14 49 51 0500 Actually the caps in there right now were 10 That s what got me to thinking that might need to stick as close to 0 5ufd if possible 0 47 is already at 6 agree that this circuit shouldn t be all that critical but just didn t know if should worry about it or not Sadly the only local place that has parts like this only had one 0 47 400V with leads They had some that were PC mounted but didn t want to try to tack leads on them If could get the board off though could easily mount these to one hole and drill another hole with a jumper Hmmm that might not be all that bad an idea Date Mon 14 Oct 2002 13 35 33 0400 From Michael Crestohl lt mc
72. com e8285a htm was originally trying to buy a 141T that was being offered locally no shipping costs or damage but someone beat me to it So the E8285A was plan B The unit is calibrated and all tuned up ready to go so no complaints subsequently joined the Yahoo hp_agilent_equipment group for old equipment after looking around my shack and realizing that there are about equal amounts of old HP and old Collins gear What is it about Collins R 390A amp R 390 s that goes so well with vintage HP equipment They all seem to go together somehow Date Sun 9 Jan 2011 15 20 27 0500 From Barry lt n4buq knology net gt Subject R 390 HP 8640B vs HP 8654A 8655A 11710B test gear page 228 Anyone on the list have any experience with an HP8654A 8655A 11710B combination The reason ask is have an 8654A 8655A and am thinking of getting the 11710B to get the lower parts of the HF range and was wondering if I d be better off with this or getting an 8640B The combo will give me a greater low end down to 10kc and the footprint is a bit smaller but wondering if there are any other dis advantages Basically l m tired of lugging the 606A up to the bench Date Sun 09 Jan 2011 15 55 44 0500 From Al Parker lt anchor ec rr com gt Subject Re R 390 HP 8640B vs HP 8654A 8655A 11710B I ve had that setup for 4 5 yrs set up amp available in my upstairs shack shop I m afraid haven t used it as much as I d like have
73. could fail and put you into tennis shoe backup mode The same goes for if the gauge reads empty It could be wrong and you actually have a half a tank But maybe not Date Mon 24 Jan 2000 14 20 51 0800 From Glen Galati lt eldim worldnet att net gt Subject R 390 Re TV7 Series Tube Testers TV 7 Series Hands Down Simple to use compact can improvise to check unlisted tubes Jacks for Noise Test B amp k 747 for newer tubes i e Novars Compactrons Won t do Old large base 4 5 6 amp 7 Pin Tubes I ve used my TV 7B regularly since 1969 without any major problems Changed out 9 Pin socket and replaced 83 once in all those years For detailed analysis the TV 2 is very handy but cumbersome and takes much more time to set up The TV 3 and TV 10 are okay although haven t had the experience to evaluate their performance Date Mon 24 Jan 2000 20 47 34 0600 From Randy Guttery lt comcents mississippi net gt Subject Re R 390 OA2 s One other thing might mention kicking the filament up a notch or two if you re REAL brave for an hour or so is a way to boil off the cathode s of indirectly test gear page 252 heated tubes most modern ones This can contribute some to the rehabilitation of a weak performer Date Tue 25 Jan 2000 10 09 33 0600 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 tube testers amp meters EVERY meter should be supplied with back t
74. d agree with this if the R 390 was the only tube type gear you had and you also had a pile of NOS tubes Otherwise find a tube tester indispensibe both for screening and troubleshooting like the military tube testers such as the TV 2 TV 7 and TV 10 The Hickock 539 is also well thought of The cost of these units is outrageous in the current market The Heathkit TT 1 is also good if for no other reason that it tests compactrons and is lower priced My TV 2C is highly prized test gear page 410 Honestly there is no need for a tube tester unless you have a pile of used tubes you are going to sell and want to be able to say they test good The circuit the tubes are used in is always the best tube tester money can buy If you get some tube extenders with test points you can measure all of the tube voltages from the tube side of the chassis Date Tue 17 Sep 2013 12 50 52 0400 From KR4HV lt kr4hv numail org gt Subject Re R 390 Tube Testers FWIW during the early 1970 s part of my long association with and when worked for Motorola in their two way radio division we still maintained a LOT of tube sets never went in a Motorola shop and saw a tube tester New tubes were always put in the radio under test and test set meter readings signal generator settings and other parameters observed to determine if a tube was operating to spec Never ever was a tube tester used or even present in the maintenance shops When new
75. damaged the rectifier Mine checks a little over 2 ohms regardless of the setting of the variable resistor Looks like probably do have a damaged EA53 checked the rest of the wiring and some of the test point voltages and nothing was particularly too badly awry Looks like I m back to looking for an EA53 test gear page 137 Date Sun 26 Mar 2006 21 46 48 0600 From Barry lt n4buq knology net gt Subject Re R 390 HP410B rectifier tubes Oops Make that 300mA heater current not 500uA was looking at the wrong part of the specification Date Sun 26 Mar 2006 23 47 34 0500 From wabate lt wabate verizon net gt Subject Re R 390 HP410B rectifier tubes You sure you don t want a 2 O1C That s what have in my 410B You can use the EA53 but it requires a different plate contact and attaching spring Also the filament voltage is different Don t know if HP made a design change or if they just allowed for a different repair part have an NOS HP replacement part 2 O1C Let me know if you are interested Date Mon 27 Mar 2006 00 09 14 0500 From Drew Papanek lt drewmaster813 hotmail com gt Subject R 390 re 177 question OT gt Hi the substitute for 83 type tube described by The information have read on this modification states that the tester s calibration would be affected and would need readjustment IIRC the calibration standard is a selected 6L6 supplied by Hickok Date 27
76. deck that I d even consider using NOS caps like that in would be the audio deck It s about the easiest to remove As much trouble as it is to remove the RF deck only new over rated OD s are used there It s not worth trying to save a dollar and a half and having to pull the deck down the line somewhere Ditto for the caps in the IF decks on account of the amount of effort it takes to replace them in the first place Finding any NOS Vitamin Q s any more is tough as hell It seems that the golden eared audio crowd has discovered them saw some listed a while back at over three bucks apiece for 30 year old NOS ones No thanks can buy 6 times as many new orange drops for that They sound good Hell can t carry a tune in a slop bucket could care less how capacitors or rectifier tubes sound lt grin gt gt Another comment he made in the cover letter was to change the AC power gt filter chokes with Miller 4622 s the originals were underated and gt overheated splattering red gook inside the filter case Mine had already been relocated and replaced with updated parts There was no evidence that the original ones had failed Relocating them is a good idea My URM 25D model has matching SN plates on the case front panel PS module etc Upon close examination the big orange plate on the top of the cabinet showed that it was a URM 25G that had been over stamped as a D model test gear page 283 One good thing about the G model is
77. do not get hung up on the accessories in the lid being missing If you have a manual you will discover that most of them are just a resistor or a resistor and a capacitor and could easily be homebrewed for a few dollars each This is a good unit in whatever flavor I d suggest you look test gear page 272 around for Dallas Lankford s notes on restoring one if you get one that is not up to par Date Mon 11 Oct 1999 19 10 19 0500 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 URM 25 E and URM 25 F Where might one find Dallas Lankford s notes on the URM 25 I ve not found them on the internet anywhere Date Mon 11 Oct 1999 21 49 32 0400 EDT From Norman Ryan lt nryan duke edu gt Subject Re R 390 URM 25 E and URM 25 F Dallas URM 25 notes are in the Hollow State Newsletter If I m not mistaken all the back issues are still available at a very reasonable cost Lots of good articles on the R 390 as well Contact Ralph Sanserino P O Box 1831 Perris CA 92572 1831 Date Tue 12 Oct 1999 07 07 57 0500 From Jerry G Kincade lt w5kp swbell net gt Subject Re R 390 URM 25 E and URM 25 F Second that motion bought the complete back issue set of Hollow State Newsletter and its the best few bucks ever spent Date Wed 22 Dec 1999 14 38 08 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 AN URM 25D capacitors No fancy equipment needed at al
78. emission One other good test with the emission test is to drop the heater voltage and see how much reserve there is to the emission I ve not refined that test since figure if it has emission at rated voltage and l m running it normally it will test gear page 249 continue to work as long as it works Then it will fail and it will eventually fail they all do Socket savers have always been a good idea Date Wed 03 Nov 1999 21 38 47 0600 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 I F module gt Is there any relationship between a tube with grid emission and one going microphonic I ve never made such a connection Generally I d figure a microphonic tube had cracked grid wire to grid support rod welds from thermal cycling or impact Though since grid emission especially in an AGC controlled stage would drive the grid positive from the emission current through the megohms of resistor in the typical AGC circuit and that would cause the plate current to be high which means the tube gain is high and so a little grid wire motion would be heard at the output more So there might be a correlation Grid emission comes from cathode material having been sputtered from the cathode onto the grid wires which might also make the grid wire heavier and so more subject to motion from external sonic excitation e g it acts microphonic when tapped Without confirmation of the grid emission by a po
79. eshop1 chem buffalo edu test bench equip html Date Tue 22 Mar 2005 06 44 52 0600 From Dave Merrill lt r390a rcn com gt Subject R 390 Re TS 505 Manual On Line LOGSA has TM 11 5511 for the plain TS 505 U without suffix https www logsa army mil etms find_etm cfm Date Tue 22 Mar 2005 08 26 55 0600 From Barry lt n4buq aol com gt Subject Re R 390 TS352 Meter If these are standard pin jacks and tips Mouser sells them You might not be able to have the 4 40 threaded tips but would think you could use a standard probe tip and use a pin plug on the other end Date Tue 22 Mar 2005 10 56 08 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 TS 505 Manual have them in PDF form and see got them from the LOGSA site https www logsa army mil Scroll down to manuals online or go direct to https www logsa army mil etms online htm then Accept then enter the site search in the title field for TS 505 You ll find the three manuals PIN TM EM Number Current Change Publication Title partial test gear page 118 lt https www logsa army mil etms data A 018850 pdf CFID 3052807 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt 018850 lt https www logsa army mil etms data A 018850 pdf CFID 3052807 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt TM 11 6625 239 12 lt https www logsa army mil etms data A 018850 pdf CFID 30528
80. etc The visiting professional tube jockey did not carry a tube tester he carried a tube caddy a special leatherette covered box with a handle on it and about 200 of the most popular tubes It usually had the colors and logo of a tube manufacturer all over it like RCA GE Sylvania etc He pushed the set away from the wall but not 180 degrees so like a magician he had a blind He would continue to replace tubes until the set worked or it didn t and the chassis had to be pulled to go to the shop uh oh Now if there were one bad tube and he hit it on the third replacement try the two or three he already replaced would stay there and part of the repair job even though the odds were that the first two were good So the bill would list the 3 or 4 tubes plus the travel time and repair time and come to a tidy sum In fairness it was uneconomic to make a house call for a 3 50 tube and 5 00 service call even when gas petrol was 29 cents per gallon here Now that was the simplest form of tube jockey fun There were more nefarious techniques For example some customers learned to keep em honest by insisting on having the old tubes back so maybe they would test them later or at least to foil the situation where the tube jockey replaced good tubes to put in the boxes that he would otherwise retain in his tube caddy to sell as new to other customers However the astute tube jockey might keep known bad tubes to return to the wary
81. ews265 rochester rr com gt Subject Re R 390 HP 8640B usage A 50 dBm level into the multicoupler input is a good median level to start with Vary the level from there as required Even though the unit may be dead increasing the level will usually get enough leakage signal through to get a sniff on your receiver Also presume that the overall gain of the multicoupler around 0 dB A typical multicoupler arrangement is an input amplifier followed by an n way splitter and possibly an amplifier following each splitter output If all outputs are dead some common element is the problem eg input amp splitter Depending on where the problem is located you may have to break the signal path at a strategic point and hose in the generator at the break point to continue your search After you identify the bad stage you will have to drill down from there as they say Date Wed 12 Jan 2011 12 20 29 0500 From wa4aos aol com Subject R 390 Spectrum Analyzer Sorry for the OT question but am trying to make a decision regarding another Spectrum Analyzer for my shop presently have a very nice 8566B SA but the 8566B does not have an internal tracking generator know there are some nice VNA type SA s on the market such as the Array Solutions 2581 and the Ten Tec TAPR unit test gear page 237 Being real partial to HP and Tektronix equipment am looking at possibly buying a 3585 A or B model My understanding is the B model has a
82. external measurements Be very very careful The maximum allowable input level is very low and permanent damage occurs just a whisker above it Best thing to do is solder the BNC cap onto the connector so you re not tempted to try to use the external counter input gt Like most HP gear the 8640B accepts and external 10MHz reference input should you care to gt do that Actually the 8640B uses a 5 MHz external reference At least the civilian version does don t remember offhand whether that is different for the AN USM323 military version Of course a comparator and a couple of flip flops and a filter if you want a sine wave will easily make 5 MHz from a 10 MHz reference test gear page 234 Date Tue 11 Jan 2011 15 43 41 0800 PST From Perry Sandeen lt sandeenpa yahoo com gt Subject R 390 8640B Contrarian opinion lust for the dot matrix displays as used on the HP 8640 If it was new I can see one buying it BUT For a lot less money than a re furbished and guaranteed 8640 one can buy a HP 8656A B or HP 8667A series They are electronically tuned I m pleased with the one have EXCEPT it came with the basic time base which is tuned by a single turn pot Maybe if they had used a 10 turn wouldn t gripe As is it is almost impossible to set 10 MHz within 1 to 2 Hz I m using an external 10 MHz oscillator until can add a better one inside There is space for a high stability oscillator option Considering the gear
83. for the tubes elements to pins and then get some idea of the current flowing through the tube under load Problem 1 the socket is shot Find the 7 and 9 pin socket savers used on the TV7 these look like a tube extender about 1 4 high you plug these in and leave them plugged in Then you wear out you socket saver testing tubes Problem 2 finding set up values for the tube If the tube is listed in the manual you are in If you can find a tube listed in the setup guide that uses the same base as you tube by looking them up in a tube manual base diagram table you are almost in You need to make some educated guesses for the bias setting If you really understand your test circuit you can do setups for tubes on the fly if you know its pin arrangement Testers come in two flavors For this pin on the socket set the voltage to cathode grid plate screen filament Or for this voltage apply it to pin 1 2 3 4 5 6 7 etc Then you need to set the variable voltages Plate and grid bias Test then does a current measurement through the tube The bias voltage is engineered to give a good to bad reading The gas test is relevant Gassy tubes noise Gassy tubes may be microphonic These tubes are also going to fail and maybe cause smoke Shorted tubes are bad and also likely to cause smoke Smoke is bad ask the surgeon general Tube testers will not test microphonics Tube testers will not test noise Tubes should be tested to get the shorts gas
84. for each of the contract numbers What need is the model manufacturer who built the meter along with the info off of the meter face contract number and serial number Any addition info like date codes off of the internal components etc would be a nice plus So far know of the following contract data for the TV 3 and TV 10 series Let s fill in the blanks TV 3 U nothing known TV 3A U nothing known TV 3B U by Hickok with contract number of NObsr 52672 TV 3C U by Jetronic with contract number of NObsr 59586 TV 10 U nothing known TV 10A U by Hickok with contract number of NObsr 71284 TV 10A U by Hickok with contract number of NObsr 71374 TV 10B U nothing known TV 10C U nothing known TV 10D U by Western Reserve with contract number of 85308 SN A4 is in my possession Any non prefixed SN out there What about higher SN s test gear page 267 TV 10D U by Western Reserve with contract number of 87455 Rather than clog the list please email your responses to me The data will be posted on my TV 3 TV 10 page as compile it I m still looking for a few people interested in proof reading the settings data file as put it together I m going to give it about another month and see if can track down some later data I ve still got a few things to wrap up on the TV 4 series project in the meantime Date Fri 06 Apr 2001 20 07 23 0500 From Nolan Lee lt nlee gs verio net gt Subject R 390 TV3 and TV 10 tube tester updat
85. for little or no backlash If remember correctly the main phenolic gear is not spring loaded for anti backlash While you are in there apply a drop only of Caig De Oxit to the tuning cap grounding wipers and just a touch of oil at what assume are ball bearings on the shaft Do report what you find My memory of all this is some years old now If you run into trouble or some mystery may be able to dig out a URM 25 here and have a look at the thing to report more clearly what s there Date Sat 18 Jul 2009 12 02 11 0700 PDT From stoth47 yahoo com Subject R 390 URM 25D dial lamps Anybody happen to know a 10 ea qty source for the URM 25D 325 dial lamps need two new ones searched the usual suspects and found the lamps at Digi Key but they are a non stock item with a 100 piece minimum at 80 a pop have sent a query to Ashley at Kiss Electronics If get a response I ll let the group know what she comes back with Date Sat 18 Jul 2009 15 09 07 0400 From Physicist lt physicist cox net gt test gear page 372 Subject Re R 390 URM 25D dial lamps Newark Electronics Future Electronics Date Sat 18 Jul 2009 16 06 53 0400 EDT From larrys teamlarry com Larry Snyder Subject Re R 390 URM 25D dial lamps These look to be pretty dear Try http shorterlink org 5607 Date Sat 18 Jul 2009 16 11 24 0500 From Dave Merrill lt r390a urr gmail com gt Subject Re R 390 URM 25D dial lamps T
86. from that angle That could very well make a hell of a difference think it might be worth making sure that even the BNC cap is installed on that 200K output of the 25D when not using it too from now on guess that most of us take it for granted that coax is fully shielded when it ain t always try to make it a point to never have any extra coax test cables adapters etc hooked up to anything that I m not using at that very moment do this not so much to reduce clutter fighting clutter is a lost cause on my bench as to reduce the possibility of a repeat of a rather interesting experience that had a long time ago involving an exposed alligator clip test lead an HV power supply a Zippo lighter and me as a ground path could taste the fillings in my teeth Date Sun 09 Jan 2000 15 20 14 0600 From Nolan Lee lt nlee gs verio net gt Subject R 390 DA 121 U amp sig gen stuff gt think there are two problems with having the counter hooked up the fist is that the hookup may not be adequately shielded and may radiate directly to the receiver hadn t really though of the possibility of this was concerned more with the accuracy of the RF voltmeter circuit gt the second is that the loading of the counter may disrupt the output levels This one though of lt grin gt gt check the frequency on my URM 25 the disconnect the counter for those reasons have always disconnected the counter out of
87. give 455Khz One of the options for the 8640B allows audio range freq as well and assume that would be useful for audio stage tests have a HP 606A which seems to work well for the freq range needed for the R 390a know the tech manual recommends using a HP 608 for freq over 10MHZ Is this just for the URM 25 or is the 606A too unstable above 10MHZ too really liked the discussion about the possible sources of noise in gear It puts it in perspective that for most applications the caps are no where near the limiting factor Date Fri 7 Jan 2000 21 45 30 0500 From km1h juno com Subject Re R 390 HP 8640B questions gt The HP 8640B is listed as going down to SMHZ but is there enough gt overlap to give 455Khz test gear page 277 The HP catalog states that it will go down to 450KHz gt gt One of the options for the 8640B allows audio range freq as well While at National they decided to replace the old GR 1001A s with the HP 606A What a disaster with drift dont remember the details but HP replaced them with either a B or made changes to the old ones The replacements were quite nice and drifted less than the old GR also use a HP 608C for above 10MHz and find it acceptably stable when warmed up The attenuator is VERY accurate and leakage is nil when used with good cables use it a lot to test align HF xcvrs for MDS in a 500Hz bandwidth and also VHF xvtrs Some day may break down and get a 8640
88. hacksaw blade and cut the tube near the base Solder up short insulated leads to the socket The hard part is cutting the glass Date Sun 12 Aug 2007 12 17 35 0400 From David C Hallam lt dhallam rapidsys com gt Subject RE R 390 re tube extenders Also check to see if the pins are connected to the correct tabs friend of mine went crazy trying to trouble shoot a Johnson 500 until he found that one of his socket extenders had a pin connected to the wrong tab Date Tue 14 Aug 2007 21 08 45 0700 PDT From Perry Sandeen lt sandeenpa yahoo com gt Subject R 390 Tube extender revisited gt Use a dremmel tool with a glass cutting wheel or special hacksaw blade and cut the gt tube near the base Solder up short insulated leads to the socket test gear page 158 gt The hard part is cutting the glass agree that this can be done and it has been proposed before But why do it Cutting glass with a dremel tool safely is tricky and very slow This I ve done The tube pin material is specially designed to match the glass coefficient of expansion and the internal elements are spot welded to them Not having done it don t know how easy it is to solder wires to the pins Then you still need another tube socket With the army manual adapter all you need are two matching tube sockets and some 18 wire All you do is wire the top socket then thread the wires through the reversed bottom socket solder to the tabs and tri
89. heating are all those bigger than a 6AG7 with large glass to metal seals know an 829 responded to such heating years ago There will always be gas leaks at the seals and running heater filament power alone can raise the getter deposit temperature and make it more effective at grabbing the stray gas molecules And might even cause a bit off circulation inside the tube to improve the odds of those strays running into the getter deposit and would heat the rest of the tube elements to cause them to release molecules better suppose that ALL tubes with glass seals might respond some to a few hours of heater alone to improve the gas situation especially those stored more than a few years Date Thu 14 Dec 2000 11 00 41 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 URM 25 Stability The tubes that respond to heating are all those bigger than a 6AG7 with large glass to metal seals know an 829 responded to such heating years ago There will always be gas leaks at the seals and running heater filament power alone can raise the getter deposit temperature and make it more effective at grabbing the stray gas molecules And might even cause a bit off circulation inside the tube to improve the odds of those strays running into the getter deposit and would heat the rest of the tube elements to cause them to release molecules better suppose that ALL tubes with glass seals might respond some to a few
90. independent vertical channels without alternate or chopped trace facility The timebase is common to both beams The very sensitive narrow band DC coupled vertical amps achieve 1 MHz bandwidth at the low sensitivity end falling to about 100 KHz at 200 microvolts per cm The amps are shock mounted and contain Telefunken 12AX7s that are prized by the audiophoole community Their heaters are run from DC The rest of it HV supply timebase calibrator are typical Tek circuits of the 530 540 type The 502 power supply is a bit different from the 530 540 series in that it uses vacuum tube rectifiers less noisy so there s no time delay relay It s quite a nice scope for DC and audio measurements but useless for RF The amplifier response falls off very quickly above the spec limit remember my 502 as being rather difficult to keep in spec with regard to intensity balance The HV circuitry is set up in such as way that the relative intensity of the two beams is balanced with a preset pot It used to drift quite a bit as it warmed up Not a fatal fault but it could be irritating liked it a lot and used it on the bench for a good few years until a 535A came my way 73 de Morris VK3DOC Date Mon 19 Jul 1999 04 47 00 0700 From Dan Hank Arney lt kn6di groupone net gt Subject Re R 390 Tek scope 502A Call Deane Kidd in Sherwood OR he is listed in the book He has manuals and parts Very good reliable service and the prices are also good H
91. is a good test also have used a very thin narrow bit of paper to Gently touch or prod the movement to check for rubbing or scraping Btw have found that on some Hamfest specials that the glass has worked loose and has pushed the pointer back against the scale sometimes the glass doesn t look like it moved but has been pushed in enough to cramp the pointer and stay jammed so the glass doesn t rattle just another check Joe but sure you thought of this one it s easy to fix but again am sure u check this one because it s a Classic Now further questions Barry Do you have any pet suggestions regarding tools and handling techniques for these ultra delicate manipulations I ve used the blowing technique to check for free movement bits of paper cut to small manipulators re machined nut drivers to reduce over all od and re shaped screw drivers of various breeds and types In some cases I ve had great success but in others seems the most common meter repair problem has been an apparently open coil yuk not a good situation and have not had luck solving that one even with resoldering micro joints so assume in these cases it must be open some place can t isolate other than the coil Just ramblings but meter info always of interest Date Sun 15 Jun 2003 20 36 26 0400 From Gene Beckwith lt jtone sssnet com gt Subject Re R 390 Meter Meister Another great post re the sticky t
92. is a later vintage All 5 millivolts maximum sensitivity 100 MHz The HP 1740 is virtually identical some say easier to use The only specification difference is that the 1740 shows three test gear page 22 traces when displaying the external trigger input and the 465 shows only the external trigger input Their selling prices were also identical The 10X light is triggered by a pin on the ring of the BNC connector on Tek probes There were 475 and 475A The 475 is like a 465 dual trace delayed sweep but 200 MHz flat to instead of 100 MHz for the 465 and 2 millivolts sensitivity The 475 sacrificed the 2 mv range for another 50 MHz bandwidth so was 250 MHz The scope tube on the 465 is brighter and more suited for seeing one shot events even under bright lights The 475 tube is not as good for that and mine was new when bought it have no experience with the 485 a 400 MHz bandwidth scope too pricey when the 475 works there just isn t calibrated well Nor the 466 storage scope All these are analog scopes Its good to find the matching Tek probes they work better than the after market probes but were expensive when new My 475 has not been perfect blew a thin film input attenuator module once playing with high voltage a diode bridge in the power supply failed and a plastic clutch in the delayed sweep switch crumbled Tek wanted 375 for the whole board wouldn t sell the 15 part so carved a new clutch piece from aluminum and
93. is in excellent shape except the meter movement itself The pointer drags against the dial plate ever so slightly near the zero volts end took the meter out expecting to be able to open it and adjust the needle but when got it out of the box found that job to be a little more complicated than first thought This meter has a ring that locks the back test gear page 63 cover of the meter to the bezel outer face plate This is held together with a locking ring The ring has four small slots that assume provide the means for a special tool to unlock the ring by twisting it about 10 degrees The problem is don t have a tool to unlock the ring The shell is approximately 3 7 and the ID of the slots is about 3 8 making the tool that would be used to unlock this ring pretty special Does anyone have experience with this type of meter Any chance of anyone having such a tool to unlock the ring Can it be done with a small punch and a hammer without hurting the meter hesitate to try this but it might my only resort Any suggestions on a makeshift tool to unlock it Any meter rebuilding experts out there Date Fri 08 Mar 2002 13 39 57 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 Need Meter Repair Help Fix into a block of wood brads or screws with the heads clipped off to fit the meter mounting holes Sit the meter over the nails screws and tap the ring with a screwdriver and a hammer lightly Squirt a bit
94. is it to find a low freq option and add it to an 8640B As remember the HP designers _explicitly_ built the 8640B so that the real low end would be 455 KHz or a bit lower just so it _could_ be used for tweaking IF decks know mine goes down below 455 KHz the low end is 447 8774 KHz this morning Mine only has options 1 2 and 3 and so there s no LF option involved Maybe yours needs some retweaking or to be looked at or something certainly don t claim to be anything more than a user operator when it comes to the 8640B From John KA1XC lt tetrode comcast net gt Subject Re R 390 Deoxit Date Sun 30 Nov 2003 10 37 15 0500 I ll ditto Mikes s remark the couple I ve used in the past made it down to 450 KC or so From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 Deoxit Date Sun 30 Nov 2003 10 16 44 0600 agree with mike mine goes below 455Khz as well It has options 1 2 and 3 too but don t think it is any of those options that cause it to do that Date Sun 30 Nov 2003 12 30 58 0500 From James M Walker lt chejmw acsu buffalo edu gt Subject Re R 390 Deoxit Try the Audio output bnc connector and the Modulation Audio output it has the same specs as the regular audio oscillators from HP You just can t sweep the audio frequencies However and am doing this from memory am pretty sure you can get down to around 5 10 Hz at the low end on the HP 8640B
95. just surprising to see the as manufactured poor solderability of the terminal boards It took a lot of effort to find everything The 122 Megohm input Z is quite the thing Just moving my hand near the probe zooms the meter pointer around quite a bit Date Mon 25 May 2009 14 45 38 0400 From Patrick lt brookbank triad rr com gt test gear page 196 Subject Re R 390 HP410B Intermittent s and solder joints Have a MFJ 929 Automatic antenna tuner that the circuit board where all the switches go was covered by some sort of film about half of solder points of the 8 switches 6 contacts each never made contact with the board GREAT QUALITY CONTROL BY MFG after considerable ammount of work removing all the switches scraping the board contact points and resoldering the switches the tuner has performed great Pat Joints some time do get cold with age know my knees and hips are cold Date Tue 26 May 2009 09 24 51 0400 From Bill Kulze lt wak9 cornell edu gt Subject Re R 390 PowerSDR Dave the attenuator is a switched pad of resistors actually about 100 ohms impedance but for this it s ok Just so we re on the same page PowerSDR is software The hardware from them is the FlexRadio You do need a hardware interface to get the 455kHz IF from the R390a to a 12kHz if to the soundcard Have fun with it I ve found it to be an aid in alignment also Kinda acts as a spectrum analyzer where can see the shape of the filters as
96. keep the oscillator running all across each band All fixed capacitors in the tuned circuit should be dipped silver mica that are individually proven to be temperature stable though there may be some temperature compensating ceramics to help temperature stability Variable capacitors can be more stable with hairspring rotor grounds than wiper rotor grounds or by using a circuit where the rotor ground can be eliminated balanced tuned circuit like the SCR 522 VHF receiver Mechanical stability is critical Temperature stability can often be improved by adding insulation on the outside of the oscillator chamber then added a thermostatically controlled heater as simple as a positive temperature coefficient thermistor set to have a transition a bit above the normal internal operating temperature Better heater controls may produce a bit better oscillator frequency stability but the band switch mentioned earlier may negate them all A band switch can be made less of a problem by using a tuning capacitor section per band and an oscillator active device transistor or tube per band so the band switch only handles the output from a low impedance point tube cathode and DC But this turns into a radical redesign Some oscillators tune only the highest band and are divided by analog or digital frequency dividers to reach the lower frequencies If stability is more important that radiated noise the same counter type frequency stabilizers that work
97. longer will pull to the end of it s range that matches up with low end Depending on weather they did high side injection or low that s either the high or the low end of the VCO range Date Mon 25 Mar 2013 10 19 48 0500 From barry williams lt ba williams charter net gt Subject Re R 390 HP 3586 Problem Would you remind me what the Fo rear connector is for My 3586B is in packed up at the moment don t recall using any of the rear connectors for HF LF or VLF work It has been a couple of years since I ve used it have the service manual Getting inside is a major chore due to case construction My internal battery has died and HP says there is a risk of leakage and damage once they need replacing test gear page 408 Date Mon 25 Mar 2013 10 59 29 0500 From Mike A lt mikea mikea ath cx gt Subject Re R 390 HP 3586 Problem According to the manual this output Fo rear connector tracks the center frequency of the bandpass at 0 dBm and 75 ohms nominal Date Thu 18 Jul 2013 22 07 03 0200 From sigmapert lt sigmapert gmx de gt Subject R 390 Nolan Lee s work on the TV 7 tube tester Nolan was also active in the field of military tube testers A remarkable contribution deals with the TV 7x U He prepared an extensive Excel file Date of last update is July 5 2002 You can download the Excel file here http schmid mainz de tv 7_097 xls The following sheets are available Cover Instructions Basing Char
98. many folks trying to find repair parts w o any luck that went w the old trusty rusty URM 25 Particularly interesting was one guy who claimed to have bought 4 broken HP 8640b s and his humorous report about trying to get one working unit from the piles o parts As previously mentioned when left to warm up and stabilize my URM 25 holds frequency well The only thing that was wrong w it out of the box from Fair Radio was no signal in two bands There is so much documentation on how to troubleshoot amp repair the URM 25 that suspect mine will have the missing bands restored in short order Date Sun 15 Feb 2009 21 19 21 0500 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 backlash on URM 25 If yours is a D model not an F then the fix may be easy The frequency knob is on a shaft that goes all the way to the back of the oscillator compartment casting test gear page 371 There at the rear is a single ball bearing and end play adjustment assembly The assembly consists of a threaded bearing seat the bearing and a lock nut Note just looked at the digital copies of the manual have here and cannot a see where the end of that shaft is in the picture b see whether the shaft goes to the rear cover of the casting or if the bearing is inside so that you can see it only once you get the rear cover off If the end play is more than it should be the knob will have backlash as you turn it to adjust the frequ
99. me prerface my remarks by saying that much of what is said about preventive maintenance on the reflector is baloney Take for example the resistor replacers You can t measure most resistors accurately in circuit unless you lift at least one end and if you do that you might as well go ahead and replace it Ditto for the capacitor replacers Unless there is some strong reason to replace a component it is burnt dark brown or black cracked case oil leaking out hot enough to boil water etc leave it alone Just because the case of a capacitor is black or brown does not mean it should be replaced To illustrate how silly that is could say tongue in cheek replace all capacitors with a yellow case Would you do that There are of course a few cases where you should replace capacitors The mechanical filter blocking capacitor of an R 390A is an example of such a case Now don t really believe the story that the R 390A filter blocking capacitor failed in some R 390A many moons ago and the operator switched through all the filters killing all the filters before he discovered what had happened But because don t want to tempt fate have replaced that cap with a disc ceramic cap having a much higher voltage rating in all of my R 390A s And any black case cap in an SP 600 should be replaced immediately before you even turn it on but you can usually see the cracks in the cases of the SP 600 black beauties As for the URM 25D ever
100. members has produced lt http users erols com eengineer add htmI gt test gear page 74 Date Thu 17 Oct 2002 13 15 15 0400 From rbethman comcast net Subject R 390 TS 505 manuals For those wanting the operator s manual and the maintenance manual have them both in PDF form Zipped together they make 711KB Send request to me direct and I ll send them by E mail Date Mon 25 Nov 2002 09 21 36 0800 From Dan Merz lt djmerz 3 cities com gt Subject R 390 xtal wave spikes Hi in looking at the output from the front end high freq oscillator 40 to 60 Mhz xtals on the Mackay 3010 noted double peaks on some of the waveforms though the nominal frequency was ok My first reaction was that this could be symptomatic of a failing crystal though the output works ok and the right signals are received in the radio on the band in use The spike occurs on the downside of the wave kind of a minor glitch as the wave is decreasing Does anyone know what this means or what is causing it Most of the xtals don t exhibit this characteristic but a couple are dead I m going to replace the dead ones MH Electronics says they will provide replacements for 15 ea if I ll send them a good crystal as example of spec s Is this a reasonable price compared to other possible providers thanks Dan From Bob Tetrault lt r tetrault attbi com gt Subject RE R 390 xtal wave spikes Date Mon 25 Nov 2002 10 01 46 0800 Dan The presenc
101. meter now is quite accurate on AC Somethimes feel like the scarecrow from the Wizard of Oz Date Mon 02 Apr 2007 14 33 49 0400 From Roy Morgan lt roy morgan nist gov gt Subject R 390 Tube Tester Repair A request for Tek Scope repair on the Collins list need servicing prompted me to call Bill Waters He is repairing any and all tube testers in Frederick MD It appears that he may be the only one doing this work now For further information email to him William Waters lt ts6550 yahoo com gt test gear page 144 He prefers to do business via email a web site is in preparation He will send his description of services and you can figure out what you want to do Date Mon 2 Apr 2007 14 46 53 0400 EDT From John Lawson lt jpl15 panix com gt Subject Re R 390 Tube Tester Repair Nearer the West Coast I ve have had excellent service and dealings with Roger Kennedy at www alltubetesters com He does complete repair restoration and refurbishment of Hikock Cardmatics Military Weston Sencore Triplett etc etc and can arrange to have meters repaired and re faced BTW have no affiliation other than Happy Customer Date Fri 20 Apr 2007 19 29 26 0000 From Gene Dathe lt dathegene hotmail com gt Subject R 390 Capacitor checkers THANK YOU to all who replied to my post wtb if deck Many offers deck is on the way am currently building up my supply of test equipment and am wondering w
102. meter to 10 then you lower the output level using the microvolts pot Date Sun 9 Jan 2000 19 42 03 EST From DJED1 aol com Subject Re R 390 Signal generator connection questions The problem with the signal generator is that you need a much stronger signal to gate the counter maybe 60 or 80 dB above the levels you want to test at So you have in the case of the URM25 a separate output port with a 2V signal It s tough to shield that much signal to a level below 0 1 microvolt I ll see if can develop a consensus amongst the group on the impedance for the radios think you can always correct the measurement for the matching resistor effects Date Sun 9 Jan 2000 18 15 11 0800 From Ed Zeranski lt ezeran concentric net gt Subject Re R 390 Signal generator connection questions When was in the service Navy we used the URM 25 on a daily basis and as someone posted size was probably in the MilSpec Ever try dragging an HP 608 up ladders on an old tincan to align URR 35 RED receivers The 25 was used on R390 274s etc by using HS 30 phones to do a zero beat at the closest point then using the dial maybe not great but as a 20 year old ET2 all we had Checking the local 25F zero beat with a counter on Hi out was well dead nuts Had not recently thought about the LM comparison though should have as several live here models 10 15 21 as well as some Army 221s and the QST CQ articles on those back to W W II surplus
103. morgan nist gov gt Subject Re R 390 URM 25 D Signal Generator You also need any or all of the following ESPECIALLY Dallas Lankford s Overhaul Notes Hollow State Newsletter Issue 41 Spring 1997 URM 25D Rebuild Notes Supplement about the Terminal Board Courtesy of Ray Mote HSN Issue 34 Winter 1994 95 Short Subjects Balky Modulation Oscillator in the URM 25 by Allan Douglas about the R C T network and padding a capacitor to make it work again E mail from Nolan Lee to Roy Morgan Dec 22 1998 advising to replace the coax cables found with URM 25 s since they are often lossy replacing the coupling cap in the Test Lead to prevent damage to the attenuator and checking all cap and resistor values in the generator URM 25D Overhaul Notes by Dallas Lankford 11 88 revised 1 94 with copy of HSN Supplement from Issue 41 about the Terminal Board test gear page 341 Signal Corps SSTS Operation Sheet 51038 RF Signal Generator Set AN URM 25D Operation and Calibration U S Army Signal Center and School Fort Monmouth N J 17 pages Date Fri 17 Jan 2003 15 10 12 0500 From Mike Sullivan lt vze344qr verizon net gt Subject Re R 390 URM 25 D Signal Generator Roy where can one find all these goodies on the URM 25D From Jerry Kincade lt w5kp direcway com gt Date Sun 19 Jan 2003 13 31 52 0600 Subject R 390 For Sale SG 1144 U Sig Gen Solid state successor to the AN URM 25 series Hi fellow sore wri
104. net gt Date Thu 22 Aug 2002 21 52 27 0500 Subject R 390 Manuals Does anyone on the list need a nice set of manuals Technical Service and Operators for the AN USM 488 scope made by tektronix have the set and anyone who needs it can have it for postage reimbursement In EXCELLENT shape and a shame to see just sitting here 73 Don WB5HAK From wbShak lt wbShak prodigy net gt test gear page 27 Date Thu 22 Aug 2002 22 11 17 0500 Subject R 390 Manuals Gone Subject says it One list member is FAST hi Date Thu 5 Sep 2002 06 05 34 0700 PDT From Rodney Bunt lt rodney_bunt yahoo com gt Subject R 390 Manual for Tek 475 Scope Anyone out there have amanual for a Tektronics 475 Oscilloscope Or better still a link to site that has a pdf documet etc Government releasd document have a dead power supply Date Thu 5 Sep 2002 10 14 22 0500 To R 390 mailman qth net Subject Re R 390 Manual for Tek 475 Scope Go to http Awww logsa army mil etms find_etm cfm and download TM 11 6625 2735 14 1 OSCILLOSCOPE OS 261B V 1 U TEKTRONIX MODEL 475 WITH OPTION 04 There are schematics in this document From Drew Papanek lt drewmaster813 hotmail com gt Date Wed 21 May 2003 15 49 18 0400 Subject R 390 B Dropping Resistance was Drill a Hole Anybody nostalgic for a 535 545 series scope have 5 of them That s a little too much nostalgia for me I already have a 535 Th
105. not as crisp as the 453 454 485 but still an excellent performer IMHO the 453 shouldn t be overlooked if you want a cheap usable scope have one that has been in almost constant use for 30 years without any major repairs needed While collect and use a lot of T amp M gear Tek scopes are the only ones use my love of these fine instruments goes back to 1953 and my dad s 535 Date Mon 29 May 2000 12 58 46 0700 From Larry Shorthill lt rfssi shorthill mindspring com gt Subject Re R 390 probes Well it s been a while so let me see if can think best how to answer this First the 465 and 465B are not exactly the same scope The B means it was a later improvement probably to make it cheaper more reliable or because of some other item like a new feature to combat the competition The 400 series scopes were all portables more like luggabe and some of the first ones were commissioned by IBM for their service men It didn t take Tek long to realize the market potential for this type of service instrument The 453 and 454 and their A and B variants were in this group think the 454A was one of the best portables Tek ever did In the 465 475 485 series the 475 was probably the best the 465 not being as robust it broke too easily at least within the Tek engineering community and it was limited to 1OOMHz BW if remember correctly The 475 had higher bandwidth 200 not sure and the 485 was really fast for the day a
106. one about 50 some ought MHz that s interesting One thing I ve noticed is that they are very susceptible to instability caused by external mechanical forces and it s gets a lot worse worse as the frequency increases The 25F seems to be worse than the 24D or G in this regard If you bump one the output frequency will change Ditto for bumping the bench or moving anything heavy around on it When I ve getting ready to use the 25 take it off of the bench and sit it on wooden seat bar stool next to the bench gt Nolan I ve checked the voltmeter on the 25D 0 0 0 eee Next time you you have your URM 25D apart check the resistors in the modulation meter circuit If R167 R168 R170 or R171 have drifted upwards test gear page 310 more than 5 from their marked values replace them Also check R169 the meter calibration pot for the modulation meter function It s a 2500 ohm carbon pot If it measures much more than 2500 ohms between terminals 1 and 3 replace it too There are some other potential problems that can cause some hair pulling when you attempt to calibrate the RF voltmeter function Check R129 the 100 ohm resistor that one end of is soldered to the back end of the 200K front panel BNC connector It s probably out of spec from being soldered and unsoldered a few times Since the 200X jack is used to set the output levels during the calibration procedure you want R129 to be as close to 100 ohms as possible If you have one
107. one for channel B It appears the B channel is set to 50ms and the A channel is set to 500ms Someone mentioned that it s also apparent that none of the horizontal display buttons are selected and in this condition it may default to A channel If so then a 500ms sweep time may be much more in line with what s shown given a 50ms shutter speed suppose I ll find out in a week or so Thanks for the advice guys Date Tue 10 Nov 2009 17 18 56 0500 EST From larrys teamlarry com Larry Snyder Subject Re R 390 OT bought a scope gt Someone mentioned that it s also apparent that none of the horizontal gt display buttons are selected and in this condition it may default to gt A channel If so then a 500ms sweep time may be much more in line with gt what s shown given a 50ms shutter speed That would ve been me still think you re going to be ok There s a Y group out there TekScopes populated by quite a few former Tek folks It s a great resource and very helpful There s a copy of the USAF TO on the edebris bama mirror Lots of good stuff in there Once you have it in hand feel free to yell if you have Q s Date Wed 2 Dec 2009 15 52 02 0000 GMT From Robin Filby lt robin filoy yahoo co uk gt Subject R 390 HP 410C Original manual Does anybody have an original manual for a HP 410C VTVM which they would wish to sell Or does anybody know of a source for originals NOT CD copies please Thanks in
108. out to Mouser and get on with it Date Thu 20 Jan 2000 13 06 55 0500 From Warren W Thomas lt wtw rti org gt Subject RE R 390 AN URM 25 Capacitor Replacement I m in the same boat in that have my URM25D all in pieces on my bench being very generous with that term In addition to the components below that Lankford specifically identifies others have been mentioned either in Hollow State News or on this newsgroup as worthy of replacement Specifically C132 25 or 35 MF electrolytic depending on model mentioned by someone who had a physically leaky unit Here the recommendation of one of our most knowledgeable components gurus is to use a solid tantalum as a replacement ordered mine from Mouser last night but unfortunately don t have the stock number here at work test gear page 297 C135 C136 Someone had C135 go and fry his attenuator Why not replace them while you have the buffer amp out used a 2KV disk ceramic for C135 and paralleled up a couple of silver micas for C136 While don t think the jeopardy of C131 popping is too great it s easy to replace while you re in there Take a look at R152 R153 R154 and R155 especially to see that they are in tolerance A highly recommended procedure to check all resistors to see that they are in tolerance May want to measure the ripple on the output of the power supply to see if the filter caps are still good measure about 0 15 millivolts ripple across t
109. people that think they gave birth to them or liberated them from Wright Patterson Date Mon 3 Sep 2001 20 26 05 0700 PDT From John Kolb lt jlkolo cts com gt Subject Re R 390 Opinion on HP 606b sig gen I ve seen several HP606A s recently for less than 100 The B version has an added input where DC voltage can fine tune the frequency Used as a phase lock input from a synchronoyzer or as a sweep or perhaps FM modulation input If you are down towards the San Diego area have a HP606A for pickup only certainly not drop dead beautiful for 50 Needs either new tubes or new capacitors in the modulation section but output attenuator works fine Date Sun 30 Sep 2001 10 16 08 0400 From Barry Hauser lt barry hausernet com gt Subject Re R 390 R390A tube chart amp PUZZLEMENT Last night asked about that sub as this 62 Imperial has a 6CB6 in the 6DC6 socket and Les replied that it was a good sub Are there any downsides have some NOS 6DC6 s here to swap back But that s not the puzzlement This radio appears to be in very good cosmetic shape wiring looks very good very clean etc but haven t pulled any modules as yet HOWEVER it is the worst case in maybe 50 receivers and accessories of various types I ve found in terms of tube condition on delivery think Five out of the seven 5814A s show shorts on position 3 on my TV7 D U Two test good All are RCA except one of the good ones a GE
110. pins with the tester set for a 6L6 tube and providing 5 mA current in the plate circuit The only way to tweak the tester was to shift the position of a magnetic shunt plate on the meter to change it s sensitivity But aside from tweaking the meter his test gave an indication of how well your tester indicated the benchmark reading Replacement of bad resistors is the next remedy if the meter is way off All this stuff is discussed on Padgett s Hickok page which just casually checked to see if it mentioned calibration In reality 83 tubes seem to last a long time think I ve replaced one in 15 years so consider the ss diode replacement an emergency measure until an 83 can be found Maybe can find the ss sub and provide a little more info best regards Dan Date Mon 27 Mar 2006 20 06 37 0500 From Steve Hobensack lt stevehobensack hotmail com gt Subject R 390 Re HP410B rectifier tubes had a similar problem with my ME 26D U a 410B clone AC probe The measured voltage was way off It was a shorted capacitor just after the needle and in front of the 2 01c diode tube A replacement cap can be fashioned from a disc ceramic cap and a dremmel tool If you need that special cap dremmel off the coating on a suitable capacitor plus the leads until you end up with a pill shaped ceramic cap It was tricky to install The cap is easily ruined by trying to measure over 300 vac Date Wed 3 May 2006 00 10 17 0400 EDT From John
111. plus a few plug ins A 150 Tektronix 465 is what sits on my bench and it does almost everything need from a scope The RS probe scope works well enough for some basic measurements but the small pixel count 16x32 on the built in LCD display limits the measurement resolution when used without an external display You get better resolution 6 bits when connected to a PC but find it cumbersome to use a PC to display scope waveforms on the bench Bandwidth is 5 MHz there is only one channel and adjustability is limited It does have several nice digital scope features when connected to a PC and it also has a DVM mode AC and DC volts but not ohms or current think it would be good as an ultra small scope for travel and also for use in locations without AC power if it were teamed up with an existing laptop and a good set of batteries If you ever need to troubleshoot equipment mounted on top of a tower this is the scope to take with you on the climb up test gear page 26 It s a fun tool to use and would buy it again just for the novelty value but think I ll keep that 465 on the bench Date Thu 04 Jan 2001 10 16 04 0600 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 R 390A Manuals and O Scope gt Anybody have any experience with the Tek 564 storage scope Yes a small bit have an RM 564 here that worked when put it waaaay back in the Junque Boxe about 7 years ago Some observations 1 The 65
112. prices were the same just all but a couple words of their specifications felt the 1740 was easier to use That was the first HP scope that ever competed well with Tek Date Thu 01 Jun 2000 09 22 05 0500 From Dr Gerald N Johnson lt geraldj ames net gt Subject Re R 390 Need Advice on O Scope test gear page 15 Tek 456 or HP 1740 Some figure the 1740 is easier to learn to use They are identical in performance 100 Mhz dual trace portable delayed sweep Good enough DC calibration to dispense with VTVM on the work bench 73 Jerry KOCQ From Nolan Lee lt nlee gs verio net gt Subject Re R 390 RE Need Advice on O Scope I ve been a fan of the 54x series Tek scopes for a long time and still am Recently the 7xxx series has gotten affordable now have five of the beasts a 7603 a 7613 storage scope and three 7704A s one of which has PS problems that can t figure out and will probably end up being a parts hulk I ve also got a couple of dozen or more plug ins and some assorted residue plug ins and parts Larry Ware told me before got involved with the 7000 series that they were addictive as hell He was right They re even more addictive than the old 5xx series gt Add to that believe its a 300 mhz frame but don t hold me to that number The 7704A is a 200 MHz mainframe My primary one is a cherry one with Option 9 which is a 250 MHz mainframe The standard 7704 is a 150 MHz mainframe One of the reasons t
113. pull out There is a much larger braid contact area compared to the standard UG connectors was having troubles trying to use a coax cable between my home brew double shielded fixed output 0 dBm generator and enough attenuation to get down to 415 dBm with imperfectly shielded receivers Using no flexible cable was successful RG 55 previous mil spec double shielded RG 58 size before RG 223 leaked One cable grabbed leaked a lot One end fell off when applied Johnson s wire test A sharp tug If the wire stretches or the end comes off it wasn t wire all the way through A tough test but quick Its clear that the fancier HP or Times or Andrew corrugated solid metal cables are probably better for measuring set up found that the BNC connector and BNC cables and adapters leaked different amounts according to tiny position changes at 50 MHz on my signal generator Most metrologists despise BNC for that reason especially above 200 MHz The bayonet lock just doesn t anchor the mating parts well TNC and N do much better about consistency When l m trying to achieve 145 dB of shielding I m pushing the envelope Date Sat 08 Jan 2000 20 50 50 0500 From Roy Morgan lt roy morgan nist gov gt Subject RE R 390 Signal generator connection questions test gear page 280 iia time to ask where one gets good double shielded RG58 style coax and good connectors RF Connection http www therfc com The R F Connection 213
114. putting them in The routine for the D model is similar but different caps have an F model too URM s for all occasions That one still modulates as needed The C has the more common preliminary failure mode intermittent modulation Starts up when you switch it on then quits Switch the mod off for a second then back on works again for a while Phil don t Know if that F manual will be much help As recall Nolan Lee s explanation there are substantial differences even between some adjacent letters like the C and the D If my foggy memory serves best as it can think he said the F returned to the C style circuitry though the front panel doesn t look the same Whichever it is though a buck or two in caps fixes it Did you try switching the modulation on and off to see if there s anything there at all Date Wed 19 Dec 2001 21 01 39 0000 From Phil Atchley lt ko6bb elite net gt Subject R 390 URM 25D info have a URM 25D here with all acc in the lid that think may need some tlc It does work and generates a carrier seems remarkably accurate in frequency where I ve tested it BUT it appears to have no 400 or 1kKHz modulation Any common failure modes that should look for first downloaded the manual for the URM 25F from the BAMA site but haven t looked at it yet How does the 25D test gear page 329 compare circuit wise and mechanically to the 25F It appears that this would be a very good generat
115. quite a change from the URM 25 The 8660 was one of the first synthesized generators mine has a binary display and can be set to the nearest cycle The one got has a plug in that covers 01 to 110 MHz so it matches nicely the capabilities of the URM 25 struggled with how to test this thing expected that couldn t zero beat to better than 10s of cycles because the receiver audio will cut off at very low frequencies so how to tell if it worked as specified decided to try and measure with an offset so that had a beat note of a few hundred cycles then put the frequency counter on the audio output and measure the beat to a cycle It worked very well could measure an offset against WWV down to about 1 cycle when the modulation was off After warming up the generator set it to 15 000300 fed it into the R 390A along with WWV and measured the audio beat as exactly 300 cycles So it looks like the old 8660 still is working well checked the attenuator and it seems to be working OK so tomorrow will measure the sensitivity of the receiver which the URM 25 measures as 0 3 microvolts or so The 8660 goes down to 0 03 microvolts so should be able to tweak the receiver as never before The only drawback is that the 8660 unlike the URM 25 is definitely not portable it s about 65 pounds It may be easier to carry the receiver to it than vice versa Ed WB2LHI Date Sat 26 Feb 2005 10 38 57 0800 From Jack Antonio lt scr287 sbcgl
116. separate signals that are near each other For scanning a whole band 100 300 Hz is best and 1 kHz will do in a pinch For looking at 20 kHz of spectrum 10 30 Hz is much better And for looking at one signal in a 2 10 kHz bandwidth 3 Hz is very useful Also older analyzers are often not well calibrated as to frequency so you end up spending a lot of time and energy doing that manually with a generator and counter The 3585 reads accurately to 0 1 Hz It also has a tracking generator which is invaluable for design or characterizing filters or any number of other things It s all about what you need it to do And while you re thinking about that also try to imagine things you might be able to do with a SA that you haven t thought about yet and what cababilities those would require With any of them you want a CRT that doesn t have a million miles on it The newer analyzers typically keep track of on hours and on off cycles It pays to familiarize oneself with the operators and service manuals of the models under consideration so one can give the seller step by step instructions to get this information and run basic diagnostics Date Sun 15 Aug 2010 12 56 04 0400 EDT From frankshughes aim com Subject R 390 Spectrum Analyzer status Thanks for all the advice and tips very informative The Spectrum Analyzer arrived Now just have to learn how to use it the fun part Thanks to KZ5AW bought one of these http www amtronix
117. someone will get a plug n play URM 25D somewhere By coincidence was using my URM 25F this afternoon to check out another coincidence a piece of Heathkit equipment an SB 610 monitor scope The scope was DOA Meticulously assembled the assembler had neglected to solder two connections one of them on the power switch But that s not all a 330K resistor was burned through in the HV section My cap checkers only go to 600 volts the caps are 1200 and 1600 volts so didn t bother A 15 mfd 1600 volt tubular tested infinite on my ohmmeter but apparently was failing at the operating voltage as a replacement resistor started to burn up so pulled the plug and that cap No suitable replacement on hand made up an unsuitable one a bundle of six 2kv 01 disks uuuugly Replaced the replacement resistor and the thing works after a fashion There s some unevenness in the trace which think is the scope s self analysis telling me it would really rather have a tubular of the right capacity There are also a pair of similar 10 mfd caps that make up a voltage doubler along with a pair of cylindrical selenium rectifiers Probably should replace those too So my question is where to get 1600v or 2K tubular caps of recent manufacture It s a bear to wade through the online catalogs Meanwhile this monitor scope could be set up for a range of IF frequencies using alternative components that were supplied with the kit This one was apparent
118. sover net gt Subject R 390 FS Hewlett Packard HP 410 C VTVM Hi Gang have an extra HP 410 C VTVM which is the lab grade VTVM that Collins used on the line and in the engineering department when the S Line was produced It is one of the recommended pieces of test equipment in the service manuals Unfortunately do not have the AC RF probe and have priced the meter accordingly at 75 00 plus shipping Any interest from the group before post it you know were From JM CO lt jmerritt2 capecod net gt Subject Re R 390 FS Hewlett Packard HP 410 C VTVM Date Mon 14 Oct 2002 15 14 41 0400 The AC RF probes for these models were matched to the particular unit during manufacture Once the probe is lost it is not possible to plug in just any random probe and have the meter function properly Over the years have seen many 410 Cs for sale without probes but have Never seen a separate probe for sale anywhere Wonder where they go From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 FS Hewlett Packard HP 410 C VTVM Date Mon 14 Oct 2002 14 13 09 0500 test gear page 72 Is the probe for the 410 C different from the probe for the 410 B Does the same this is the correct probe for this meter rule apply for the 410 B didn t think so but might be wrong Date Mon 14 Oct 2002 22 07 59 0200 From Heinz und Hannelore Breuer lt hbreuer debitel net gt Subject Re R 390 FS Hewlett Packa
119. swears by the General radio units and I m still kicking myself for test gear page 54 missing one The 25 is OK for working on old BA sets zero beat on the set is dead nuts accurate but that 40 606 is more dependable long term Date Thu 21 Jun 2001 02 02 24 0400 From Norman Ryan lt nryan intrex net gt Subject Re R 390 Thanks and Restoration Update Hi Kim and group No need to be ashamed of using low budget test equipment for R 390 alignment especially if one is strapped for dough or has other priorities like feeding a family My first signal generator was an Eico 324 with manual picked up for next to nothing at a flea market It had the usual Amphenol microphone connector which replaced with a BNC as soon as got it home and recapped it to be on the safe side Since you have to zero beat the SG to the R 390 during most of the alignment procedure instead of the other way around an accurate SG freq readout isn t a big issue Getting the IF deck s frequency right involves tuning a radio to 455 MHz and zero beating the SG freq to it before injecting its output into the R 390 then retuning similarly for the two variants 467 and 443 MHz for stagger tuning You can do a decent job aligning the R 390 with a basic unit like the Eico 324 It s reasonably stable after warmup Diode load is easily read from an analog meter also cheap and basic sold the Eico later on and put the proceeds toward a URM 25D from Fair and love it Th
120. that is slightly lower in value like 99 ohms use that one as a replacement By the time it s soldered into place it ll probably be 100 ohms Also check the value of R130 the 500 ohm resistor that feeds the input of the attenuator It s a film type resistor located on the buffer amplifier subassembly It should be 495 to 505 ohms max It s another negative temp coefficient resistor so if it out of spec you ll have to do some searching to find one If you run into problems not being able to adjust R172 high enough to get a full 2 volts out of the 200K jack when you re making the calibration adjustment then R144 a 4 7K resistor has probably drifted up in value Replace it with one on the low side of it s 4 7K value It ll give you more adjustment If that doesn t do it check the 10K R128 between pins 5 and 7 of the 5726 tube to see if it has increased in value If so change it This should take care of any problems you have providing that the meter is in spec If not holler back Date Thu 14 Dec 2000 09 19 37 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 URM 25 Stability It was done in jest was messing with him and poking fun since he lives up where it snows and don t gt If your counter has a ovenized crystal and you gt start it from dead cold and mean cold it could show gt drift of maybe 200 Hz within the first 2 minutes That could vary a lot depending on the on the frequency of the master
121. that the adapters that came with it had late design high quality dipped resistors that hadn t changed in value at all The adapters that used conventional looking carbon composition resistors need to be checked for out of spec resistors Comparing the schematics and parts listings from the URM 25G and H manual my D model is actually a G model with it s extra 12 volt transformer winding and a zener diode regulated filament supply for the oscillator tube The power supply in the G runs noticeably hotter than the D model but doesn t drift as much with changing line voltage I m looking for a copy of the schematics and parts listings from the manual on the URM 25 models later than the H Date Sun 09 Jan 2000 03 09 04 0600 From Nolan Lee lt nlee gs verio net gt Subject R 390 URM 25D stuff gt ET to ask where one gets good double shielded RG58 style coax and good connectors like which particular BNC connector is the one of choice l m still using my little hoard of NOS King silver gold teflon insulated BNC connectors that picked up from a NASA auction Exceptional quality but expensive as hell and cost prohibitive if you can t find them surplus started getting low on them a few years back and checked into their prices They were well over twenty bucks apiece retail Some of them topped thirty dollars each You d stand a better chance of seeing hell freeze over than ever seeing me spend twenty dollars for a BNC connector
122. the autoranging types that have problems with such measurements could imagine this could happen depending on the rate at which it tries to range the reading but it would seem that it should eventually settle down He tried it with two different digital meters and couldn t get a stable reading sometimes use this measurement method on 390a parts hi Hopefully waiting for illumination Dan Date Mon 12 Jul 2004 16 51 50 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 DMM bounce What frequency are your voltmeters calibrated for Date Mon 12 Jul 2004 23 28 43 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 DMM bounce If you are using a trusty VACCUM TUBE instrument then you will have no problem with vacuum tube impedances A modern super duper high speed auto ranging DVM will to just a little nuts trying to measure the resistance of your 360 Henry inductor Some of them at least drive the device under test with a constant current source This is fine for a capacitor or resistor On an inductor the current ramp gives you a voltage ramp Up goes the voltage and it auto ranges Even if it runs a constant voltage it will still auto range if it s fast enough The coil will look like an open circuit at first so the things little brain decides to go to a higher resistance scale In either case you can get a situation where it just bounces back and forth with no tendency to settle at all Simple sol
123. the lower ranges but is throwing the high range off don t think could add or remove L on that upper range coil given the way it is made Anyway it sure was fun to get back into working on a piece of BA gear again Other than being dusty and needing some pots cleaned some missing screws replaced and new line filter caps it looks like a very nice generator think it has all Hewlett Packard branded tubes as well Date Mon 25 May 2009 12 13 33 0500 From Don Reaves lt don reatek com gt Subject Re R 390 HP410B Intermittent s gt get go Removing the old gucky solder then liquid flux and heat seemed to gt give a ok joint It was surprising to see that kind of problem inside of an HP gt instrument Not unheard of once found the problem with an HP 200R with intermittent output to be that a b line leading from the power transformer had never seen a hint of solder The wire was wrapped on the transformer solder lug and it probably worked OK for a few years then slowly oxidized A slight variation of the Stockdale technique to restore operation of a BC 375 worked on the HP 200 before the proper repair was implemented http www youtube com watch v TBXmVqcAP6M at about 2 30 in this clip Date Mon 25 May 2009 13 37 51 0400 From Jon Schlegel lt ews265 rochester rr com gt Subject Re R 390 HP410B Intermittent s Finally got all the flakies fixed calibrated the instrument and the 410B now works great It was
124. the PTO oscillator tube shield A bit of manual study will reveal what the PTO frequency should be test gear page 374 Later come to understand the mixing scheme and the frequencies expected at different parts of the radio Locate the test points on the RF module and inject signals expected starting nearest the IF output NOTE If you are using the URM module that has a single capacitor in it replace that thing before going very far It may well be leaky and let B into your URM attenuator or let grid voltage leak off from the radio Date Wed 23 Feb 2011 23 50 08 0600 CST From nryan mchsi com Subject Re R 390 Non A alignment question Nice tip Roy and thanks for that think you are referring to the CX 1363 U test lead dashed over to mine and checked it for leakage and it s OK It happens to be one made using new components in an identical housing but it never dawned on me that vintage units should be checked for sure The test lead can be viewed on page 2 10 of the URM 25D manual TM 11 5551 D It s simply a blocking capacitor network comprised of a 1 mF 400VDC capacitor in parallel with a 510 pF 500VDC mica capacitor Vy 73 de Norman KG4SWM Date Tue 14 Jun 2011 07 16 23 0200 From Heinz Breuer DH2FA lt dh2fa darc de gt Subject Re R 390 USU 1 gt Long time that am looking for schematics and manual of ROHDE gt SCHWARTZ USU 1 SELECTIV MIKROVOLTMETER Hello Alex if you can t find it anywhe
125. the TS 505 The meter end of the lead had a short 1 inch plastic selves While the user end of the lead had a 4 or 5 inch plastic sleeves The tips were plated brass and threaded as 4x40 The tips would bend easy and break even more easily Any one know where we can get the probe tips from today Date Tue 22 Mar 2005 11 34 46 0000 From rbethman comcast net Subject Re R 390 TS 505 Manual try http home comcast net rbethman ts505 zip THIS will let you download it had one of those SENIOR moments Of course trying to KEEP up with THEIR naming conventions HAS driven to the precipice Date Tue 22 Mar 2005 07 43 49 0500 From James M Walker lt chejmw acsu buffalo edu gt Subject Re R 390 TS 352 Batteries Those are BA31 4 5 VDC and BA30 your classic D cell 1 5 VDC they are still available at various places and prices gt http www voicenet com sgphoto batteries htm http www ibsa com estore browse_category asp category_id 397208 test gear page 117 For the reason the meters were surplused out The battery manufacturing process included mercury http www emedco com emed2 resource msds msds_view asp pd ba amp pf bk Ihr Duracell makes a 4 5VDC battery that will fit in the spaces set up for the BA31 and connectors to adapt it inside theTS 352 are available at Radio Shack have and use two TS352 VOMs find the ability to measure up to 5000 VDC quite handy Find all of the manuals for the tester at http
126. the radio under test enough to distort the measurement With the Heath Lab signal generator was able to measure a receive sensitivity of 0 03 micorvolt for 10 db S N N know this measurement wasn t valid because the generator and the receiver were on opposite sides of the room and there was no coax connecting them just leakage from the generator Date Fri 7 Sep 2001 00 49 16 0400 From Tom Leiper lt twleiper juno com gt Subject Re R 390 recommendation for rf signal generater test gear page 325 That s true They take it so seriously on the URM 25 that the high level output jack is actually switched and I think grounded when nothing is plugged into it What did was to modify an in line 6 db BNC attenuator by taking it apart and removing the resistors that were in it and just leaving the 50K series resistor After reassembly connected it directly to the generator and ran RG 55 double shielded RG 58 from the output of the attenuator to the voltage potential undulation rate meter Date Thu 6 Sep 2001 23 06 40 0700 PDT From John Kolb lt jlkolo cts com gt Subject Re R 390 recommendation for rf signal generater gt lt snip gt What did was to modify an in line 6 db BNC attenuator gt by taking it apart and removing the resistors lt snip gt Exactly the thing to do But did you mean the attenuator started life with a 50K series resistor Doesn t sound right unless it s like 25 Ko
127. the same time leaving the signal generator at the low levels needed for the radio For example may need the generator set to 1mV but the counter needs about 100mV to drive it I m not a EE design engineer but think a simple circuit could accomplish this Are there op amps that perform in the 100kHz to 30mHz range that could be used in a simple circuit for this Am dreaming to think this is a simple endeavor From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 Signal Amplifier Needed Date Mon 22 Mar 2004 12 58 47 0600 I ve gotten a few suggestions Apparently it is possible to build an external amp to get enough gain It became glaringly obvious however that the best solution is to use the high power output on the signal to drive the counter while using the attenuated output for the radio was thinking the high power 2V output was not ON all the time but apparently it is and this is one of its best uses Being a Neanderthal don t always know a wheel when sees it test gear page 102 Date Mon 22 Mar 2004 15 41 55 0500 From Roy Morgan lt roy morgan nist gov gt Subject RE R 390 Signal Amplifier Needed The X200K one oh yes You didn t say you had a URM 25 I assume you do It appears to me from the schematic that both the X200K output jack and the attenuator have signal when the output switch is in either of the X200Kpositions 10 kc to 300 kc or 300 kc to 50 mc Note ho
128. their HP 8640B really think mine is the best non synthesized RF generator I ve used in almost 40 years of pushing elctrons and making stuff work My AN URM 25D is a fine piece of test gear but the 8640B is IMHO at least one cut above From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 Suggested Test Equipment for R 390A Alignment Date Tue 8 Apr 2003 09 18 58 0500 Welcome While the AN URM 25 is supposed the instrument of choice it isn t required A stable signal source with sufficient attenuation that can be matched to the various test points are all that is needed The test procedures frequently mention the accessories that are part of the AN URM 25 s list of accessories but they are not absolutely necessary used an AN TRM 1 to align my first R390A I ve since acquired a nicer GeneralRadio that prefer and plan to sell the AN TRM 1 Some guy had a large inventory of AN URM 25 generators a while back Perhaps he still has some Ask any question s you want The guys on this list stand ready to help Date Tue 8 Apr 2003 14 52 07 0400 EDT From Paul H Anderson lt pha pdq com gt test gear page 80 Subject Re R 390 Suggested Test Equipment for R 390A Alignment like the URM 25 because to be blunt I m not the brightest bulb when it comes to repair of RF requipment and like following the exact instructions with the exact equipment called for But if you can ask questions and unders
129. there test gear page 6 Date Tue 20 Jul 1999 09 52 55 1000 From Morris Odell lt morriso vifp monash edu au gt Subject Re R 390 Tek scope 502A gt Of interest is that there are transistors in this scope kid you not A gt 2N301 and 2 2N214s Germanium think Even then sand was trickling into our hardware They are there to regulate the DC heater supply to the input tubes Come to think of it it would be hard to imagine a 6 3 or 12 6 volt DC heater supply regulated by tubes In their bigger scopes Tek used a tube regulated 100 volt DC supply to feed lots of heaters in series All the serious work in the 502 is done by tubes gt have no idea on earth what shall ever do with this thing But a lab was gt being shut down it was in like new condition and kinda followed me home It s enough that you saved it At a recent antique radio auction here a 502 hardly raised a bid and may ultimately be trashed A couple of us who knew its significance were quite upset if didn t already have one would have bought it Date Mon 02 Aug 1999 09 25 59 0700 From Lawrence Mayhew lt imayhew ibm net gt To W Li lt wli u washington edu gt forgot to tell you about the 502 having two independent vertical axis only electron beams For some low frequency work it was impossible to use a chopped vertical to view two signals that had been multiplexed There was another Tek scope with two beams the other was the 5
130. there and talk to them and tell them that you re looking for odd lengths of either new cable cut too short screwups or some long runs of used cable that they ve removed during site upgrades etc gt Nolan sure glad you mentioned the attenuator would never have thought of taking it apart I ve disassembled both of mine cleaned and adjusted the contacts and lightly lubed the shaft and detents Watch you don t loose the detents when you take it apart Also be very careful when you measure the values of the little 60 some ought ohm 1 8th watt resistors or the resistance of the contacts It don t take much to smoke the resistors and you ll just about need a parts hulk signal generator to find replacements gt I ve checked my URM25 against an HP 8405A vector gt voltmeter and find that the actual microvolt millivolt output reading gt isn t particularly accurate i e the URM meter says one thing and the gt HP says another All of the resistors in the attenuator are 1 negative temp coefficient ones The original accuracy spec on the meter is probably 2 or so of FS The overall accuracy spec for the RF voltmeter circuit of the URM 25D is 10 according to the manual Way more than close enough for any non lab type BA use Realistically the difference between 9 and 1 1 uv when you re shooting for a precise 1 0 uv probably isn t worth worrying about test gear page 285 The 10 accuracy spec seems on the high side for it suspect th
131. they won t like it but a customer s crucial communications links won t degrade or fail Some of us just like to mess with measurements and enjoy knowing our equipment is working right For example a while ago got a General Radio Precision Capacitance Bridge that joins a similar inductance bridge here don t yet know if they are working right but expect to check them whenever can have no earthly reason to measure inductors or capacitors to 0 05 percent On What can we do about all this For many of us doing it at home is a fine thing Getting an instrument and an invoice for a big amount back from a Cal Lab is likely not in our future At home we can check frequency counters and generators with very small errors receiving the WWV EB signals at 60 kc is the start of a system that gets you well within the specifications of most oscillators found in frequency counters and generators For a couple hundred dollars you can buy a standard oscillator surplus from the cell phone industry as understand it that is extremely accurate Measuring resistance inductance and capacitance is a bit more complicated but you can find reference standards at hamfests or on the web that will make a start at a set of known values As you dig into the methods of measuring these values you will begin to understand the value of the setup and the methods you use and how they affect the results It takes a small table full of inductance standards to cali
132. they disappered off the web and epay My unit has 2 different tags on it the front panel has a urm 25d with new screws and the case has a urm 25j 19687 Is there anyway of knowing which one have and what version is a URM 25J Date Wed 7 Nov 2001 07 22 57 0500 From Barry Hauser lt barry hausernet com gt Subject Re R 390 Tags on urm 25d The geneology of the URM 25 is a bit complicated Best bet is to post a photo of at least the front panel so some of the experts can take a look at it But I d also call Fair Radio while they still remember your unit think RJ is the URM specialist there and would have checked your unit or Dave might know Fair includes a partial manual copy with the checked units they most likely matched up the correct version or as close a match as they could with the variety of manuals they have on file Offhand I d suspect that a nice D with a banged up case got a different one but there are those new screws One thing to test is the modulation Many of these give out after a while and go back on if you switch modulation off and on again If this happens there are a few caps to replace which Fair might have already done on your checked unit There is a compendium of tips gleaned from past posts on Al Tirevold s R 390 FAQ site http www r 390a net URM_25 txt Might be something of help there Date Wed 7 Nov 2001 11 24 51 0500 EST From Paul H Anderson lt pha pdq com gt Subject Re
133. those fins though One thing that was curious about is a 2pF cap across both tuning caps it is a push pull oscillator wonder what it s purpose is and whether it might warrant replacing I have a dipped silver mica for it but didn t put it in place as didn t want to replace what appears to be a factory part if it isn t bad Date Sat 1 Aug 2009 14 30 24 0500 From Barry lt n4buq knology net gt Subject Re R 390 OT Problem with HP 606A linearity Interesting update changed the points where am setting zero Instead of setting them at the absolute endpoints used points closer to the points where the error was the worst used 600kc instead of 530kc for the low end and 1700kc instead of 1800kc for the high end It makes the entire scale have a maximum error of 0 8 with each endpoint being out 0 6 and 0 6 respectively It starts out a little high goes low briefly then back to high until nearly the upper end where it crosses back to low again Not sure if this is the best way to do it but it does get me closer know the R390A s IF transformers are peaked something like this not at the endpoints but somewhere near the end Maybe this is good for calibration procedures as well Hope this isn t too OT for this reflector Date Wed 5 Aug 2009 07 47 23 0500 test gear page 207 From glwebb gundluth org Subject Re R 390 Series 4 Megger haven t used my Biddle Mark III Floor and Footwear Tester f
134. trickling into our hardware gt Those old Tektronix 500 series scopes were true works of art Wonderful gt examples of quality craftsmanship My manual has a nice little pocket in the back with a sheet entitled Calibration Record Filled out by hand and signed by a Frank Glass Calibration Engineer and Ralph Sawyer Quality Control Engineer in April 1959 I ve not seen one of these for later scopes so maybe this was an early innovation There was also a mod kit for the 502 that provided the usual variable time cm control My scope has it installed have no idea on earth what shall ever do with this thing But a lab was being shut down it was in like new condition and kinda followed me home Jan Skirrow Date Mon 19 Jul 1999 17 39 52 0500 From Tom Norris lt badger telalink net gt Subject R 390 Re Tek scope 502A Indeed recently moved up to a job at Arnold AFB here in TN During the performance of my duties electronic instrumentation tech have run across dozens of assorted Tek tube type scopes The 502 is a popular scope in some of the older test cells because as one engineer put it They work well they keep their cal better than some of the newer gear and they do what we want them to do Most are in older control and test areas but are still in daily use AEDC is a fun place to work especially for a gadget junkie like me Check out their web page at www arnold af mil for more info on what they do
135. were made in the 80s but I m not positive As another list member said it s no Tek or HP but it does sweep and it was cheap It s relatively light and if need a portable sweep function generator sometimes grab it particularly if I m worried about damage theft etc generally use a Tek SG504 40 MHz sweep function generator if I m not expecting the going to get tough because can also conveniently bring other useful TM 5xx modules Not that the Tek 5xx stuff is all world class mind you some of the modules are plenty quirky The DM501A DMM for example puts so much hash and other digital garbage out of its input that you can t get it anywhere near a radio and the frequency counters tend to be fussy about triggering Best regards Don test gear page 189 Date Sat 21 Feb 2009 22 08 55 0500 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 Leader Equipment Some thoughts on this A hand held instrument will usually be somewhere else when you want it A larger sit on the shelf thing is likely to be where you last left it Rack mounted stuff is almost certainly where you last saw it Don t spend a lot for test gear Certainly don t buy new stuff Nowadays you can get really good stuff that s a bit older and still working just fine for not much money Hamfests ePay wherever Hamfest season is coming right Itsy bitsey miniaturized computer controlled instruments may have loads of features but
136. which fail short rather than open This is true of all paper capacitors whether tubular or postage stamp format Mica capacitors tend to fail open but failures of any kind are MUCH less common than with paper capacitors In my opinion the most useful capacitance checker of all is a simple Voltmeter a VTVM preferably or a 20 000 Ohms per volt VOM otherwise Go through the various stages and compare the tube pin voltages with the charts shown in the service manual A tube socket extender makes the job much easier 1 Too high a voltage on the control grid suspect leakage on the capacitor coupling the grid to the preceding plate 2 Too low a screen grid voltage suspect leakage on the screen bypass capacitor 3 Too low cathode voltage suspect leakage or more likely a dead short on the cathode bypass 4 No AGC unreliable AGC or bizarre AGC voltages such as zero or positive suspected one of the many AGC bus bypass capacitors is leaking 5 AGC hangs up suspect an AGC bypass or time constant capacitor 6 Noise limiter doesn t work except when off time constant capacitor in the noise limiter or AGC circuit That being said the chief problem with any capacitance checker is that you have to disconnect one side of the capacitor to test it If you have gone to all that trouble you might as well disconnect the other side and replace the capacitor orange drops are a favorite among R 390 A enthusiasts and be done w
137. will need a variable HV supply and a VTVM The HV supply can be also usd to rebuild an existing electrolytic if that is your wish another controversial subject My homebrew variable HV supply employs a small Variac feeding the primary of a junker TV transformer test gear page 170 appropiately fused and user insulated and a simple LC filter Parenthetically l was astounded at how NONE of my Orange Drops leaked and how many of the vintage oil filled and waxed paper caps leaked at 250VDC Additionally found that 7 pin and 9 pin tube extenders handy in measuring pin voltages when the receiver is operating DeOxit is a fabulous product when used judiciously on contacts Much has been posted on how NOT to use this chemical but wager we all still use it frequently found that a roll around clear plastic 52 inch tower set of drawers meant for clothes is a dandy way to store spares tubes caps manuals what have you Mine is attached to a plywood base for rigidity and rolls around on four commercial grade 4 inch rubber wheels All the various probes leads etc needed for the test equipment are hung on the back of the plastic tower on large clothes hooks Goes where you need it and occupies a small of amount of valuable floor space One thing plan is a similar roll around arrangement using a short 19 inch rack to have the test equipment all together and off the workbench Date Sun 27 Jan 2008 13 53 25 1100 From Pete Willi
138. you have some good notes about maintenance please send them to me Date Sat 28 Mar 2009 22 35 42 0700 test gear page 191 From Leigh Sedgwick lt bipi comcast net gt Subject R 390 Warning off topic but technical have an old Fluke 77 digital voltmeter The specifications in the manual do not specify a frequency range for AC measurement accuracy Does someone on the list know the frequency limitation of this meter I m assuming it is around 500 hz or is it even lower than that Sorry for the off topic post but know there are some very knowledgeable folks on here Date Sun 29 Mar 2009 02 55 54 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 Warning off topic but technical According to the operator s manual which is available for download on the Fluke web site see 75 77 for the original 77 http us fluke com usen support manuals default htm prodcategory OBS the rated frequency range for AC voltage and current measurements is 45cps 1000cps except that for the lowest voltage range it is 45 500 Hz found the manual by Googling fluke 77 manual download Date Sat 16 May 2009 22 09 02 0500 From Barry lt n4buq knology net gt Subject R 390 Sources for HP410C AC Probe Anyone know of a source for the AC probe for an HP410C besides eBay My new one doesn t have a probe Date Sun 17 May 2009 00 40 48 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject R
139. you run into problems not being able to adjust R172 high enough to get a full 2 volts out of the 200K jack when you re making the calibration adjustment then R144 a 4 7K resistor has probably drifted up in value Replace it with one on the low side of it s 4 7K value It ll give you more adjustment If that doesn t do it check the 10K R128 between pins 5 and 7 of the 5726 tube to see if it has increased in value If so change it Date Sun 09 Jan 2000 09 45 49 0600 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 Signal generator connection questions Nolan Lee wrote 2 haeeeeetteeettttes Adding a second 50 gt ohm coax in parallel for the counter would totally change the output gt impedance of the circuit wouldn t it If so that could make a hell gt of an error in the calibration of the RF voltmeter circuit That s not nearly the problem that putting 10 dBm into a piece of coax cable to radiate a bit and then go to the input amplifier of the counter where its boosted to 3 or 4 volts peak to peak square wave inside a single shielded at best probably not really shielded at all box to radiate directly to the single shielded at best receiver input Date Sun 9 Jan 2000 11 32 05 EST From DJED1 aol com Subject Re R 390 Signal generator connection questions think there are two problems with having the counter hooked up the fist is that the hookup may not be adequately shielded and may rad
140. 0 From Bernard nicholson lt vk2abn bigpond net au gt Subject R 390 Tube testers Guys tube testers are for wimps the best tube tester is the circuit that the tube is working in you can check the voltage drops across plate amp screen amp cathode resistors and with a modicum of mental arithmetic remember that you can easily see what is happening in a circuit in a well designed radio tubes don t work very hard at all The original signal Corps Specs for the RCA AR88 calls for the set to perform to its specification with ANY or ALL tubes at 30 emission This is the reality this is the reason that tubes are rejected on the tester but the set is still working OK was trained in communications in Carrier Telephony we used to keep detailed maintenance logs of every piece of equipment And performance checks were done regularly this gear used literally thousands of tubes and many tubes were only changed after many years when the specs were no longer achieved Back in these times people who resorted to tube testers were called Valve or Tube Jockeys They were looked down upon and were figures of fun Tube testers were used in Australia as a marketing tool you could take all the tubes from your radio or TV and test them in the shop where they could sell you some more Very convenient Surely if we have Pretensions to own and Maintain an Esoteric R390A one can learn about mutual conductance and amplification factor etc then all you need i
141. 0 hp 410B VTVM for working on my R 390A According to my manual instruments with serial numbers above 003 31433 use the EA53 Date Sun 4 Jan 2009 11 09 31 0600 From Tisha Hayes lt tisha hayes gmail com gt test gear page 172 Subject Re R 390 R 390 C101 and C103 Caps The surge voltage on that cap will happen before the series regulators get heated up so a quick measurement at turn on will be needed to find out what you need Here is where the DVM is best set aside and a VTVM with moving needle used am a big fan of VTVM meters for high Z measurements where the loading on a Circuit by a DVM really throws off a reading for the ease in peaking a level like the diode load level by watching the swing of a needle and when measuring RF levels with a high frequency meter some of the HP 400 family meters are great for this are the best choice The use of a really good DVM on peak measurement readings of B may actually be a better choice in some cases To measure very fast peak rises on a non high impedance circuit still use a top end Fluke DVM with a fast capture option and with peak hold capability have found that the measurement accuracy of a good Fluke rivals a capture and hold oscilloscope for measuring fast transients and gives me a fast capture peak hold capability when measuring current as well gt From an aesteic standpoint a tube meter with a mechanical movement is what the R 390 was originally designed
142. 0 7 500 15 000 70 1 750 3 500 8 750 17 500 80 2 000 4 000 10 000 20 000 90 2 250 4 500 11 250 22 500 100 2 500 5 000 12 500 25 000 110 2 750 5 500 13 750 27 500 120 3 000 6 000 15 000 30 000 Miles B Anderson K2CBY 16 Round Pond Lane Sag Harbor NY 11963 Tel 631 725 4400 Fax 631 725 2223 e mail k2cby optonline net test gear page 406 Date Tue 7 Aug 2012 11 51 11 1000 From bernie nicholson lt vk2abn bigpond net au gt Subject Re R 390 R 390 Digest Vol 100 Issue 4 Hi To all On the subject of tube testers most military radio gear and test equipment from the tube era will have a list of electrode voltages in the Handbook relating to the potential on various pins have always located faults by measuring the voltages and checking against the list one can see what s happening by for instance measuring the voltage drop across a screen resistor and plate resistors and cathode resistors if there isn t a voltage drop NO current is flowing and mental arithmetic will give you a picture in your mind of what s happening or not In the 1960 s when tubes were the go people who resorted to tube testers were known as TUBE JOCKEYS and were looked down upon by REAL service men When you look at the Signal Corps specs for a receiver like the AR88 they state that ANY or ALL of the tubes can be down to 30 emission and the radio still has to perform to spec most tubes in the 390A are running VERY conservatively Whe
143. 0 years and while use my Sprague TO 6 mostly feel pleased when I m able to identify a problem by using his approach Date Tue 6 Mar 2012 18 39 51 0800 From Chris Kepus lt ckepus comcast net gt Subject Re R 390 AN URM 25D Repair Info Dallas Lankford Maintenance notes Here are a few more special Hollow State News PDFs to post on your site if they are not already there think most if not all were done by Reid Wheeler according to the Word doc explanation which contains a screen shot from the original Barry Hauser web site HSN Accessories pdf HSN Accessoriesindex pdf HSN Hammarlund pdf HSN Hammarlundindex pdf HSN R390 pdf HSN R390index pdf HSN TestEQ pdf HSN TestE Qindex pdf Best of Hollow State by Reid Wheeler doc Date Tue 6 Mar 2012 21 12 12 0600 From Don Cunningham lt donc martineer net gt Subject Re R 390 Capacitor tester At the advice of a good friend built a capaciter ESR checker from a kit available several years ago got mine from Dick Smith Electronics DSE believe at the time but can no longer find that It will read the ESR of a capacitor in or out of the circuit which is a real plus for checking these old rigs sure wish had bought two of the kits while they were available as the commercial ones see for sale are VERY pricey If you can find one of these that someone built and never used or even an unbuilt kit highly recommend the use of those Date Tue 6 Mar 20
144. 00 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 Signal generator connection questions a eaa sine uate He recently sold me a piece of cable marked gt M17 84 RG 223 Mil C 17 Times Microwave Systems 68999 AA 3413 gt It has two layers of silver plated braid shield and a solid silver plated gt center Conductor eeeeee test gear page 281 gt That s exactly the description of proper RG 223 Anything else is a lie gt In the oddity category just got three BNC type Tee connector blocks gt which are triax coax that is they have a three conductors one center and gt two separate coaxial shields They are marked DAGE 95712 4972 1 don t think the triaxial connector was intended for UHF or microwave More for very sensitive instrumentation at DC and HF It doesn t work with RG 223 needs the shields insulated from each other gt One last note if you are measuring very low signal levels and have your gt counter hooked up to the High output on the URM 25 or similar output on the later HP 606 s you are fooling yourself and your receiver On my HP 608F that is better shielded than the TS 510 used to use find its also important to have a shield cap on that high level output to approach 25 dB above the MDS of a good VHF SSB receiver Date Sat 08 Jan 2000 22 26 11 0600 From Nolan Lee lt nlee gs verio net gt Subject RE R 390 Signal generator c
145. 000 16 46 51 0600 From Nolan Lee lt nlee gs verio net gt Subject R 390 military tube tester data beta available The Excel version of the settings data for the TV 2 series military tube testers is slowly getting there and now covers everything from the OOA to the 809 that have data for There s over 1800 lines of settings data so far and have a hell of a long ways to go I m dreading the xxxx four digit tube numbers For the source material I m using the roll chart out of my TV 2B and the June 1966 edition of the little 72 page TV 2 series supplement book TB 11 6625 316 12 1 If you have later source material contact me I d like to include any settings in it that are lacking from the material that have At any rate a BETA of the file is available from http www acadiacom net nlee beta beta011 zip It s a zipped archive containing an Excel workbook format file and contains nothing except the settings This is a BETA Error checking of the data is non existent or nearly so There ARE errors in the original roll chart and the test gear page 255 supplement book I ve caught some of them I ve probably also added a few thru typos on my part VERIFY the data before you use it lt snip gt don t mind putting this type of information together and making it freely available This is my third such project involving military tube tester data BUT could really use some outside help in checking the data for errors typos miss
146. 00V per Lankford notes C162 0 1 400V all paper C163 0 1 400V replace all with Orange Drops C164 0 01 300V C165 0 01 300V C166 0 2 120V i C167 0 2 120V C130 0 01 300V paper replace with 2KV disk ceramic C132 25 25V electrolytic replace with solid tantulum C133 0 022 200V paper C135 0 01 300V mica replace with 2KV disk ceramic C136 510pF 300V mica C131 150pF 300V mica this one will probably break when you deal with R119 so have a spare available Calibrator Oscillator VTIVM C139 0 022 200V paper More input is needed Anyone else care to share their 2 cents Date Wed 26 Jan 2000 01 59 09 0500 EST From Norman Ryan lt nryan duke edu gt Subject Re R 390 RF deck restoration lt snip gt At ahamfest the other weekend found a crank knob similar in style to the original skirted vernier knob but without the skirt and a bit larger on the URM test gear page 302 25D Makes changing frequencies much much easier No more URM 25D wrist Date Tue 1 Feb 2000 08 11 00 0500 From Warren W Thomas lt wtw rti org gt Subject RE R 390 Mobil 1 Synthetic is a bargain Reference your lubricating potentiometers I ve just about buttoned up the URM 25D that s been my winter project yes I m very slow and unfortunately my hand eye coordination is about fifth rate hi The microvolts pot in my URM was scratchy and in particular was very nonlinear up near the top end Obviously carbon had
147. 06 Aug 2012 14 17 46 0500 From Randy and Sherry Guttery lt comcents bellsouth net gt Subject Re R 390 Testing tubes r392 test gear page 404 gt have a TV 7 What is method to convert the 1 120 quality reading to umhos If you Know what umho the tube is rated at and you assume that 100 quality is that number or near enough one can make some reasonable calculations gt can you just build a speadsheet for this and use it as a referral That d be one way but I d probably want to compare quality reading against the same tube s umho reading in a TV 10 or TV 2 better yet gt Or better question what s the best way to make the conversion would take a bunch of tubes several new tubes representing several values of new emission and then a couple hand fuls of older well used tubes see what they read in a TV 10 or TV 2 and a TV 7 and that should give you some confirmation of quality to umho for your tester just what I d do Date Mon 06 Aug 2012 14 29 09 0500 From Randy and Sherry Guttery lt comcents bellsouth net gt Subject Re R 390 Testing tubes r392 gt There is one flaw in blasting crud off tube elements Don t know what you re referring to the blast I m talking about is to hold down the P3 emission test to apply normal test voltages then just ever so lightly just tap the OZ3 button You ll get a boost of HV meant to fire the gas in an OZ which will hopefully arc
148. 07 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt 4 lt https www logsa army mil etms data A 018850 pdf CFID 3052807 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt ELECTRONIC MULTIMETERS TS 505A U AND TS 505B U AND MULTIMETERS TS 505C U TS 505D U lt https www logsa army mil etms data A 018851 pdf CFID 3052807 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt 018851 lt https www logsa army mil etms data A 018851 pdf CFID 3052807 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt TM 11 6625 239 34P lt https www logsa army mil etms data A 018851 pdf CFID 3052807 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt ELECTRONIC MULTIMETERS TS 505A U TS 505B U MULTIMETER TS 505C U AND TS 505D U FSN 6625 243 0562 lt https www logsa army mil etms data A 029316 pdf CFID 3052807 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt 029316 lt https www logsa army mil etms data A 029316 pdf CFID 3052807 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt TM 11 5511 lt https www logsa army mil etms data A 029316 pdf CFID 3052807 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt 5 lt https www logsa army mil etms data A 029316 pdf CFID 3052807 amp CFTOK EN 567ad9a35eec9d6b CAF2D549 D78E 341E 81C4EBBEFCOEA931 gt ELECTRONIC MULTIMETER TS 505 U TO 33A1 12 55 1 Let m
149. 1 Jun 2001 08 02 55 0700 From Roger L Ruszkowski lt rlruszkowski west raytheon com gt Subject Re R 390 Deam old 505 agree them old 505D s are OK have 3 on the bench The green rubber test lead for ohms dies after time on one of mine replaced mine with a general black test lead The battery VM from RS are OK but when want the truth switch the 505 on and use it can always find the 505 on the bench Where do we get the probe tips for them these days You can pick them up with the cover for 20 25 dollars Ain t nothing inside you can not fix yourself My big problem is finding a good voltage to use for calibration Date Thu 21 Jun 2001 12 10 36 0400 From Norman Ryan lt nryan intrex net gt Subject Re R 390 Thanks and Restoration Update Gee wonder if we were looking at the same TS 505 U It was pretty rough and broader in width which must account for the space needed for batteries No need to acquire such a unit as later versions run on line current only The TS 505B U is a worthy unit little different from the TS 505D U Each has a schematic inside the case for clarifying differences The circuit grounding is different and the DC AC probe in one of these versions doesn t require a resistor if recall correctly minor variations in other words I ve not seen an A or C version if such exist Don t despair if you come across a B while your heart is set on a D the last version because the B is
150. 1 is very simple in the chassis areas all the real guts are in the plug ins the 564 main frame is more complicated for sure 2 Power supply high voltage in particular most troubles show up here DAMPNESS is your enemy Was it Dr Jerry or some other fellow who taught at an EE school they had to get all the 561 s out of storage two months prior to expected use and into the dry air conditioned spaces to dry out before they were run Otherwise they would simply not work have a 561 that like a lot but its trace is gone its on the to do list 3 Fan Noisy Maybe a modern fan would be better you got to have a fan in it though 4 Plug ins There is one vertical plug in that uses a hard to find compactron If yours works fine If not buy cast off plug ins for the tube EAS wants 45 or so for the tube The plug in uses two 5 CRT s The 564 CRT is of course unique If it s blown find another scope They are reported to have only moderate life My RM561 has been my work horse scope here for a long time The knobs are big enough to see and get hold of Since it is the rack mount version it s flat not too high and supports any heavy thing care to put on top of it An RAL receiver for instance Too bad its trace is gone have what may be a pulled HV transformer here got to check part numbers If it s the right one may soak it in dry air with dessicant for a month or three and put it in From wbShak lt wbShak prodigy
151. 10C is plug in not hard wired like the 410B Date Sun 17 May 2009 14 06 36 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 Sources for HP410C AC Probe lt snip gt By the way you don t have to use an EA53 for most things you ll want to do a 6X5 will work fine Note that most HP 11036A probes that you find on the market today will need a new EA53 so make sure you know where to find one and budget accordingly before buying a used probe Date Sun 17 May 2009 13 15 04 0500 From Barry lt n4buq knology net gt Subject Re R 390 Sources for HP410C AC Probe Does anyone know if the 410C can use either the EA53 or 2 01C know the 410B has a rheostat to allow adjusting the heater voltage for either diode but am not familiar enough yet with the 410C to know if the heater voltage can be adjusted for either diode test gear page 193 Date Sun 17 May 2009 14 22 46 0400 From rbethman lt rbethman comcast net gt Subject Re R 390 Sources for HP410C AC Probe do NOT believe the HP 410C has a pot for voltage adjustment It is drawn directly from the 6V supply Date Sun 17 May 2009 10 46 37 0800 From Scott lt scott becklawfirm com gt Subject Re R 390 Sources for HP410C AC Probe A 6X5 sounds a little big for use in a probe how about using a 6AL5 double diode with both sides in parallel A 6AL5 is only good for about 400 volts rather than the 1000 volts that the EA53 can stand but
152. 12 20 34 11 0800 PST From John Saxon lt johnbsaxon yahoo com gt Subject R 390 Capacitor tester Thanks test gear page 395 Wow Did come to the right place Thank you so much guys for the very helpful comments a lot of good advice and a lot to think about really liked Bob s comment about taking an inventory of my radios will do that will record the manufacturer and serial number posted on the front panel and see if can determine the builder of the modules Thanks again guys and will probably become a pest real soon Date Wed 7 Mar 2012 16 35 41 1100 From John Kidd lt u453902 hotmail com gt Subject Re R 390 Capacitor tester Hi all Dick Smith Electronics has gone the way of Radio Shack cell phones TV s etc No longer available however a revised version is available The Blue ESR Low Ohms Meter the latest and best Bob Parker design and successor to the famous Dick Smith ESR Low Ohms Meter http www anatekcorp com blueesr htm have no connection to them have a DSE version that built and happy with Date Wed 7 Mar 2012 01 13 17 0500 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 urm 25 notes and a bit more Thanks for posting those notes NOTES 1 The Lankford overhaul notes were not published IN the hollow state news They were offered as a separate item for sale BY the HSN folks in about 1988 The cost was a dollar think A small number of
153. 19 It was built for the AEC to view phenomena associated with the nuclear tests in Nevada It s bandwidth was over 1 Gigahertz without sampling or other cheats Date Fri 18 Feb 2000 07 28 24 0400 From Guido E Santacana lt laffitte prtc net gt Subject R 390 Oscilloscope Question TK 502A Know that this is not R390 stuff but where else can go just became the owner of a nice Tektronix 502 double beam oscilloscope but no manual One beam is working just right but the lower beam is missing Is there anyone in the list familiar with this scope In any case it will eventually be in the service of my R390s Date Sat 19 Feb 2000 09 55 27 0500 From Christian Fandt lt cfandt netsync net gt Subject Re R 390 Oscilloscope Question test gear page 7 don t have a manual handy but we used 502 s A s and B s at work for years back in the 70 s and 80 s The circuits for each gun are virtually identical With an identical signal on each input you can start by tracing back from the grid cathode anode pins up to the front end and see where the sig is dropped You should note that the bandwidth is 500KHz Absolutely great for audio and VLF but pushing the limit when even checking the 455 KHz IF sigs on the 390 might pick one up someday if it works nearby to haul away in the car and the right price Date Mon 22 May 2000 20 31 28 0500 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Instruments At 07 53
154. 400 volts is plenty for most applications and the 6AL5 is tiny by comparison an also offers similar heater to cathode capability Date Sun 17 May 2009 11 38 20 0700 From Michael Hardie lt mike46 shaw ca gt Subject R 390 HP 410C AC Probe There was an article in ER magazine a few issues back on homebrewing a probe for the 410C think a 6AL5 was one of the possible tubes but increased probe capacitance was a factor Date Sun 17 May 2009 14 35 38 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 Sources for HP410C AC Probe The 410C does not have a filament voltage adjustment at least the ones have seen don t but you could easily enough modify one to supply 5v for a 2 01C Date Sun 17 May 2009 15 13 17 0400 From 2002tii lt omw2002tii nerdshack com gt Subject Re R 390 Sources for HP410C AC Probe You re absolutely right the 6AL5 is what had in mind The 6X5 is an octal power diode Using just one of the 6AL5 s diodes keeps the capacitance down and raises the high frequency limit of the probe a bit Best regards Don Date Sun 17 May 2009 15 13 30 0400 From rbethman lt rbethman comcast net gt test gear page 194 Subject Re R 390 Sources for HP410C AC Probe The 410B has TWO versions depending on ser no The 410B I have does NOT have probes hard wired There is a jack panel on the underside of the front Amm of my probes are removable I m trying to locate the DC pr
155. 410B VTVM for working on my R 390A was digging around in my attic above the shop shack and came across my old HP 410B No tube in the probe of course Has anyone successfully modified the probe to use a solid state device or do need to keep looking for a EA 53 Date Sun 23 Mar 2008 23 46 10 0400 From wabate lt wabate verizon net gt Subject Re R 390 hp 410B VTVM for working on my R 390A would not want to change to a SS diode as tempting as that might be A 1N66 etc would be OK but you would loose a lot Diodes are limited to about 20 vac and 250 MHZ but the 2 O1C can handle over 300 volts depending on frequency The upper frequency limit is over 700 MHZ Hard to duplicate that with a SS diode unless a 20 volt limit is OK for your app The 410 B should use the 2 O1c not the EA 53 unless it has been modified BTW have 2 O1C NIB Trade Date Mon 24 Mar 2008 03 27 59 0400 EDT From John Lawson lt jpl15 panix com gt Subject Re R 390 hp 410B VTVM for working on my R 390A Sam have several of these NOS write me off list if you need one Date Mon 24 Mar 2008 07 38 03 0400 From Barry lt n4buq knology net gt Subject Re R 390 hp 410B VTVM for working on my R 390A don t think that s correct HP built the 410B for both diodes in different probe configurations Date Mon 24 Mar 2008 08 12 53 0400 From David C Hallam lt dhallam rapidsys com gt Subject RE R 39
156. 415 here In the U S A this is 208v One thing should say is DO NOT check capacitors that have a lower working voltage than 500 marked on them as they are likley to be damaged by the meggar also it is possible to charge up capacitors with the meggar and get quiet a shock also DON T check ELECTROLYTICS as they don t like AC had a very noisy IF module in a 390a and when meggar tested the bypass caps they were ALL leaky they were the axial black ones with the coloured bands around them after replacing them it is a different radio once had a tektronix 500 series CRO and the timbase would not work got it from the gov surplus auctions it had an unrepairable tag on it checked every component in the time base and couldn t find a problem but it refused to oscillate then disconnected one end off every component in the time base and trigger and holdoff circuit and meggar tested on testing a 500pf mica cap it read 500megohms this was the culprit the timebases were Miller Integrator timebases and they rely for feed back on the stray capacity of the tube and that 500meg resistor stopped in its tracks venture to surmise that not many instruments would show this fault so you can see that meggars are very handy with valves OR what you guys call TOOBES BUT KEEP IT AWAY FROM THE SOLID STATE HI From Derek Cohn WBOTUA lt vibroplex mindspring com gt Date Sun 8 Feb 2004 11 34 45 0600 Subject R 390 Boonton Signal Gener
157. 5 44 0400 From Barry lt n4buq knology net gt Subject RE R 390 Tube testers didn t stay at a Holiday Inn last night but do use my Hickock 752A from time to time Guess that make sme a wimp too Date Tue 26 Jun 2007 14 40 05 0400 From Joel Richey lt richey2 mindspring com gt Subject R 390 Tube testers test gear page 153 Many years ago when I was a young shaver my father had a radio shop and when came home from school looked forward to fixing radios mostly the all American 5 kitchen radios open filaments and once in awhile a real challenge replacing a filter cap One day got to the shop and there were 2 to be fixed the first one a Philco all the tubes were lit so went to the big Hicock tube tester and tested all of em they all tested good took the rx outa the cabinet and grabbed the voltmeter and check all plate and screen voltage everything looked good worked on that radio for 3 days the 4th day my Pop came up to me and handed me a box with a 12BE6 and said put this in and said had checked all the tubes and their are all good put the tube in and 45 seconds later it was playing from that doay to this would not use a tube tester for anything like the gentleman said they are for wimps buy a book and learn how things work and take you tube tester to the land fill the fact the military uses em should answer all your guestions Didn t mean to ramble on but you get the picture Date Tue
158. 9 16 55 26 0500 From Larry Shorthill lt r41656 email sps mot com gt Subject Re R 390 Tube testers On the other hand if a tube tester says a tube is bad it may be bad and if it says it is good it may be bad The operation of the tube in the actual circuit is the best indicator of whether the tube is good or bad Gassy tubes and shorted tubes may be an exception to this but an example of an indicated bad tube working in a circuit is with the PTO 6BA6 which probably acutally works better with a tired tube than with a new tube Less drift etc That circuit doesn t age tubes very quickly and doesn t demand much from them either Tektronix made curve tracers and other things for testing tubes way back when but those who were in the know there always used good old tube substitution into the actual circuit to determine whether a tube needed changing And again a tube that won t work in one circuit may actually work fine in another see note above on 6BA6 test gear page 247 Date Wed 03 Nov 1999 20 16 32 0500 From Barry Hauser lt barry hausernet com gt Subject Re R 390 I F module Is there any relationship between a tube with grid emmision and one going microphonic Or are these situations generally independent of each other Date Fri 01 Oct 1999 09 45 0700 PDT From rlruszkowski west raytheon com Subject Re 2 R 390 Tube testers do not know about turkey tube testers The trick is to get the tester set up
159. Any paper capacitors should be replaced with mylar or similar capacitors By definition the paper capacitors are bad Date Tue 17 Sep 2013 07 34 43 0400 From Bob Camp lt ham kb8tq com gt Subject Re R 390 Tube Testers The military tube testers are all fine for testing the tubes out of an R 390 Prices are silly high 200 for a TV 7 About the only time they really shine is when you have a stack of gear that was left on well after the first tube failed The result can be that 2 3 s of the 40 tubes in an instrument are dead and you have 10 of them to fix by 5 pm They also can be a help in confirming what you already know from basic troubleshooting A tube tester depending on it s design does not test all the functions of a tube Most do some very simple tests An open filament will indeed fail Hmmmm tube is cold hmmm Past that they give free advice worth what you paid for it A tube that tests good probably will work unless it s leaky A tube that tests bad may well work fine for another 10 years A tube tester gives you one more piece of gear to maintain and calibrate It s also one more thing to lug around why like the small TV 7 For the money you can buy a many lifetimes supply of all the tubes in the radio Swapping tubes is at least as good a fix as using a tube tester Date Tue 17 Sep 2013 09 38 56 0700 PDT From Johnsay Johnsay lt groundwave yahoo com gt Subject R 390 Tube Testers I
160. Aug 2005 14 43 11 0500 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 Tube Tester The best tube tester is a working radio of course but beyond that would stick with one of the Mutual Conductance type testers I think got that right I m using a B amp K 747 The last commercially built tube tester I m familiar with It s a modern tube tester if that means anything It won t test some of the old 4 and 5 pin tubes though Date Sun 7 Aug 2005 10 32 11 1000 From bernie nicholson lt vk2abn bigpond net au gt Subject R 390 tube testers have been repairing instrumentation with tubes in it since the 1960 s and have always been of the opinion that the best tube tester is the circuit that the tube is in it is easy to check the parameters of the circuit by measuring the voltage drops in the circuit i e across screen resistors cathode plate resistors ect with the mental application of Ohms law the currents are easily seen if no current is flowing the resistor is open circuit or the tube has no emission its as easy as that and all you need is a voltmeter never substitute a tube until find a reason for problem in my tool box have a selection of tube extenders so voltages can be read easily above the chassis these are all home made from plugs and valve sockets there have always been people who had pretensions to being technicians and used to endlessly swap tubes around in Australia we used to r
161. B myself lve used them many times at work over the years and they are nice IMO stay away from the early synthesized sig gens phase noise is horrible for weak signal work Date Sat 08 Jan 2000 07 22 49 0600 From Jerry G Kincade lt w5kp swbell net gt Subject Re R 390 HP 8640B questions My mil version 8640B AN USM 323 will reliably go down to 427 kHz with excellent stability but only if let it warm up for at least 15 min or so before trying it Before that time it simply drops the output and the display to zero below about 475 kHz use it with no problems in R 390 SP 600 alignments at 455 do not however trust my unit s display last two digits are a bit flakey after warmup so always T the output it to my HP 5328A ovenized counter during use A good sig gen my only major gripe is its noisy cooling fan likely due to a zillion hours of use but will fix that one of these days Probably will need a replacement counter or display board one of these days also l m sure it will be fun finding one of those Date Sat 8 Jan 2000 08 43 17 0500 From Warren W Thomas lt wtw rti org gt Subject RE R 390 Signal generator connection questions gt I ve found that one of the best things that anyone that plays with gt very low signal levels can do for their URM 25 is to replace the gt coax of the three jumpers Ditto for the internal piece of coax that connects to the attenuator pad My URM25D is spread
162. Beauties of Death also some are Black BODs although have not located any of the Black ones in the R 390 series The 67 EACs have some good Sprague Vitamin Qs and Aerovox caps So we have to look at different ways to test AND determine which issues you are going to find and have to deal with Date Wed 07 Mar 2012 08 53 22 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 Capacitor Tester Miles makes excellent points They are certainly not erroneous It becomes a matter of how one chooses to perform tests The Brown Beauties are definitely prone to failure and are essentially a known and automatically get replaced That being said This also is why it is important to know precisely which radios were built by whom and the specific date of contract 67 EACs do not have the aforementioned BBODs Brown Beauties of Death also some are Black BODs although have not located any of the Black ones in the R 390 series The 67 EACs have some good Sprague Vitamin Qs and Aerovox caps So we have to look at different ways to test AND determine which issues you are going to find and have to deal with test gear page 397 Date Wed 07 Mar 2012 09 29 41 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 Capacitor tester Thanks No question of coming to the right place Serial numbers are less important than the manufacturer and the specific contract date Modules are very likely a grab bag o
163. C modes however it reads quite low about 30VAC where it should be seeing 120VAC think this is just a calibration thing and can fix that just thought I d pass this along in case others may have experienced non working AC probes and not realizing it may just be an incorrect heater voltage setting Check the diode in your probe first though Barry N4BUQ Date Tue 21 Mar 2006 09 25 38 0500 From Tim Shoppa lt tshoppa wmata com gt Subject Re R 390 HP410B rectifier tubes It s also possible that a lower filament voltage makes the tube last longer and makes emission be more stable predictable slower drifting Not that I m saying you or the internet or HP is right or wrong would ve expected that boosting filament voltage would ve improved emission and resulted in too high of a reading compared to your old 5VAC calibration It is very odd for a filament to fail in a way that it doesn t get hot when it gets the same voltage that it always did but that boosting the voltage gets it to some emission but not as much as it used to Is there any way you can measure the voltage really close to the tube or measure the current through the filament circuit compared to spec I d be very suspicious of bad contacts cables etc Date 21 Mar 2006 15 07 50 0000 From n4bug knology net lt n4buq knology net gt Subject Re R 390 HP410B rectifier tubes There may be other factors involved here agree was measuring the volta
164. D U in my possession now thanks to a fellow list member That means that I ve started on a settings file for the TV 3 and TV 10 series like those that I ve done for the I 177 TV 2 TV 4 and TV 7 series tube testers just finished working up a parts order that I ll place later today l m going to replace the electrolytic and paper caps along with all of the carbon composition resistors in the TV 10D U The metal film and wire wound ones are all fine but a couple of the carbon ones have drifted upwards well out of spec I m replacing them with 1 metal film models The meter movement tested accurate within 7 and the error is linear may or may not pull the meter apart and correct the error As it is or will be after replace the caps and resistors this tester has good potential as a test platform for compiling and testing the data Since was already involved in some research for a possible TV 7 to TV 3 TV 10 settings data conversion project I ve got enough information to get the project off of the ground What I m looking for right now is copies of any manuals or roll chart data for the TV 3 and TV 10 series that don t already have A current list of the materials that have access to is posted on the TV3 and TV 10 page on my web site at http www acadiacom net nlee Photocopies or scans are fine Email me before you file attach any scans though I m not interested in anything that has been OCR d I ve had rotten luck with OCR and set
165. DC Range 5 to 600 000 CPS distortion less than 0 5 below 500 kc output 160 mW 10 V into 600 ohms price 150 in 1960 In short the AB provides power in the audio range The CD provides a range wider than audio at less power HP held the patent for Wein bridge oscillators regulated by lamp bulbs It provided the best signal Others had to go with Twin T etc I d snap the AB on EB if was in a snapping position Date Fri 30 Aug 2002 18 14 55 0400 From Roy Morgan lt roy morgan nist gov gt Subject R 390 Manual copies HP 200CD and the older HP 200C Available Manual copies for the HP 200CD and the older HP 200C signal generators I ll be making copies for those who want them next week Date Fri 30 Aug 2002 23 54 54 0000 From Philip B Atchley lt ko6bb juno com gt Subject R 390 Millivac RF Voltmeter help have a test instrument here that I d like to get a little information on First let me mention that have used many Laboratory RF instruments during past RF careers but have never run across this particular instrument did a web search on it but all found were a couple units offered for sale with no other information suspect it is rather old as it appears to be early solid state and can hear the Choppers whine It s last inventory sticker is 1994 so suspect it was pulled out of service around that time All Know about it It is a rack mount Millivac Industries Model MV 828AR RF MilliVoltmeter with Type
166. EMENT suspect it s the TV 7 also but what s confusing is that not all tubes of a type show that short The lamp glows bright and strong on some 5814A s for example and not on others at all not even a flicker That said had posted about this same TV7 D U some months back In addition to the problem at the tube socket contacts also found that the shorts switch contacts were covered not with powdery stuff but black greasy stuff I ve seen this stuff elsewhere and think it s a type of switch lubricant they used at some time to prevent wear and intermittents cleaned it out with denatured alcohol as much as could but at the same time wasn t sure Essentially replaced it with Deoxit also trying to keep it off the ceramic It s very difficult to get at those contacts so some remaining grease may have worked its way out Now say wasn t sure about the whole thing as I ve found the same or similar grease on other switches in other equipment including contact pins in one or two Cardamatics It looked like it was supposed to be there Still not all the tubes show shorts is it a matter of degrees or rather ohms Date Sun 30 Sep 2001 21 44 17 0400 From Barry Hauser lt barry hausernet com gt Subject Re R 390 R390A tube chart amp PUZZLEMENT gt If you take a shorted tube and test it a couple of times does it always gt come up shorted I m wondering if the switch is intermittent Yes worked the s
167. General Radio stuff was big and heavy and black and was in a lot of labs but was nowhere near the high bar that the HP stuff set for equipment usable in field service And came to prefer the same HP stuff in the lab too Although do have a certain fondness for GR Hermaphoditic connectors wonder if the current president of HP appreciates that they once made stuff other than printers Date Fri 14 Jan 2011 08 45 29 0600 From Randy and Sherry Guttery lt comcents bellsouth net gt Subject Re R 390 HP And Other Signal Generators Yes indeed My EICOs came along first with a 460 scope then a 232 VTVM the 324 and a 950 Bridge which built new from a kit bought it at the Lafayette store in Hawaii Still have a couple 232s love the center meter scale for FM disc etc The 324 served for a couple decades as well until finally snagged my 606B 8640s In 1973 we the ship was on got our first 8640s hauled a couple 390s aboard to align them While great for doing the alignment hauling 390s around wasn t fun Later wound up in charge of the boat s test equipment pool and had several 8640s so just checked out one and took it home alot easier to haul around than the 390s Still the 324 would do just fine might not have been dead on and certainly a PITA to set up for sensitivity measurements etc but with care good enough to get a 390 aligned pretty well Date Fri 14 Jan 2011 11 36 55
168. Lawson lt jpl15 panix com gt Subject Re R 390 More C709 info One of my very frequently used bench instruments is a little old 50s Cornell Dubilier capacitor bridge with a tuning eye indicator Checks from a few 10s of pF to about 100 mF you know the general type It was on the FREE pile at a swapmeet some years back and it cried out to me so rescued it have several much newer more sophisticated devices to do this but for vintage test gear page 139 tube gear the little CD bridge does an easy perfect job every time and puts enough voltage accross a cap to wake it up So my oblique answer to your Question above is Ellifino wnyncha checkit an see And to do that there are a lot of older cheaper capacitance bridges and meters out there get so much use out of mine it s amazing Can t bitch over the price either Just another 200 millidollar for a Tuesday evening Date Wed 03 May 2006 07 43 37 0600 From DW Holtman lt future212 comcast net gt Subject Re R 390 More C709 info If you are thinking about using sand state AADE makes an excellent cap inductor checker It is relatively inexpensive and very precise very reliable use mine all of the time for around 3 years with no problems For testing cap breakdown use a Military AN PSM 2 A It is a Megohm meter meger It has a crank handle with two leads Hook up the cap in question and crank it shows the resistance or breakd
169. MO it needs to be set up correctly regardless of how you tune the amp when in service Date Sun 21 Feb 2010 19 15 48 0600 From Dr Gerald N Johnson lt geraldj weather net gt Subject Re Collins Interpretation of 30L 1 manual sec 4 7 The envelope is not constant at that peak value and that affects the other instruments Because with a peak reading calibrated in RMS voltmeter such as the HP410B typically specified for such a measurement will read the peak not the heating power RMS or the average And that matches the peak to peak value on the scope gt Since my scope can only handle 400 V p p eeeeeeeeeeeeeeeeees Depends A peak reading meter should show 506 watts An average reading meter will show less but think more than half Probably about 70 7 of the peak since the envelope is a sine squared waveform Date Sun 21 Feb 2010 20 57 40 0800 From Robert Jefferis lt jefferis antelecom net gt Subject Re Collins Interpretation of 30L 1 manual sec 4 7 Yes the instrument used is quite important 1 OK sure if you have one of the T coax adapters to use with the ubiquitous HP AC probe used on the 410B and 410C meters the reading is likely to be close to 159V guess this could justify the presence of the reference in the manual even if they didn t mention a peak reading RF probe connection Although believe that one of these probes will read a bit lower than 159V 2 agree a go
170. Mar 2006 12 49 35 0000 From n4bug knology net lt n4buq knology net gt Subject Re R 390 HP410B rectifier tubes It has an EA53 in it glanced at my other meter s ME 26 2 01C and it didn t appear at first glance that the 2 01C would fit in my HP 410B s probe but I ll give it a second look Maybe someone put an EA53 in this probe and I m just assuming a 2 01C won t fit It sure would be great if it does as the 2 01C is generally a less expensive tube these days Date Mon 27 Mar 2006 10 25 25 0800 From Dan Merz lt mdmerz verizon net gt Subject RE R 390 re l 177 question OT test gear page 138 Hi wonder if the same information recommends calibration of the tester when the 83 is replaced with another 83 I no longer have the one I 177 that once had but have Hickok 600 750 and TV 7 testers If can find the ss diode sub made up I ll check my three testers with an 83 ss diode substition and an ordinary 6L6 to see if there s much difference when the switch is made My 750 shows calibration sticker in 1977 by an airport agency don t think I ve ever calibrated a tube tester and don t consider it very important in the overall scheme of things The challenge of finding a reference tube for calibration is more than want to undertake unless someone has one to pass around along with the certified values Douglas provided the steps to calibrate a Hickok tester using a current source between the plate cathode
171. Mon 25 Jun 2007 19 36 18 0400 From Scott Bauer lt odyslim comcast net gt Subject Re R 390 Tube testers test gear page 147 From a maintenance point of view was told by Bill Waters The Hickok Doc that he wont even work on a TV 2 do not know why I m just quoting him Date Mon 25 Jun 2007 18 05 26 0700 From Kenneth G Gordon lt kgordon2006 verizon net gt Subject Re R 390 Tube testers TV 2 can think of several reasons 1 the early models had quite annoying problems with parasitic oscillations In my case those tend to kill A the 83 rectifier then B the 6X4s and C any VR tubes you attempt to test Later models had oodles of ferrite beads hung on practically every lead in them in an attempt to cure this problem Furthermore you can t really retrofit the ferrite beads since there are so darned many wires in there it would be easy to lose track 2 The power transformers tend to get intermittant shorts and or opens in them Replacing the power transformer is NOT for the faint of heart 3 They are AWFULLY darned big have two TV 2s an early and a later The early one has destroyed at least two sets of rectifier tubes and won t use it to test VR tubes any more watch it like a hawk when do use it The later one has a transformer fault and so far have not had the courage to attempt to fix the thing was asked once to trade an R 390 for one of my TV 2s but since could never get the lat
172. OH if it means that you ll have to replace all the crystals and find a hot tube and re bias for increased output etc etc one can reach a point of decision Date Tue 26 Nov 2002 15 34 17 0800 From Dan Merz lt djmerz 3 cities com gt Subject Re R 390 xtal wave spikes Bob the diodes in the ring detector are germanium 1N82a s so think the turn on voltage is lower if remember right compared to silicon type was down measuring some more and found lower oscill output voltages than before for some reason and thought maybe was reading my scope wrong before checked the 2nd receiver have to see if could get what measured before since had both of them on the bench when made the first set of measurements got the lower voltages there too so must have made a slip between my notes and the scale factor and the highest voltage is around 0 5 test gear page 76 volt not 1 7 And now don t see the spikes that saw before The waveforms are now very smooth I m at a loss on that I ve been passing one 6BL8 tube between the two sets for the oscill cathode follower as I m short on that tube type It may be possible that in exchanging tubes used a different 6BL8 before for the oscillators the sets have 2 each and at one point only had 2 to use between the two sets and was exchanging both now found another one and have 3 and only exchange one of them Maybe there s something in one of those 3 tubes that would ac
173. Oct 2006 18 02 31 0500 From Barry Williams lt ba williams charter net gt Subject Re R 390 Tube Tester I 177B have one too Had to look for about 3 years to find the mini tube adapter module The charts done by Nolan are first class Date Tue 31 Oct 2006 19 42 11 0500 From David Drew lt k3dxlab comcast net gt test gear page 142 Subject R 390 Re 177B Tube Tester Many thanks for all the advice received about this instrument Other than some test leads in need of replacement it is in remarkably good shape Nolan Lee s tube chart in Excel is awesome He is now my favorite redneck Nolan you are THE MAW If there were an Academy Award for Best Supporting Role in Boatanchor Maintenance Nolan would surely win a Tubie Date Wed 24 Jan 2007 21 42 06 0500 EST From Paul H Anderson lt paul pdq com gt Subject R 390 OT HP 8656A and HP 5328 timebase waveforms I m repairing a non working HP 8656A for aligning my R 390 s starting with the time base output The back panel time base output on both units are not clean sine waves Should they be perfect sine waves In fact they are quite dirty although they do have a frequency of 50MHz Date 15 Mar 2007 18 53 17 0000 From n4bug knology net lt n4buq knology net gt Subject R 390 General Radio Sweep Generator 1025A Anyone familiar with the General Radio 1025A Sweep Generator found one today in good condition but not sure if really want
174. Of course these are convertable to Hz on an even exchange basis less a 5 service charge Careful though the tz sound at the end is at the resonant frequency of some vacuum tube elements filaments and the like so repeated use of the Hz kHz and mHz words will shorten tube life gt overhauled by Tobyhana in 1983 must presume 5555 The caps were probably still good then Besides the modulator usually goes intermittent some time before it fails altogether so it probably at least mostly worked The impression one gets is the function switch is a bit dirty because if you switch it on and off modulation on the intermittent ones they often start modulating again for a while gt Man dig all that cast metal in there Yup they look good in battleship gray don t they The enemy will become hopelessly confused and flee Would go something like this I m giving the order to flee Sir don t you mean retreat No this thing they shot at us has knobs and a dial and even worse a handle on it Probably a suitcase nuke Run away Flee Gedowdahere Every man for himself Actually it may be a violation of the test gear page 334 Geneva Convention to fire de milled URM s No radium on the dials but some components may contain PCB s There ya go again Phil Always swapping away the gear No permanent relationship with the stuff more of a wham bam thank you mam thing eh That s OK means
175. One of the MTRs requirements was to lock on the top 12 inches of the Nike Hercules AND stay locked for the entire launch until intercept So such extreme measures really aren t all that necessary to perform a high degree of adjustment and tweaking of equipment That is a simple reality that some folks do not grasp despite their intellectual acumen BTW We were required to take an entire Missile battery to Ft Sill OK annually and perform actual firings against drone aircraft such as T 33 and or F 89s So know from experience the ability to achieve this level Bob NODGN gt It can be done but it is a challenge generally find that most gt hams measurements of sensitivity at HF are optimistic by 10 dB or gt more due to signal leakage For all of their good qualities R390As gt are particularly egregious offenders they leak RF like a sieve so gt ANY leakage from your sig gen will make them appear to have very high gt sensitivity gt gt Note that there are two issues signal from the generator leaking gt out of the cabinet and into the DUT and external QRM and QRN leaking gt into the DUT possibly including RF that leaks into the sig gen and gt then appears at its output jack or is induced into the cable test gear page 382 gt connecting the sig gen to the DUT gt gt It helps greatly to use a well shielded external coaxial attenuator gt e g HP355A 355B or JFW adjustable attenuators or
176. PM 5 22 00 0400 you wrote the second is a Tektronix 543A Tektronix lt grin gt gt Type 53 54C dual trace gt AN 1839A dual gt Type CA dual trace gt Type M four trace gt Type 1A1 dual trace gt Type 1A2 dual trace gt Type 1A5 dual trace The 1A2 is the best of the bunch Put your effort into it Manuals are available but tough to find at a good price DO NOT buy a photocopy of it Get an original Tektronix used light blue troubleshooting info in those old 5xx series manuals and it usually doesn t show up well if it s a photocopy Also make sure that the SN range of the manual is equal to or exceeds the SN of your 1A2 There were a hell of a lot of production changes on it have three or four of the 1A2 s and all of them are different gt The question have about the plug in s are these all usablewith the 543A I ve never seen a AN 1839A but all of the rest will work in the 530 and 540 series scopes gt others came with the 543A Except for the Type M I have no manuals for any of this stuff I ve been looking for an M manual for a while The M is OK but the usefulness of 4 traces on a 5 round CRT is questionable was playing around a while back with one of my Tek s with a total of 8 traces think it was Fun but not practical lt grin gt test gear page 8 gt which one of these plug in modules would be the most useful for working on the R388 R390 SP600 etc etc Put your effort into the 1A2 followe
177. Perry Sandeen lt sandeenpa yahoo com gt Subject R 390 HP And Other Signal Generators lt snip gt This applies to signal generators as well Some got their 8640B units from MARS and so sell them at a low price Others found a deal three years ago from a epay Dum Koff for a good working HP 8656B for 375 me paid 750 for a good used Fluke 6080 seven years ago That was a good deal Stuff at hamfests is usually less than epay unless maybe you factor in the traveling expenses All used signal generators come in varying degrees of test gear page 238 condition original features price availability personal preferences buttons or knobs and the serendipity factor of luck The got the whizbang for peanuts story We look for the best price performance ratio that our budgets and personal situations allow There is no gold standard that any of us can afford So we get what we can get at that moment in time A reasonably working of the afore mentioned generators are far better than a URM 25 or a HP 606 IMUHO Date Thu 13 Jan 2011 21 00 46 0800 PST From Drew P lt drewrailleur807 yahoo com gt Subject Re R 390 HP And Other Signal Generators I like my EICO 324 grin Date Fri 14 Jan 2011 01 25 44 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP And Other Signal Generators Many of us started with a 324 that was the first generator owned or a Heathkit SG 8 LG 1 or RF 1U in my view
178. R 390 TEST EQUIPMENT RECOMMENDATION would appreciate knowing what The List Recommends in order to do a good an accurate job of electrical restoration and maintenence Not physical restoration My collection includes an R 390A a dozen pieces of Collins S Line test gear page 168 and some E F Johnson probably have little more test equipment than what the average Ham has good VOM VTVM Scope and a few pieces of HeathKit Since am only working on my own equipment don t want to move to the level of A Service Monitor etc Perhaps the Tube Type would be best as could fix it if it breaks Models and Manufacturer would be great All recommendations graciously accepted Date Fri 25 Jan 2008 18 44 57 0500 From Harold Hairston lt k4hca alltel net gt Subject R 390 Re Collins TEST EQUIPMENT RECOMMENDATION forgot do have a TV 7 Date Fri 25 Jan 2008 18 50 17 0500 From Jon Schlegel lt ews265 rochester rr com gt Subject Re R 390 TEST EQUIPMENT RECOMMENDATION guess the next item I d add would be a signal generator For general receiver work you really need a generator that s stable RF tight and with a correctly operating attenuator There is nothing more perturbing than setting the attenuator to max and having the receiver under test still responding to the generator signal due to the RF it is spraying or leaking around the attenuator My personal favorite sig gen is the HP 8640B but it s not vacuum tube a
179. R 390 Tube testers My experience with the my first R 390A with tubes and testing has been a combination of both approaches V204 a 6C4WA tested very bad on my Hickock 600A did not replace any of the tubes after testing During sensitivity test gear page 264 improvement testing V204 was replaced which resulted in a 10db improvement V501 a 5654 6BA6 had tested good but when replaced resulted in about a 3dbv improvement V506 a 5814 had tested good resulted in the diode load voltage increasing by about 30 and a slight decrease in sensitivity The original tube was used During my days in the RCAF as a heavy Radar Tech tube testers were seldom used For routine problems like low MDS the only reliable and efficient way to correct this problem was tube replacing For the occasional difficult problem tube testers were used to give an indication of where the problem was tube or other component BTW tube replacement was real pain with those amp stuck IERC tube shields Enough of the Bull for now Date Fri 2 Feb 2001 12 07 11 0500 From rbussier lexmark com Subject Re R 390 Tube testers agree that the best tube test is use in the device under discussion It is more useful in receivers however Swapping tubes in a cap tester or other piece of test gear may not show you anything meaningful bought a tube tester because it allows me to cull the duds from some lots have obtained You can find some great buys if you look
180. R 390 tube testers amp meters gt It s still pretty rough The I 177 meters are out there picked gt up a NOS spare Simpson one last year for ten dollars as part of a gt deal on some other stuff A few weeks later watched Surplus Al gt sell one on ebay for about fifteen or twenty dollars Still not a bad deal Yep that is a good deal forgot how came about my replacement meter Somebody had one they were willing to part with found this guy through some hurried bumbling around on the net Then someone else asked for my old one and had a really good reason to want it so sent it off to him Wish had kept it but he needed it and I m not selfish gt The early meters like the I 177 Simpson are held together with three screws My replacement is the Simpson 3 screw type Glad to find that this morning when read your mail and went to check think the old one was the sealed meter remember looking at it and thinking that a hammer was called for if was going to open the thing up It sure did flash nicely though when burnt it up gt Which model tester and meter Supreme I 177B with a serial number of 833 Order No 2960 P 52 04 finally found the MX 949A U last year after 3 years of searching It is stamped as Order No 3029 Ph 61 paid too much for the adapter but after looking all over the place was ready to just buy the thing and be done with looking think that they will remain next to impo
181. Subject Re R 390 HP 8640B vs HP 8654A 8655A 11710B Okay Don l m just doing simple IF RF alignment so guess it s probably good enough for my purposes The 8655A is the counter and not sure how much extra noise it would add to the mix Still might just go with an 8640B The 11710Bs cost almost as much as a good 8640B Date Sun 9 Jan 2011 22 28 37 0600 test gear page 230 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 HP 8640B vs HP 8654A 8655A 11710B Make sure the 8640B has a fully operating gear train The plastic gears are a weak spot in these generators l m not aware of spares either One that works is a nice machine have one and a 606A Date Sun 09 Jan 2011 23 41 58 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP 8640B vs HP 8654A 8655A 11710B gt The 11710Bs cost almost as much as a good 8640B Timing bought several for less than 100 each a year or so ago from a guy who had a pile of NIB ones on eBay They appeared to be selling well he upped the BIN price after a while guess he must have run out see there are a number of 8655As for sale so they must not have been as rare as remember them being But the asking prices are more than I d pay for an 8640B So if you sell your 8654A and 8655A you may well have enough to buy a nice 8640B Date Sun 9 Jan 2011 21 46 12 0700 GMT 07 00 From Richard W Solomon lt w1ksz earthlink net gt
182. Subject Re R 390 TV 7 lid gasket was going to suggest you go to a good NAPA Auto parts store they sell all kinds of this type of door and window seal material by the foot Date Thu 7 Jul 2011 12 47 53 0500 From Dave Faria lt Dave_Faria hotmail com gt Subject R 390 TV 10 Lid Gasket If all else fails use some cold weather pipe wrap Home Depot sells it in 20ft rolls for maybe 5 It is a tough foam rubber and sticky on one side The rubber is abt 1 8in thick and 1 5 to 1 75 inches wide Easily cut with a pair of scissors Date Thu 7 Jul 2011 20 05 01 0400 From Barry lt n4buq knology net gt Subject Re R 390 TV 10 Lid Gasket Would this type of gasket material work http www tubesandmore com scripts foxweb dll moreinfo d dfs elevclients c emirror ELEVATOR FXP item P D280 Date Thu 7 Jul 2011 20 11 36 0400 test gear page 376 From Barry lt n4buq knology net gt Subject Re R 390 TV 10 Lid Gasket Also have you checked McMaster www mcmaster com for rubber gasket They have lots of different forms Date Thu 7 Jul 2011 18 56 48 0700 From Foster lt Fosterp pahrump com gt Subject Re R 390 TV 10 Lid Gasket Has anyone asked the TV 7 GURU Dan Nelson about the gasket materiel for the TV 7 series cover He was advertising in Electric Radio 73 Foster W4HCX Date Thu 7 Jul 2011 21 16 43 0700 From Foster lt Fosterp pahrump com gt Subject R 390 FW TV 10 Lid Gasket Follow
183. Subject Re R 390 Tube testers went through the same problems with my first R 390A over the past 7 months got lucky last fall and picked up a Hickok Model 600A less cover at a local ham fest for 20 00 CDN here in Montreal The fair market value should be about 125CDN Cleaned it up a bit made some adjustments and now it works fine Compared performance with a friends TV 7 with good results The Model is not the best Hickok but for my purposes is good enough For prices used e Bay as a baseline for cost high end price and max to pay See this WWW site it s the best you will find on Hickok tube testers http www Owned org hstraub hickok htm Date Fri 02 Feb 2001 09 44 23 0600 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 Tube testers The very best tube tester for your tubes is the radio itself No kidding Date Fri 2 Feb 2001 07 03 34 0800 From keith lt khgrant ix netcom com gt Subject Re R 390 Tube testers Thanks for everyones response I ll try some tube swapping in the rig I m also going to keep my eye out for a tube tester It appears that TV 7 s are pretty common Can someone summarize the differences between the different models in the TV series Do any of them have transconductance I ve heard of TV 2 s and TV 10 s as well I m not looking for a collectors item just a good quality box Date Fri 02 Feb 2001 10 51 05 0500 From Al Solway lt beral videotron ca gt Subject Re
184. WII stuff I ve had my old RBC 2 since was a teenager I ve been looking for an RBB series that was local for ages They re too big and heavy to ship I m still looking for a couple of little doodads to complete my RBC 2 like two of the little metal dial glass retainers one of the red fuse holder caps for the power supply a voltmeter a couple of knobs and a few other little doodads could use one more of the old concentric coax connectors too don t know what happened to all of them They were common as hell 25 years ago gt Dallas mentions that the Vitamin Q types do not normally require replacing Why not since they are also paper Do they go bad in the390xx The old Vitamin Q s were probably some of the best constructed paper caps made Oil filled and heramically sealed with glass and metal Of all of the caps that I ve removed from the various R390A s and modules they failed the leakage test the least often I d still replace all of them in the receiver while you re in there Cheap insurance over the long haul When did the audio deck on the EAC used some NOS Vitamin Q s that I d been saving for some of the locations on the circuit board where didn t like the way that the orange drops fit tested the hell out of them a little over their rated voltage and they were perfect even left them at full operating voltage on one of the PS s for a couple of days and then retested them guess that they aged well The only
185. Zion Street Frederick MD 21703 5932 Date Fri 15 Sep 2006 14 42 06 0400 From David C Hallam lt dhallam rapidsys com gt Subject RE R 390 IF Deck Revisited Revisited For anyone who is having trouble finding 410B or 410C probe points they are readily available if you look for steel phonograph needles You might try restoration resources for old radios etc There are a number of sellers on eBay found a package of them at a flea market Date Fri 20 Oct 2006 14 21 57 0400 From K3DX lt K3DXlab comcast net gt Subject R 390 Tube Tester I 177B I ve just acquired a Dynamic Mutual Conductance tube tester I 177B with the socket adapter kit MX949A U Before power up this puppy and risk letting all the smoke out are there any precautions should take The line cord has been replaced with a 3 prong version The cord insulation looks good l Il open it tonight and look for leaking cracked caps and cracked resistors The circuit is fairly simple isn t it Does it even use DC I m impressed by the meter It has three scales in microMhos That seems a lot better than good OK bad From what see in the charts almost all the R390A tubes require using the adapter octopus The charts are dated 1952 as is the socket adapter kit Date Fri 20 Oct 2006 14 12 32 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 Tube Tester I 177B http www acadiacom net nlee Here ya go Bubba Date Fri 20
186. a 455 000 kHz Xtal use such a test jig for determining the center frequency of the series resonance and the Q of crystals that might use for ladder filters built it with a connector that goes direct to the BNC on my scope input to give it an anchor use a different test oscillator for testing crystals for oscillation its faster than dialing up a series resonance copied the oscillator circuit from the Collins 821A 1 250KW transmitter and included what turned out to be a diode multiplier With a 100 pf variable in series with the crystal can move the parallel resonant operation around quite a bit It has good output at 2m which was its original intent Its built in a 4x6x2 bud box with cover and the round 9 volt transistor battery lasts decades do have a circuit of it here in a booklet that put out for a radio club program so could scan and e mail it if desired It runs overtone crystals on their fundamental because the oscillator is not tuned test gear page 295 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 Signal generator connection questions Works great to identify the SERIES resonance of the crystal That may be the calibrated frequency but most crystals below 20 MHz are calibrated at a parallel resonance with 20 to 32 pf in parallel with the crystal So the series resonance found this way is NOT NECESSARILY the marked frequency There can be as much a 2 KHz difference be
187. a ath cx gt Subject Re R 390 test equipment question True And it provides such a sense of satisfaction once one gets over the initial rage grief and despair and into the steely eyed mood of absolute This WILL Happen determination haven t yet had to descend to making my own Allen wrenches but have more than once made a screwdriver of the right size suppose could in principle at least make a soldering iron but really hope to avoid that extremity Date Fri 13 Feb 2009 12 20 08 0500 From David Goncalves lt davegoncalves gmail com gt Subject Re R 390 test equipment question Common comments from system andministrators Coincidence This hardware engineer says no uncalibrated test equipment shall pass through this threshold let the vintage radios do the smoking Date Fri 13 Feb 2009 12 21 16 0500 From David Goncalves lt davegoncalves gmail com gt test gear page 178 Subject Re R 390 test equipment question But do have a Measurements Model 80 signal generator in the shop that restored Date Fri 13 Feb 2009 09 43 09 0800 PST From wli lt wli98122 yahoo com gt Subject R 390 R 390 Test Equipment Question You have all you really need EXCEPT for the all important Bristo wrench set Get them from McMaster For alignment all that is needed is an AC voltmeter with a dB scale a 600 ohm resistor and a URM type RF generator The AN PSM 4 was called for in voltage and resistan
188. a good choice leakage phase noise stability etc Date Thu 10 Feb 2011 18 15 04 0600 From KAQEGW lt ka9egw britewerkz com gt Subject R 390 8640B new toy here Got a new generator for the bench an 8640B with option 004 the 1dB step attenuator I d like to add option 001 the continuously variable audio oscillator to it and understand option 001 is retrofittable but as yet have no clue where to go for parts or documentation Even without option 001 it s still a very nice tool test gear page 242 Date Thu 10 Feb 2011 20 46 28 0500 From Barry lt n4buq knology net gt Subject Re R 390 8640B new toy here got my first HP 8640B last week It has Option 3 I ve done a small amount of fixing to it but nothing very major I m lovin it Date Thu 10 Feb 2011 23 03 36 0500 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 8640B new toy here Is Option 3 the frequency doubler extending the range to about 1 kmc kHz The 8640 have here does not work on FM If anyone has a spare FM board might be able to buy it and fix my generator Date Fri 11 Feb 2011 09 18 06 0500 From Barry lt n4buq knology net gt Subject Re R 390 8640B new toy here Option 3 is Reverse Power Protection Mine came with one of the cards necessary for the frequency doubler but there is additional circuitry required to make that option fully functional The gears in mine are cracked but not separat
189. a lot more often from RF or DC overload The test gear page 354 gt thing that usually goes is the part would be a resistor to ground in a PI pad gt gt If you want to go whole hog on your new pad you can put a small DC gt voltage on the input and check the DC on the output The key issue here is gt keeping the DC low enough that you don t blow up the pad Depending on gt your voltmeter you can check pads up into the 30 db range this way Past gt that an AC signal and an AC voltmeter probably are a better idea gt gt Both of these techniques depend on the fact that the DC and RF performance gt of the pads are nearly identical This is normally a good bet at R390 gt frequencies It may not be as good a bet at microwaves have certainly gt seen a number of dummy loads that are AC coupled have not seen any wide gt band attenuators that are AC blocked though Bob Camp Date Sat 9 Jul 2005 12 24 07 0700 From Craig C Heaton lt wd8kdg worldnet att net gt Subject R 390 R 390A test equipment Had to relate this to a R 390 or R 390A somehow Has anyone on the list recapped an URM 25D Did you test any of the old caps to be able to recommend which ones are most prone to fail have an URM 25D to align my R 390A and its starting to act a little strange after warming up Did take the time to test the caps in the power supply and they were fine Although did think it was strange the filter caps were paper and not elect
190. a lot of tubes Is anybody interested in a gizmo like this If there is then it s probably worth figuring out how to do it A lot of us already have tube testers so it may not be worth doing test gear page 109 This would be strictly a here s the schematic go to it type of thing have no intention of trying to sell them or build them All the wiring would be point to point stuff The parts except for the tube sockets would all be Radio Shack type stuff The tester should be a reasonable weekend project with plenty of time taken off necessary distractions like using radios If you are interested let me know The only thing need to know is whether you already have a voltmeter current meter If so what is the lowest current range it will show The gizmo can be designed for a plug in meter or a built in The design will be a little different depending on which way we go Parts list more or less one 9 pin tube socket two 7 pin tube sockets two 6 volt filament transformers one push button one dpdt switch one 1N4007 diode 3 60 01 uf caps some number of resistors a power cord fuse and on off switch Depending on the voting either a couple of pin jacks or a meter Date Mon 25 Oct 2004 21 21 25 0500 CDT From jnhaynes earthlink net Subject R 390 Tube tester have a friend with a couple of tube testers for sale mentioned it on several mailing lists maybe not here and he has got hardly a nibble of interes
191. about 18 pages if remember correctly Dallas has not made a similar set of notes for the F model unfortunately The original cost of these notes was VERY modest and no URM 25D owner should be without one Additional articles about the URM 25 are HSN Issue 34 Winter 1994 95 Short Subjects Balky Modulation Oscillator in the URM 25 by Allan Douglas about the R C T network and padding a capacitor to make it work again HSN Issue 41 Spring 1997 URM 25D Rebuild Notes Supplement a drawing of the Terminal Board Courtesy of Ray Mote this issue also includes Captain Lee s Product Detector for the R 390 R 390A Revisited Part 2 SSB Adapter Revisited see HSN 10 for Lankfords initial report bridge rectifier and 6Uf capacitor only found inside Date Mon 14 Nov 2005 13 57 05 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 R390A URM25 gt Could anyone please let me know the differences between the URM 25D and gt URM 25E Signal Generator models Anything significant test gear page 356 Robert am not all that sure but think that the E model was a different contract and the basic signal generator was very similar if not the same The F model however IS different It uses the same basic circuit but the mechanical arrangements and construction are different Date Mon 14 Nov 2005 18 57 27 EST From Flowertime01 wmconnect com Subject Re R 390 R390A URM25 Not really
192. ack If you don t want to spend the prevailing prices on TV 7 s TV 2 s TV 3 s the better Hickoks you can find a usable less popular sleeper like a Precision 10 12 or 6 something which have some support on the net There are a number of B amp K s that are good and even an RCA version of the Cardamatic All can be had for under 100 Tube testers can be fun too You look up the settings in fine print in a book or roll chart extra fun then set all the switches bias or shunt and check em twice Plug in the tube and wait a few seconds for the glow step through the shorts test Good OK then the moment of truth the quality test If you ve got the time the gas test too Be sure to tap the tube on the shorts test H ray we have a winner Sometimes it s even more fun than playin the radios hollow state in its essence PS with this post may have driven the price of tube testers up another 20 Arghh Date Fri 2 Feb 2001 07 08 38 EST From G4GJL aol com Subject Re R 390 Tube testers agree Barry Good Point stand by my post regarding a set which hears noises but doesnt perform to spec BTW My collection of boxed control tubes on the shelf made it through a tube tester check a few years ago do actually have and occasionally use a NATO spec Mullard manufactured CT160 Tester Valves Electronic test gear page 263 Date Fri 02 Feb 2001 09 36 17 0500 From Al Solway lt beral videotron ca gt
193. ads can load the grid circuit of an R 390 or R 390A with respect to RF or IF signals there The mixer grids have the local oscillator signal present If that signal gets sucked out by the capacitance of the meter the results will be confusing at the least It isn t the buffering of the meter that matters when measuring oscillator or mixer grids but the isolation provided to the circuit under test Certainly the VOM s common in the time of the R 390A would cause trouble measuring some points in them lt Roy on Soap Box OFF gt test gear page 174 Date Fri 13 Feb 2009 00 28 15 0800 PST From Steve Toth lt stoth47 yahoo com gt Subject R 390 test equipment question Some questions for the veteran radio techs I m organizing to start work on a couple of R 390A s just acquired What test equipment do need as opposed to would like to have to get these babies running What have now TV 7 U tube checker and spare tubes AN URM 25D signal Generator Heathkit VTVM Digital VOM Digital Dial Direct Freq Meter good to 50Mhz Looking at the Y2K manual pg 1 12 and looking thru the stage by stage troubleshooting steps in Section 5 three other items are mentioned 1 RF Multimeter can use an adapter with the VTVM or VOM How 2 Audio Oscillator that covers 425 3500hz 100mv 3 Oscilloscope that can cover 2 to 2vdc cm If do need em what inexpensive models should look for at ham flea markets got a big one comi
194. advance to everybody Date Wed 02 Dec 2009 17 58 13 0100 From Heinz Breuer DH2FA lt dh2fa darc de gt Subject Re R 390 HP 410C Original manual Be careful when buying a HP 410 C manual The HP 410C was built over a twenty year period and changed from a tube to solid state There are at least 3 different schematics Be sure to get a manual that matches your serial number prefix test gear page 211 Date Wed 02 Dec 2009 17 21 55 0600 From Robert Nickels lt ranickel comcast net gt Subject Re R 390 HP 410C Original manual Heinz advice is sound I ve found major differences that aren t reflected in the manual backdating change sheets I d suggest that you get your serial number and then compare with the copies at http www hparchive com hp_equipment htm But check the backdating details in Appendix C rather than relying on the cover sheet which for my s n block was never updated Date Mon 11 Jan 2010 10 16 39 0500 From Barry lt n4buq knology net gt Subject R 390 OT Wavetek function generators Looking for comments on Wavetek function generators Are they a relatevely good build quality etc Local fellow has an older one just a generator not a sweeper similar in build to the following http www testelectronics com used wavetek114 htm IIRC the one he has is good through 100kc bought another generator a few months ago but not really impressed with it and am looking for another that might be a be
195. al pins to look nice Solder the pig tail wires in the octal socket pins and trim Bob Camp wrote a good procedure to adopt any tube to any tube tester Many tubes were missed in many tube tester lists Watch the TV7 knobs as you set it up for a known tube You see that a couple switches set the filament pins One sets the cathode one sets the plate And so on down the line of switch settings The same knob has the same function on every tube Some other tube testers are pin to function dependent The switch serves the same pin every time and selects fil cath plate open The bias selects a grid bias There are other setup do not remember off the top of my head Do a bit of study and your tube tester becomes a lot more useful Adapters can be made switch setting divined bias values fathomed and meter values established Tube testers are just another item of test equipment and new ways to apply them can be discovered all the time Some think tube testers just make good foot test gear page 167 rest poor door stops or paper weights Others find all kinds of ways to apply the test instrument in creative ways and gain meaningful test results from the experiment of the moment Date Thu 24 Jan 2008 20 50 23 0600 From Barry lt n4buq knology net gt Subject R 390 FA GR Audio Meter Some of you guys might be interested in an audio power meter for measuring output on the R390A etc sold my TS 585 but this thing sure looks
196. ale SG 1144 U Sig Gen Solid state successor to the AN URM 25 series A manual for this puppy can be found at the ETM site http www logsa army mil etms find_etm cfm From Jerry Kincade lt w5kp direcway com gt Date Sun 19 Jan 2003 17 07 57 0600 Subject R 390 SG 1144 U sig gen is sold test gear page 342 The sig gen is sold Thanks for all the interest wish had enough of these to go around I m a bit surprised haven t heard them mentioned on the list All hear about are AN URM 25 s but there must be a zillion of these 1144 s out there somewhere I ve used both and IMHO this is hands down a nicer generator to work with Maybe it s because it only has a four digit freq counter but that s four more than the 25 s have 73 Jerry W5KP From Bryan Stephens lt mail08458 pop net gt To R 390 List lt r 390 mailman qth net gt Subject Re R 390 URM 25D Signal Generator Date Sun 7 Dec 2003 11 51 48 0500 IIRC there is a URM 25D manual available for download on the K4XL s BAMA site http bama sbc edu However if anyone needs a hardcopy of the full URM 25D manual theory operation maintenance parts still have a batch of very high quality reprints hi res scan from my original w clear photos 11x17 schematic 24lb paper 67lb covers for 6 ea postage If interested please contact me directly obryanste yahoo com Bryan Stephens bryanste yahoo com KG4UPR Potomac Falls VA Date Sun 7
197. ame Date Tue 8 Apr 2003 22 20 27 0700 PDT From John Kolb lt jlkolo cts com gt Subject Re R 390 Suggested Test Equipment for R 390A Alignment Most any signal generator that covers the required frequencies will do for an alignment To measure the receiver sensitivity requires a well shielded unit with a good attenuator The Heathkit lab grade signal generator need not apply here URM 25 s were the standard Navy signal generator during the era of the 390 s so are in the offical proceedure but not required They were widely available surplus and cheap so became popular with the radio hobbyist Best generator here is a Logimetrics picked up at the swap meet for 20 a few bad spots on the output attenuator but easy to use an external attenuator instead Anyone interested in a HP 606A for 50 Pickup only near San Diego Date Fri 09 May 2003 11 19 08 0400 test gear page 82 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 OT CHEAP DVM S The original poster mis spelled the maker of the thing It is Cen Tech not Gen Tech I think found it yesterday but today the search function is not working If you can get a listing of meters then find the more expensive meter by the same company to confirm the spelling the cheap meter is not listed if you search for meter or 7 function Then search on the correct maker s name once the search engine is running again There seems to be no good catalog b
198. ams lt jupete bigpond net au gt Subject R 390 Sweep generator wanted G day USA wanted is a HP 8601A sweep generator got some Racal needing a check over for one thing Yep been to the bay but never found the water cool enough Any lying around superflous to requirements Date Sat 26 Jan 2008 21 11 30 0600 From mikea lt mikea mikea ath cx gt Subject Re R 390 Sweep generator wanted I ve got a dodge for you if you ve got an HP 8640B or other generator that does DC input FM and you have or can build a linear ramp generator run the output of the ramp generator DC coupled into the FM mod in jack of the 8640B set the unmodulated freq for the low end of the sweep range for a going ramp starting at OV and then set the modulation gain pot on the 8640B so that the high end of the sweep is to or past the range you need swept also use the ramp as x axis drive on my scope so that see the output from the DUT as a true response curve It works a treat My 8640B goes down to about 450 KHz which is good for most IFs and up to about 1 2 GHz which is a bit better than the 110 MHz of the 8601A Ramp generator schematics are available on the web though use my sweep generator s ramp output which test gear page 171 is fudging admit but it still works Just in case you can get an 8640B and not an 8601A Date Sun 23 Mar 2008 20 53 40 0600 From Sam Letzring lt sletz msn com gt Subject R 390 hp
199. an 2011 20 11 44 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP 8640B vs HP 8654A 8655A 11710B Well the 8654 A or B was never intended to be an 8640B class generator In terms of signal purity it may be the dirtiest RF generator HP ever made including the earliest synthesized models Fine for basic alignment but not really useful for twin tone IM measurements or anything fancier These days one would typically use it with a counter but be careful the auxiliary output on the rear panel is not well isolated and any crap that comes out the counter s input not at all unusual can end up on the main output further compromising signal purity suggest using a 20 dB pad between the rear panel output and any counter to minimize this The 11710B works reasonably well use them with 8640Bs to get below 400 kHz but the internal crystal oscillators are a bit noisy so the mixed output has a poorer noise floor than the 8640B and also has more phase noise if you are doing anything where phase noise is a concern As Al noted the B version makes a voltage control input available on the back panel If you have the HP 8655A reference phase detector or build something similar the originals were rare even in their own day you can use this input to lock the 8654B to an external standard at the price of quantized frequency steps Date Sun 9 Jan 2011 22 21 38 0500 From Barry lt n4buq knology net gt
200. an it looks at first Often they are set up to do a measurement that is affected by the DC current through the tube A tube with high DC leakage will pass the test on a tester set up this way You can only do just so much with a simple tester Date Wed 27 Oct 2004 08 19 07 0400 From Gord Hayward lt ghayward uoguelph ca gt Subject R 390 Tube testers agree in part The tube tester didn t catch the small filament cathode leakage that plagued my noise limiter That being said get a lot of tubes at flea markets and the tester lets me cull the duds Emission testers get some but then acquired a transconductance tester and the end results got a lot better Everything has its place Date Wed 27 Oct 2004 20 53 06 0400 From Michael Murphy lt mjmurphy45 comcast net gt Subject Re R 390 RE tube testers We are not that interested in DC gain or even DC Transconductance think Let s talk AC and High frequency There probably are only four tube types in the 390 worth testing if you are talking about sensitivity and signal handling which seem to be the hot buttons think these could be handled with a high frequency bench generator at say 500 kHz and 10 MHz a chassis with wired tube sockets and a high gain low noise amplifier and finally a Scope or high frequency AC meter to test high frequency gain and noise This would not be the simplest way to find Good or Bad tubes but it would be a possible way to find Better tu
201. and retain period pieces other than a few pure collectors The TV 10 is just fine However l Il stick with the later WE labeled Hickok LS 1XXXXxX series It adjusts to the line voltage and reads directly in mhos There is one flaw in blasting crud off tube elements by heavy current blasts The one element that may need this is the filament This would occur in thoriated tungsten filaments It would be prudent to keep this blast per se down to a certain percentage above the normal operating curve The key being current in lieu of voltage The element will only take a certain amount of current as its resistance is essentially fixed Yes there is some degree of variation depending on whom made the tube but it is just like testing a fuse with an over current These aren t circuit breakers One blown the method of repair becomes solely replacement The older some of the tubes are and how much the audio crowd has latched upon them determines how much this replacement is going to cost you Date Mon 06 Aug 2012 14 11 17 0500 From Randy and Sherry Guttery lt comcents bellsouth net gt Subject Re R 390 Testing tubes r392 Why any competent technician would only resort to such on tube that is otherwise useless if it gets another few hours out of an otherwise worthless tube how is that bad bad idea Surely you re smart enough to know better than blasting a good tube mean what would be the point Sheesh Date Mon
202. and the PTO as straight and spread from 3 455 to 2 455 as you can manage These two events are a once only alignment Once the BFO gets set to 455 scribe a mark on the shaft at the chassis If you ever lift the chassis then mark where the shaft couples to the inductor inside the IF chassis You will find your PTO band spread the first time test gear page 30 you do a zero calibration and role the KHZ know from end to end If its less than 5KHz just leave it alone until you can borrow a frequency counter for an after noon Again once you get the PTO spread down to 10 HZ or so and flat as you have the time and persistence to work it then it will not need attention again until it grow a 1000 cycles off on the spread and is usable very good usable out to 5000 cycles If you change the 5749 in the PTO you may have to change the PTO to KC shaft adjustment to get the dial over run centered again A tube change will not be a reason to do a diligent realignment of the PTO internals PTO s can would go years without needing alignment Do not worry about the brand name on your signal generator or its model number have done alignments against stations near the alignment points on field equipment After a ride over land things would bounce around We would just tweak a loose slug back right in the rack The thing that will get you the most out of your receiver is to practice practice practice The second thing that will improve sensitive is tubes Not new tu
203. ank Date Mon 19 Jul 1999 08 18 18 0700 From dma islandnet com Subject Re R 390 Tek scope 502A If Nolan can t find his manual let me know and if you still need the specs can copy a few pages of the manual for you Jan test gear page 3 Date Mon 19 Jul 1999 03 15 38 0500 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Tek scope 502A Traffic has been low Well up until triggered a near riot that is It s a true dual beam with a bandwidth of about 1 Mhz if remember right Email me back with the exact model number and if it s a rack mount model or not and the serial number of the scope owned a few of 502 s and 502A s and probably still have an original manual in the correct SN range that I ll make you a good deal on Photocopies of the old Tek scope manuals usually suck on account of a lot of the test measurement values being printed in them in light blue which doesn t copy worth a damn Date Mon 19 Jul 1999 10 25 41 0400 From Christian Fandt lt cfandt netsync net gt Subject Re R 390 Tek scope 502A Yes about 1 MHz for sure Nolan means that there are actually two electron guns in the CRT thus making it a true dual beam as opposed to the typical dual beamers which simply alternate which of the two input channels are sent to the single gun CRT Great for catching short duration events which could be distorted or even hidden by the switching action gt gt before lash out for
204. ap for the band I m working on 530kc to 1800kc is close to mid point about halfway meshed so that s a good thing just don t know what to do to make this thing linear again tried changing the position of the dial for test gear page 203 this band by resetting the endpoints up or down 50kc In other words 530kc to 1800kc became 500kc to 1730kc This way 1000kc was really 930kc etc but the problem didn t improve tried going the other way 580kc to 1850kc with similar results was told there is a sweet spot where the dial plate could be repositioned and it might correct this problem but rather than move the dial physically moving the endpoints like this is effectively the same thing had thought about bending the fins on both ends of the capacitors thus reducing the capacitance at both end points and effectively increasing the capacitance near the middle but this seems a bit of a far out method Are there other things that might effect this Maybe someone on the list has had a similar problem with a 606A and could give me some Pearls of Wisdom Date Tue 21 Jul 2009 01 01 20 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 OT Problem with HP 606A linearity You are correct the shape of the cap fins was selected to give approximate linearity Typically the outer fins are segmented radially so they can be adjusted segment by segment for closer tracking Reducing the spacing increases the capacita
205. ape tried the sticky portion of a post it with some scucess but like ur tape suggestion too What kind of probe do u use to manipulate the spring Date Sun 15 Jun 2003 17 41 55 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 Meter Meister test gear page 89 Update so far This meter is in a 5 3 4 square copper plated steel box painted black 3 1 4 deep the mirrored meter is 5 wide and 2 3 8 high the coil is HUGE by most meter standards 1 1 8 X 1 3 8 the moving coil is inside an aluminum doughnut There are no protecting diodes of any kind just two coils evidently series resistors BTW there are three tiny balancing nuts on the needle placed at 90 degrees apart from the needle itself Mostly it s a bare meter movement have a similar DC current meter to pair with it if can keep it working The needle is free responds to full scale with the puff test smoothly too It s not however my biggest meter that s a Welch that s 14 X 14 YES the ones you saw in high school science class The Steel Six came from the USAF and is due to be calibrated again in 2006 That s why this is such a bugger Anyway the meter glass had been replaced before got it because it was plexiglas just put in a new piece of REAL glass no telling what went in there over its life time but it is dusty in there Thanks good suggestions Date Sun 15 Jun 2003 21 59 42 0400 From Barry Hauser lt barry h
206. ariety of Leader test gear including a scope and various signal generators The stuff isn t H P or Tek but it always did what it was supposed to do and reliability was never an issue still have a Leader transistor curve tracer which haven t used in quite a while but it works pretty well too Date Sat 21 Feb 2009 18 40 37 0600 From Barry lt n4buq knology net gt Subject Re R 390 Leader Equipment Thanks for all the input guys had an HP 200CD and liked it but sold it a year or two ago was thinking of getting more test gear and thought I d go for an audio generator a little less bulky etc saw a hand held jobbie on eBay that looked kind of cool but more than want to spend for one Date Sat 21 Feb 2009 21 00 33 0500 From bill riches lt bill riches verizon net gt Subject Re R 390 Leader Equipment Yes An oldie but goodie Date Sat 21 Feb 2009 21 59 32 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 Leader Equipment Leader made a wide variety of items of differing quality over the years Based on what they made in the 70s always thought of them as kind of like B amp K not Bruel amp Kjaer B amp K In the 80s and 90s Leader tried with limited success as far as could tell to move upmarket with a line of microprocessor controlled equipment lots of buttons no dials have a Leader 1300S 2 MHz analog sweep function generator that works OK think those
207. around Every piece of tube gear obtain gets all the tubes tested during the cosmetic restoration The ones that are open shorted or otherwise nfg are pitched do this on tubes receive from RF Parts AES etc When the spares are about to go back into the device they make another trip through the tube tester and then into the device Because of the close confines in some of our beloved BAs its not a whole lotta fun or is it naw it s not to swap a dud into place Although tubes are still fairly cheap you can buy older pieces of test equipment loaded with them for next to nothing Date Fri 2 Feb 2001 14 13 23 0500 EST From Norman Ryan lt nryan duke edu gt Subject Re R 390 Tube testers TV 7 D is a handy size and more than adequate for most purposes like using mine Prices are getting a bit out of hand though Date Fri 02 Feb 2001 14 40 23 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Tube testers I m pretty well fixed as far as tube testers so have to disagree with you on that sorry gt Use well worn tubes in the PTO BFO and RF stages test gear page 265 Aged but still pretty hot tubes are a good idea for the BFO and VFO yes never install new tubes in these locations have to disagree about the RF stages though There s nothing like a new hot 6DC6 in the R 390A Ditto for the 6BZ6 and 6AN5 in the R 1051 series gt Then juggle what remains in the IF to get the
208. as good enough It reads about 3 low at 12 khz and close on up to 7 khz Thanks for any thoughts on my question best regards Dan Date Mon 12 Jul 2004 21 00 40 0700 From Dan Merz lt djmerz 3 cities com gt Subject Re R 390 DMM bounce Hi Bob ok that helps wondered if the autoranging process did what you mentioned and didn t allow the current thru the inductance to settle enough before the next range check never ran into this before with my meter which isn t autoranging And the other guy evidently hasn t run into it with his autoranging meter either but this particular transformer has a high permeability nickel core that contributes to the high inductance compared to most audio transformers that I ve run across Most of them have about 5 10 or maybe 20 H primary with corresponding 45 90 and 180 H secondaries based on typical 3 1 winding ratio I m kicking myself for not suggesting that he try an old style ohmmeter before sending the thing back to me thanks for the response best regards Dan Date Wed 14 Jul 2004 16 29 52 0700 From Dan Merz lt djmerz 3 cities com gt Subject Re R 390 DMM bounce Hi Joe and others confirmed that the problem was due to autoranging bounce combined with the high inductance of the secondary of the transformer There s too much inductance for the meter to settle down and make a reading of resistance confirmed this with a small pocket RS multimeter that has only autoranging On th
209. as outlined to us how to grade performance in each location in a R390A It may sound tedious but IMHO it is time well spent if you want to optimize performance Took me a long time to finally achieve that magic 30 1 ratio in the IF audio circuitry Date Sat 8 Nov 2014 12 59 31 0800 From Perry Sandeen via R 390 lt r 390 mailman qth net gt Subject R 390 HP 3586B Info test gear page 412 I ve assembled three PDF documents for the HP 3586B An electrolytic capacitor replacement list a 15 KHz IF pick off doc and the Beethoven audio test You get three for the price of one FREE If interested please send me a new email off list Date Sat 8 Nov 2014 17 52 31 0500 From Frank Hughes lt fsh396ss gmail com gt Subject R 390 HP 3586B info please Hi Perrier Yes please am trying to learn more about my HP 3586B have not attempted the Electrolytic replacement yet it is too intimidating would be great to have a list Found the Beethoven test while learning about the unit No clue what the 15khz IF pick off is Date Sat 8 Nov 2014 22 59 09 0800 From Perry Sandeen via R 390 lt r 390 mailman qth net gt Subject R 390 Capacitor Group Buy The common denominator capacitor for the HP 3586 is 470 uF 50V The HP 3586B uses about 18 The capacitor is a Panasonic P N 667 EEU FR1H471B The common denominator capacitor for the HP 5370B is 105C 6 000 Hr 150 uF 50V The 3586 uses about 20 am willing to se
210. ased on the military version of the CA 5 had contacted him at that time and he thought it was a good idea just recently found out Nolan had a stroke and does not remember much would like to post this data before it is lost R390 site do not know what complications there would be because his test gear page 129 data was copyrighted but posted on the web It might also be a good idea if Nolon s data and imformation can be saved before his web site dissapears Date Tue 13 Dec 2005 20 04 19 0500 From Tom Bridgers lt Tarheel6 msn com gt Subject Re R 390 Low Audio Have you checked for leakage from the pot to ground have found many pots that tested okay as far as resistance goes but what tripped me up and caused problems in the circuit was that the pot was shorting to the pot case and therefore to ground at a relatively high resistance Some older pots are failing this way Heath VTVM pots are notorious for this From petesr Date Mon Oct 18 1999 11 01 am Subject Re R 390 R 390A Test Equipment Manual References Also NAVSHIPS 0967 187 5010 Formerly NAVSHIPS 92134A Instruction Book for RF Signal Generator Set AN URM 25D AN URM 25G and AN URM 25H Publication 31 Dec 1953 W Change 7 of 7 Dec 1977 N S 0967 187 5016 This is the 92134A publication with the 7 changes thru 7 Dec 66 included gt At 02 42 PM 10 17 99 0400 you wrote gt gt need the manual number NAVSHIPS T O etc Title and g
211. ast haven t noticed any problems with strong signals other than bc stations need about 20 db atten on the front end built in attenuator is there for that to behave nicely a known characteristic of this radio And the other receiver also is comparable but has some other dial repairs and intermittents that I m trying to remedy Dan From Bob Tetrault lt r tetrault attbi com gt Subject RE R 390 xtal wave spikes Date Tue 26 Nov 2002 17 34 43 0800 Dan The 1N82a s are a similar RF type diode as compared to the 1N34 While the turn on voltage is lower for a germanium as you pointed out the oscillator voltages still seem marginal They can still be found though don t know where think a suitable newer tech replacement would be the Schottky type which has a similar turn on threshold Matching them would be easier than the old one they are much more consistent in the processing and in any case the matching need only amount to a match of the forward voltage as measured by a DMM in the continuity mode The Mini Circuits MCL mixers are 50 Ohm devices which might work with a cathode follwer as the LO driver but not with test gear page 77 the IF output which am sure in your case is probably very high impedance as most toob circuits were designed for such levels The MCL diodes are Schottkys take it that this is a mod Or a production design If it is a production design it would explain the BC band performance issue Sure
212. at Bandwidth determines the bandwidth of the sweep triggering signal though the 54xA and 56xA used a tunnel diode trigger with lots of bandwidth but it was still limited by the vertical amplifiers Date Fri 2 Jun 2000 12 25 31 0700 PDT From John Kolb lt jlkolo cts com gt Subject Re R 390 Need Advice on O Scope Don t make the mistake of picking up the common 5000 series plug ins for them they don t fit Date Wed 31 May 2000 18 59 15 0700 From Wayne Rothermich lt rother impulse net gt Subject Re R 390 DQT Was Need Advice on O Scope Barry It depends on the plug in but most 560 series vertical plug ins are 10 MHz bandwidth You can check this with a sine wave signal generator by increasing the frequency until the peak to peak envelope reduces to 70 3dB Be sure to terminate with 50 ohms at the scope input and be sure the generator itself is not rolling off Alternately a pulse generator can check scope risetime The scope bandwidth will be about 1 2 8 t Again be sure to terminate in 50 ohms and check that the pulse generator s own rise time is much faster than what you measure have a 564 storage scope and find it to be a very good scope for low frequency work Sampling plug ins are available to extend its frequency response for repetitive waveforms to the GHz region Date Fri 02 Jun 2000 18 55 53 0400 From Glenn Little lt glittle awod com gt Subject Re R 390 Need Advice on O Sco
213. at helps is to put mesh grounding collars gt on the shafts of rotary switches capacitors and potentiometers to gt ground the shafts to the cabinet look inside the front panel of an gt HP8640B for an example These days you will probably have to make gt your own coarse stainless steel wool works OK do NOT use regular gt steel wool gt gt If the input jack of the DUT is floating not galvanically connected gt to the chassis right there at the jack make sure the body of the gt connector is RF grounded using a 0 01 0 1 uF capacitor best practice gt is to use the cap in parallel with a 10 100 ohm resistor This gt applies to any other floating connectors as well not just the input gt jack You also may want to wind 10 turns or so of the cable gt connecting the sig gen to the DUT around a ferrite toroid core Type gt 43 say 2 4 OD to keep any QRM QRN riding on the shield from gt getting to the DUT input Put this choke immediately before the gt external attenuator or the DUT input if you are not using an gt external attenuator but understand that if you are putting 130 gt dBm and lower signal levels into the sig gen end of the cable you gt are unlikely to get good results no matter what else you do gt test gear page 383 gt If you have a chance taks a Harris 590 apart and observe what they gt did the 590 is the best RF sealed receiver have seen gt interesting
214. at it s rated this way due to a possible stack up of tolerances If the meter is off 2 and each of the resistors in the attenuator are also at one end of their 1 spec you could end up being a max of 10 off guess If the resistors and meter are on the money the accuracy potential should be a lot better than 10 Know that both of mine are removed disassembled and tweaked the calibration of the meter in my D model It is exactly 100 ua at FS and was under 1 max error across the scale The meter in my F model was off probably 10 and it s internal resistance was high had a spare meter that was within 2 so swapped it out Sooner of later I ll either clean and recalibrate the old one or find another Burlington 100ua meter that can swap the meter face with if the internal resistance problem isn t fixable All of the resistors in the attenuators in both the D and the F are within a couple of tenths of an ohm of their marked value I d guess that they re within less than a half of a percent A few were only a few hundredths of an ohm off Granted a nice lab grade HP signal generator or an external Tektronix attenuator pad is going to be more accurate Unless luck into one locally at a good price don t really see a need for a more high tech signal generator for my needs gt Sure would like to get this URM25 right before button it up Hell I ve been working at going thru the Collins R390A for well over a y
215. at the photo which is pretty blurry don t know think it s set on 50 ms looks more like 100 or 200 ms On my scope 50 ms is above the separator between ms and s ranges with 50 ms at 9 o clock and 100 ms and 200 more like 8 o clock which is where think the time div is set on the auction picture Dan Date Tue 10 Nov 2009 15 06 07 0500 From Shoppa Tim lt tshoppa wmata com gt Subject Re R 390 OT bought a scope I m not sure if it s a factor of ten in the good direction but there s a button Under the screen if you hit it it stretches the horizontal axis by times ten It produces Confusing results until you figure out that the button is engaged My kids come in my shop and hit that button all the time and it can take me a couple of minutes to figure it out Sometimes and am no newbie to the 465 The fastest and slowest sweep rates can be chronic problems on any scope and while the Teks Are good they can get out of whack too know that calibration is important to many but far and away the most value in a scope comes not from any absolute calibration but the fact that you can get a picture of a waveform Regardless of whether the scales are right or not Date Tue 10 Nov 2009 15 15 52 0500 From Barry lt n4buq knology net gt Subject Re R 390 OT bought a scope test gear page 210 I m not sure but it appears there are two indicators at work on the delayed sweep Settings rotary switch one for channel A and
216. aterial as it doesn t exactly apply to an R390 Date Sat 1 Aug 2009 12 56 07 0500 From Barry lt n4buq knology net gt Subject Re R 390 OT Problem with HP 606A linearity Yes it was you and a fellow from another list who used to work at HP and seemed to know this was the right way to go Yes do plan to try to at least move the saddle point the plot looks kind of like a sine wave in an attempt to at least get the dial within spec If there are other things can do to reduce the errors I d be interested in knowing what they are hope it doesn t involve rebending those fins though One thing that was curious about is a 2pF cap across both tuning caps it is a push pull oscillator wonder what it s purpose is and whether it might warrant replacing have a dipped silver mica for it but didn t put it in place as didn t want to replace what appears to be a factory part if it isn t bad Date Sat 1 Aug 2009 14 30 24 0500 From Barry lt n4buq knology net gt Subject Re R 390 OT Problem with HP 606A linearity Interesting update changed the points where am setting zero Instead of setting them at the absolute endpoints used points closer to the points where test gear page 205 the error was the worst used 600kc instead of 530kc for the low end and 1700kc instead of 1800kc for the high end It makes the entire scale have a maximum error of 0 8 with each endpoint being out 0 6 and 0 6 respect
217. athodes emitters and sources are preferred over plates collectors or drains Inputs to high impedance dividers should be used rather than the midpoints Be aware of the fact that the input impedance of a probe varies inversely with frequency Example A probe having a bandwidth of 50 MHz and an input resistance of 10 megaohm at DC would have an input resistance of approximately 1 5 Kilohm at 50 MHz Choose the probe with the lowest possible input capacitance and highest input resistance for best overall signal fidelity Date Thu 15 Jul 1999 16 11 33 0500 From Terry Muncey lt tsm electrosys com gt Subject RE Tek scope 502A Do you have the maintenance manual and schematics for this scope Thanks in advance W Li test gear page 2 Yes catalog R29127 cost is 51 80 real big manual S amp H you can order direct on the web at http www radioera com order htm if you want Date Mon 19 Jul 1999 15 47 50 1000 From Morris Odell lt morriso vifp monash edu au gt Subject Re R 390 Tek scope 502A gt nearly working Tek scope 502A for 40 Can anyone briefly send me some gt specs before lash out for the 51 manual love test equipment too and in fact a 502 was my first Tek scope still have it in the basement storeroom The 502 A was a high sensitivity true double beam scope which was sold to biological research and electrophysiology labs It uses a special double gun double beam CRT and thus has two completely
218. ating transistor and a pass transistor You can use a resistor and zener off the unregulated B to develop a 24 or so volt supply for the op amp Another resistor and a voltage reference of your choice zener or fancy reference chip will give you the reference to feed to the non inverting input of the op amp The op amp output feeds the base of a common emitter transistor or the emitter of a common base transistor the collector of which goes to the unregulated B through a suitable resistor The collector of that voltage translating transistor also goes to the base of the pass transistor which can be connected as an emitter follower collector to B emitter to the load or as a common emitter amplifier emitter to B collector to the load A voltage divider from the regulated output load connection feeds the inverting input of the op amp A small pot in the voltage divider gives you a little adjustment range A few resistors and clamp diodes here and there to avoid catastrophe on power up and power down and you are all set If the supply is to produce regulated 50 volts the voltage translating transistor will be NPN regardless of whether it is connected common emitter or test gear page 163 common base The pass transistor will be NPN if it is an emitter follower or PNP if it is used in a common emitter configuration Note that the inverting input and noninverting input of the op amp may be reversed depending on whether the voltage tra
219. ation on how to construct purchase a replacement All my handbooks and radios are in storage awaiting the move Date Sun 07 Jul 2002 19 24 13 0700 From Dennis L Wade lt dlwade pacbell net gt Subject Re R 390 no subject Ron s question brings up one for me Could someone summarize the differences between the B what have and the C models of the HP 410 Dol need to start shopping for a C model now Date Mon 08 Jul 2002 07 26 34 0400 From JAMES T BRANNIGAN lt jbrannig optonline net gt Subject Re R 390 no subject The C is a transistorized version of the B Physically they are completely different The RF probe is a plug in otherwise believe the specs are the same had two B s they and their probes died found a C at Fair Radio a few years ago It is a nice to have piece use it to align transmitters test gear page 66 Date Sun 4 Aug 2002 12 40 41 0700 PDT From John Kolb lt jlkolo cts com gt Subject Re R 390 HP400e gt Anyone familiar with this piece of gear and how it copares with a 410 x series Tnx Entirely different animals the 400 series are AC only voltmeters for measuring AC signals from 1 millivolt to 300 volts FS full scale from low freqs up to about 10 MHz The 410 series is more closely related to the classic VTVM s vacuum tube voltmeter from RCA Heath EICO etc It measures DC voltage and current AC volts and resistance AC voltage is measu
220. ator from Collins picked up a Boonton Signal Generator at a recent hamfest The info on the top of the lid says Supersonic Oscillator Type 210 A 115 230V 50 60 cy SER 272 Boonton Radio Corp Boonton NJ USA On the back is a tag that says Collins Radio Co test gear page 101 Engineering amp Research Division SO it sounds like it was a good tool in the Collins labs I d like to do a presentation on this piece of equipment at my next antique radio club meeting can t seem to find any info on it I ve poked around on the web and see lots of references to a Boonton 211 but not a Boonton 210 Can any one point me toward a manual on this Thanks for any help you guys can give me From Scott Barry Clyde B lt cbscott ingr com gt Date Mon 22 Mar 2004 09 29 53 0600 Subject R 390 Signal Amplifier Needed When I use my signal generator usually connect my frequency counter to the output to monitor and accurately set the generator s output know this is generally not needed but for some things accuracy is necessary The problem have is the counter needs a fairly strong signal whereas the circuit in question may need a very low signal so end up switching the output level up and down It can get pretty annoying especially when a very loud signal suddenly comes through the radio Is there a simple circuit could build perhaps an op amp or two that could amplify the signal going to the counter while at
221. ators Yes the ultimate test is in the gear but there are some considerations However you are correct both down under and up over we must avoid even the appearance of wimpiness After all our respective national anthems include words such as bombs bursting in air and you ll never take me alive said he nasty rumor he was the first toob jockey kept his caddy on a pole way ahead of his time There seems to be some concern about which tube tester to buy Just make sure it s a manly tube tester In most cases this can be determined by the aroma after it warms up a kind of English Leather smell only funkier More meters the better Painted and re painted gray with stenciled lettering even better Heavy better still you can do weight training to build up your shoulders and biceps All those switches and levers help maintain hand strength G day mate Barry Date Tue 26 Jun 2007 11 57 30 0500 From lt pulsarxp earthlink net gt Subject RE R 390 Tube testers love my TV 7 tube tester and use it all the time Very useful to me and I m the Chief Operator and Chief Engineer at WOVT Also stayed at a Holiday Inn last night Date Tue 26 Jun 2007 13 10 38 0500 From Barry Williams lt ba williams charter net gt Subject Re R 390 Tube testers have a tube caddy that was part of a deal It still had some of the tubes in it Most were the American 5 types Date Tue 26 Jun 2007 14 3
222. attenuator DC resistance It was 61 Ohms at the 100 000uV position and 51 1 Ohms on the rest Also checked actual attenuation of each position except 30uv and below Each position was within 0 3 Db don t remember the the total error Used a frequency selective VM for this The matching pad measured 19 8 Dbv Again thanks to All Al Date Fri 23 Feb 2001 01 18 44 0600 CST From Don Reaves lt dr cei net gt Subject Re R 390 URM 25 Darrie operating instructions and repair manual for the URM 257 ftp militaryradio com pub militaryradio Manuals courtesy Nolan Lee Date Wed 5 Sep 2001 07 26 25 0700 From Bob Tetrault lt rstetrault home com gt Subject RE R 390 recommendation for rf signal generater Buy a URM 25 from Fair or elsewhere and use a counter You can t buy a good low cost digital display sig gen They are a contradiction in terms The shielding has to be doubly or triply watertight the attenuator has to be even better than that and the counter is incidental It s physical shielding don t come cheap unless it s test gear page 323 used and the URM 25 is the most readily available though prefer the HP606B it has a better attenuator Date Wed 5 Sep 2001 11 58 25 0400 From Tom Leiper lt twleiper juno com gt Subject Re R 390 recommendation for rf signal generater Agreed And counters in that frequency range are CHEAP and accurate and allow you to do other things like align yo
223. ausernet com gt Subject Re R 390 Meter Meister lt snip gt Probably not particles or misalignment of the armature then Sometimes I ve come across such severe static that a meter won t zero just hangs wherever you point to on the glass Mostly happens with plastic lenses doubt if that s it given the vintage and so on and that usually clears up sitting around or when subject to some current Have you tried running the meter out of it s case Does it have a range switch with precision resistors Maybe one is bad You said it won t go above 2 volts but will peg with reversed polarity how much swing between zero and peg left Might be 2 volts or less Does it have other ranges Date Sun 15 Jun 2003 22 30 38 0400 From Barry Hauser lt barry hausernet com gt Subject Re R 390 Meter Meister As for tools a jeweler s screwdriver nutdriver set and improvising like you with paper toothpicks etc As for handling verrrrry careful You have to be particularly careful with steel tools around them that can snap to the permanent magnets Also be careful just moving your hand away there s a tendency to snag things Sometimes you can manipulate the shaft back in place by finessing the outer turns of the spring very lightly bumping it And after all that it s not a sure thing Might be worn out or an open coil A true meter mechanic can go as far as rewinding them but that s beyond me Very expensive hear From
224. ay 2003 21 24 14 0400 handling is 5 95 though above the shipping cost which makes it pretty much a regularly priced DVM Rat Shack From TheFirebottle aol com Date Fri 9 May 2003 21 35 24 EDT Subject Re R 390 Re OT CHEAP DVM S Heh heh There had to be a catch regularly work around high voltages in the industrial chiller business don t think would want to trust one of those on 660 Volts Just my 2 cents worth From Jim Simmons lt jimsim adelphia net gt Subject Re R 390 Re OT CHEAP DVM S test gear page 84 Date Fri 9 May 2003 21 55 08 0400 Strange when went in to pick one up the only thing the tacked on was the sales tax From Darryl Jones lt sherri darryl erols com gt Subject Re R 390 Re OT CHEAP DVM S Date Fri 9 May 2003 22 02 24 0400 Qty Item Description Price Item Total 1 30756 4VGA 7 FUNCTION MULTI TESTER 2 99 2 99 Subtotal 2 99 Tax Rate 0 00000 Tax Amount 0 00 DE 2 95 Shipping 2 95 Handling 5 95 Total 11 89 Maybe it s to do with my zip being on the east coast From Kurt lt r390auser cox net gt Date Sat 17 May 2003 14 24 43 0700 Subject R 390 ME 26D U recently picked up a ME 26D U multimeter with the tip of the RF AC probe broke off Does anyone have or know where can get a replacement cap with the probe tip or a complete probe or a junker ME 26D U with a good probe tip How many of these units are in use by members of
225. ay case a Bud minibox with a standard 9 pin tube socket at the other end and a 6 pole two position non shorting wafer to switch the plate grid cathode leads between the two triode sections all built out of junk box parts in an hour Works swell to rapidly screen through those one dollar hamfest 5814A s before actually test them in a receiver Parenthetically though think that tubes are best evaluated in a real circuit lt snip gt Date Thu 4 Aug 2005 13 28 25 0500 From Jim lt jclark6 gmail com gt Subject R 390 Tube Tester test gear page 124 assume everyone has strong opinions about this so will ask what Type Tube Tester would you recommend Make and model am thinking about picking up a tester and know nothing so will ask those who do Thanks Date Thu 4 Aug 2005 14 48 06 0700 From Tracy Fort lt beerbarrel cox net gt Subject RE R 390 Tube Tester Date Thu 4 Aug 2005 17 32 48 0700 From Dan Merz lt djmerz 3 cities com gt Subject RE R 390 Tube Tester Jim I ve owned Hickok 600a 6000 750 and TV 7 got rid of the 6000 because it didn t have sockets for the older vintage tubes almost always use the Hickok 750 because have more tube settings data for it than for the other two and it can put a lower plate voltage on some of the old tubes The 600a is quite popular with users of vintage tubes and there s a lot of data for how to use it with those tubes including Western Electric tubes
226. b 2000 13 01 07 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 URM 25 D Question No the D model might be a pain to work on but there s a zillion of them and the later D clones out there The spare parts availability documentation and knowledge base is far better than that of the F model Keep it and re cap it It s easier to go thru the extra work with your D model than have to find a buyer for it and ship it find a seller of a URM 25F in as nice a condition as your D model sweat the shipping find a manual etc test gear page 305 Date Thu 16 Mar 2000 17 10 24 0600 From Tom Lutz lt telutz pclink com gt Subject Re R 390 frequency counter You are correct mine is the Radio Shack 22 306 You are also correct in that the sample size is somewhat small But for what use it for it works great Usually leave it hooked up to my URM 25 as a read out and find it very stable and accurate against other standards Date Tue 16 May 2000 20 15 33 0400 From Mort Denison lt mdenison blazenet net gt Subject R 390 RE URM25D Woes want to thank everyone who kindly offered to fix my signal generator At the suggestion of a list member called up Fair Radio and talked to RJ their resident URM25D guru to see what was available and what he had to suggest Although they had no URM25D s or URM25F s at the moment he told me was in luck It seems that when they were plentiful they would part them o
227. been there and in use as long the only others i know of are some of the custom test jigs in the rocket test cells some of those have been around since the 50 s Tom KA4RKT For the curious work at Arnold AFB AEDC in the metrology lab PMEL Loads of fun every day and all the assorted test gear can calibrate Date Sat 20 May 2000 10 12 31 0500 From Randy amp Sherry Guttery lt comcents mississippi net gt Subject Re R 390 Instruments Ken You ve gotten some excellent answers so far but one point hasn t been mentioned at least haven t seen it so far and that s display response When doing alignment digitals can be real hard to interpret because you have to constantly evaluate the reading to determine the peak An analog needle meter has a huge advantage because it isn t constantly changing and it s very easy to see the peak as you tune through it While have an HP 410C on the bench and IMHO it s about as good a VTVM as you can get at a reasonable price also have an EICO 232 on the bench which is very good for quick and dirty measurements And as others have noted these can be found at HAM fests etc for 5 15 dollars often in really good condition Date Sat 20 May 2000 09 12 42 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 Instruments You re right Randy But the analog meter will float so it has to be done slowly to get the highest part of the p
228. been used in an old CD bunker My friend the rescue man went so far as to purchase a set of adaptors for Compactrons and Nuvistors and also some test sockets with nice terminals to easily make voltage measurements without accidentally picking up B on your fingers in a rats nest under the chassis He tested One tube and there it sat on his shelf traded him a very sick National NC 500 for it and we were both happy use it as follows test a few tubes at lunch once in a while and sometimes after the kids go to bed After keeping some for my BA s the audio boys get to fight over the bulk of those they find desirable _P6 miss the ballast tube thread ducking and running Date Tue 26 Jun 2007 22 49 25 0000 From odyslim comcast net Subject RE R 390 Tube testers Hey All Im a wimp too And buy my insurance from a Gekko Date Tue 26 Jun 2007 18 31 36 0500 From Rick Brashear lt rickbras airmail net gt Subject RE R 390 Tube testers think most of us use tube testers from time to time do and they are a good way to get a feel for what s going on in a dead or poorly operating circuit However if you have a known good tube you can substitute it is the sure fire way to know if the tube is the culprit have several known good tubes use for that purpose only When was in the TV repair business many years ago that was standard practice don t think one should ever put all of his marbles in on
229. bes New tubes are more noisy than aged tubes Old tubes are noisy again swap the IF and RF tubes around to find the arangement that yields the best signal to noise ratio you can get Realignment get the setting closer Practice alignments gets you more skilled at setting the exact point that is the peak point After you do the tube test and find the arrangement of tubes that yield the best performance do the RF deck alignment about three times The manual says go from end to end on a band until you peak out the band That s once Its an understanding and feel for your test equipment that is more important than any thing else Date Fri 21 Jan 2000 19 01 30 0600 From Randy Guttery lt comcents mississippi net gt Subject Re R 390 VTVM vs DVM Hard question to answer because there isn t any right answer There are consideration to entertain then make YOUR choice Most modern DVMs are far more accurate than most VTVMs Most DVMs are harder to read because unless the voltage to be measured is pretty stable the reading jumps around all over the place Trends peaks nulls etc are harder to watch 10M a couple of pf input isn t bad for either a VTVM or a DVM so there it s a dead draw You mention measuring E208 et al While a DVM might give you a more accurate absolute reading a VTVM will give you just as accurate relative reading i e if you re looking for an AGC problem in the chain even if the VTVM is o
230. bes with good high frequency gain and low noise characteristics Date Wed 27 Oct 2004 22 10 10 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 RE tube testers test gear page 113 Pretty much what am proposing is a simple transductance tester that runs at 60 Hz just like the TV 7 and TV 10 testers did That makes the circuit fairly easy to build and just about any reasonable AC voltmeter can be used as the detector in the plate circuit A quick scan of the tube tester schematics suggests that a fixed bias goes on the plate and screen A variable dc bias goes on the control grid along with about a volt or so of AC suspect we would use something like a dozen or so resistors to set the whole thing up for the tubes in the R 390 The advantage of doing it this way is that the data from the TV 7 or TV 10 can be directly compared to our tester This will give us a way to be sure that we got the design right have never seen a frequency drop off in a tube Certainly they do get noisy but they don t seem to get roll off problems You can see capacitance variations but those are normally tuned out in the circuit We could measure electrode capacitances and that would give us a pretty good idea of what is going on suspect that we wouldn t find out to much though In order to measure high frequency gain on a tube we would need a tuned load to run into The same thing would apply to the grid circuit If you are going to do t
231. block You should be able to lap it flat without removing it s innards Just make it a point to clean the surfaces before you flipped it over read somewhere that copper screen strips placed across a surface to be sealed is better at containing RF than a perfectly mated dead flat surface don t know if it s true or not but Doc should know If it does indeed work that well if might be worth just laying a piece of copper screen over the casting before installing the cover Doc Maybe some ferrite beads on all of the wiring that feeds into the casting at the bypass caps meter leads etc gt Any suggestions for optimizing stability Replace all of the know problem caps Verify that all of the tubes are good and gas free Use a 6AG7Y The Y is for a low loss base I m sure that the Govt specified that tube for a reason The totally different F model uses it in addition to the D and it s clones Either do one of the regulated voltage doubler mods for the osc tube filament or run the entire thing off of a constant voltage supply Replace the voltage regulator tube with one of the industrial numbered ones with tighter regulation Dismantle the attenuator and clean it s innards and lube it s bearing points with synthetic oil Don t sit it on the bench you re working on Oh and most importantly do not consume anything with garlic in it for at least 72 hours before using it lt grin gt Date Fri 15 Dec 2000 22 00 46 0500 From Barry Hauser
232. both are good RF signal generators The band switch drum is different You cannot mix and match D and E mechanical parts Tubes are tubes and caps are caps you can repair either if they ever need it Accept what you can get Do not pay a lot more for a new E than an older D Roger KC6TRU Date Mon 14 Nov 2005 19 13 23 EST From Bonddaleena aol com Subject Re R 390 R390A URM25 Expect to recap it My D model had several large micas cracked and leaking oil all over the inside All that heat and nowhere to go made a ss replacement for the rectifier and it runs a lot cooler ron Date Fri 13 Jan 2006 12 52 56 0600 From Brad Huff lt huffo avalon net gt Subject R 390 signal generators have seen a few comments about the URM 25 vs the HP 606A and we all know that the HP 8640B is far superior to these What is the general feeling about the Boonton 103B In today s world of cheaper surplus test equipment is it of any value to own a URM 25 Brad Date Fri 13 Jan 2006 13 18 21 0600 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 signal generators had a URM 25 after having used many different signal generators professionally and found it clunky to operate and a bit confusing Those that were raised on them will probably disagree but that s OK it s a personal thing gave it to my brother and bought an HP 606A It s big and heavy but it s rock solid and very test gear page 357 straigh
233. bout 350MHz recall but it had a very much smaller display due to the physics of deflecting a beam at high speed The 7000 series were mainframe scopes that replaced the 500 series These were nick named new gen for new generation They were solid state had a very innovative switching supply and were built in 3 or 4 hole versions There was a 7403 and maybe a 7404 meaning 3 and 4 holes respectively In the 3 holers you could put in two vertical plugins and one horizontal In the 4 holers it was two of each The chassis 74xx or 77xx don t recall if they did a 75xx and 76xx but think they did the 78 and 79 was capable of different speeds For example the CRT was and still is the determining factor in how fast a vertical trace can be deflected This is due to capacitance of the plates physical configuration of the CRT acceleration voltage etc The 77xx series were faster than the 74xx series by quite a bit if you used the faster vertical plug ins because it used a higher speed CRT It also had more bells and whistles built into the mainframe so it was quite a lot more expensive Tek had a series of storage scopes that used a phenomeon called secondary emmission where they would paint a single shot trace on the phosphor screen then through a low energy flooding of the screen the screen test gear page 14 would continue to glow where the orginal trace had been One of the 7000 series had this capability but I m not sure which one
234. brate a high accuracy inductance bridge and these things have sold at fests and auction sites for 300 apiece and more Measuring voltage is even tougher at home Systems to measure voltage to high accuracies is very complicated often involving shielded rooms calorimetric methods quantum physics based references and so on Voltage reference instruments can be had on the used market the would be quite useful to check our DMM s however Careful web searching will reveal a lot of good information about test gear page 122 electronics calibration The Agilent web site has interesting reading For example recently found a publication on Tips for Making Accurate Measurements or some such title Any one of the setup diagrams in that one included at least 50 000 worth of their equipment so it wasn t all that useful The NIST website www nist gov has lots of papers and reports but you have do dig for them the search engine is terrible and you ll read about methods and techniques impossible anywhere but a national calibration laboratory in many cases How many of us have a cryogenic system capable of cooling a Josephson junction array to four degrees Kelvin think there are many things we can do in our basement workshops to both check the accuracy of our equipment and give us many happy hours of time at the bench If you want to know whether your R 390A is hearing 1 microvolt or nothing lower than 50 you have a shot at it If you need t
235. but if you wait and watch you can usually pick one up priced right It can be as simple as using a megger type device with the crank on the side Works for fishing too if you don t get caught The important part is to check the caps at rated voltage can t say have ever found a Black Beauty or Brown Beauty that tested good all had excessive leakage As a result usually do a mass paper cap replacement but that is a personal thing Many only replace a few in the radio in key spots like the DC blocking cap that can cook your Mechanical filters in the A models and let the rest of the rock on Be sure to check out the Pearls of Wisdom documents and the nicely done Y2KR390 manual may have that name wrong Both are must have resources Good luck and drop questions on us anytime someone will always know the answer Date Tue 06 Mar 2012 20 15 40 0600 From Robert Nickels lt ranickel comcast net gt Subject Re R 390 Capacitor Tester really like Miles description of a successful troubleshooting method and would only offer a slight re phrasing of his statement above the most useful capacitance checker of all is the one between your ears test gear page 394 learned a lot by watching a ham and lifelong TV radio repairman knew Sk in action he could look at a circuit point his finger at what was most likely wrong and then make a quick measurement to confirm it That s how you make a living doing it for 3
236. can expect from it 2 Calibrate the URM 25 with that meter test gear page 338 3 Call the project done A couple of alternate methods come to mind Method A Find some recommended AC voltage detector circuits useful at the frequencies of interest Build one and assume the measurements are close enough This method may well involve very few components one diode one resistor one capacitor and a way to mount them and a DC voltmeter of moderate accuracy Ifa circuit reported to have good performance is duplicated carefully the results for these purposes should be quite good enough Method B Build such an AC voltage detector and mail it so someone who does have the likes of an HP 410C for calibration by comparison at some frequency ies of interest Upon its return use it to do the calibration Notes 1 seem to remember that the output calibration of the URM 25 depends on setting the signal generator section output at the input to the attenuator to 2 volts rms l believe that the GR 1001A and the HP 606 are similar Making an ac voltage detector that works well at 2 volts and over a limited range of low to moderate frequencies would be a rather simple job The URM 25 output voltage specifications is based on at last the following points A Calibration of the 2 volt point is done as specified B The RF attenuator is working properly C The generator output is terminated properly 2 Making very accurate RF voltage measu
237. ce checks 20K volt VOM A TV 7 will quickly cull out the bad tubes and give you an idea of which tubes are hot For convenience have found tube extenders useful in checking voltages Tube extenders make it a lot easier to access the pins rather than trying to access them under the chassis All the other gear makes things more fun to do appease our desire for engineering precision but are not required to do the job Date Fri 13 Feb 2009 11 55 25 0600 From Tisha Hayes lt tisha hayes gmail com gt Subject Re R 390 test equipment question Know that this is broaching on heresy to mention this found the URM 25D to be less than helpful when compared to a good signal generator It is drifty the impedance matching module is a joke and it is hard to get repeatable results when trying to chase the performance dragon But if you use a good frequency reference like the 100 KHz calibrator and that is not waay off and WWV you can get darned close to being on frequency If you dare to dabble with the compensation screws on the PTO to correct linearity you need a much better frequency counter and signal generator Of course gettting used HP Agilent equipment will cost you more than any one radio would ever sell for You can find a really decent HP 400 series VTVM or a Boonton that would do an excellent job on measuring RF levels for a song and a dance The original maintenance manuals were written around the inherent limitations of the
238. ce of leakage I ve asked this question before but received no reply What is the nominal input impedance of the unbalanced input of a 390A Would it not make more sense to use that input for any coax based measurements Any impedance adapters that use resistors to do the job such as the URM 25xx will add loss to the system The manual goes into coupling methods in detail and also cautions about accuracy errors do not have any basic long wire or balanced feed antennas here For most BA type of reception use Beverages coax fed multi frequency dipoles and verticals Date Sun 9 Jan 2000 13 04 39 0800 PST From John Kolb lt jlkolo cts com gt Subject Re R 390 URM 25D stuff I ve seen URM 25 attenuators for sale on the shelf at Murphy s Surplus http www maxpages com murphyjunk Don t see them listed on the web page but you can find the phone number there Date Sun 09 Jan 2000 13 32 26 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Signal generator connection questions gt That s not nearly the problem that putting 10 dBm into a piece of coax gt cable to radiate a bit and then go to the input amplifier of the counter gt where its boosted to 3 or 4 volts peak to peak square wave inside a gt single shielded at best probably not really shielded at all box to gt radiate directly to the single shielded at best receiver input test gear page 288 Interesting Doc never even really considered it
239. ch was liberated from a junked HP generator The attenuator is mounted in an available drive bay and the test gear page 279 generator output is available right on the front panel of the PC It s pretty nifty to stick a frequency counter on the output tell the PC VFO to go to 455kc and read 455000 on the counter lots easier than diddling the 1001 A s dial and holding my breath It comes with some simple software but wrote a small program with a bit nicer interface and the ability to save lists of frequencies so can plug in the list of marker freqs for my favorite receiver alignment and jump around with the touch on the keyboard It can also be made to sweep frequencies this works nicely if you have a reasonably fast PC use an ancient 386 16Mc motherboard that s a PC boatanchor now a days amp it s works great have no connection with these folks just a happy twiddler Date Sat 08 Jan 2000 10 48 21 0600 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 Signal generator connection questions The Times cable is probably good Sit down before you get a price on it and appropriate connectors generally use RG 223 for critical needs had a large roll from Collins surplus but used it all now I m using the remains of a coil of it bought either from Hosfelt or Mendehlson Electronics prefer crimped or Amphenol FCP connectors because think they get a better grip on the braid so it doesn t
240. chacuff cableone net gt Subject Re R 390 re test gear for your R390A The O Scope is a very handy tool at times have found the spectrum analyzer to be a most handy tool when looking for weird problems especially in crystal oscillators Typically expensive though they are coming down in price for older models that HP makes They drift around a bit until warmed up much like our beloved radio s but that s OK just power it all up and come back in an hour and go to work It s nice to be able to see the purity of a signal and do comparative level checks I ve found by using the spectrum analyzer can do a better and quicker job of aligning all the crystal oscillator trimmers in the R 390 URR s I ve done Easy to see the peaks and the harmonics to make sure the right one is being peaked Anyway it works for me If you end up with 5 or 6 hundred dollars that you want to spend on a nice piece of test gear for the bench take a look at one of the older used HP analyzers if you get one that goes down to cover the 455 KC IF you can do sweep alignments of the IF if your generator is capable That s another subject Date Sat 1 Oct 2005 10 16 58 0700 PDT From Michael OBrien lt mikobrien yahoo com gt Subject R 390 Hickok CA 4 data using Nolon Lee s TV 7 series data A few years ago had compiled data into an Excel spreadsheet using a Hickok CA 4 adapter with Nolan s spreadsheet for the TV 7 series tube tester Nolan s data is b
241. ching for someone with a hanger queen or you can buy several to keep on hand for solid state break downs So if it s just for keeping one old boatanchor R390 or R390 A working like a wonderful receiver a URM 25D will do Got more stuff in the shack some FM receivers etc could be time to upgrade bought the HP just for something to fix during the rainy season in Oregon Still fix n and the rains haven t stopped Date Sun 15 Jan 2006 10 34 54 0800 From Ed Zeranski lt ezeran ezeran cnc net gt Subject RE R 390 signal generators My URM 25F is still here in the line up because its portable lucked out a few years ago finding a pile of HP 606A B generators for 5 each in San Diego kept one and use it along with an HP 608D It is a pleasure to use Last year a Measurements 65B turned up and though old it looks to be a good unit butl have not had a chance to go through it yet For audio the old HP 200A and CD models are still hangin in there Date Sun 15 Jan 2006 13 58 10 0500 test gear page 358 From David C Hallam lt dhallam rapidsys com gt Subject RE R 390 signal generators have a URM 25D and a HP 606B The 25D takes up less bench space but the 606B is easier to use The delta f controls makes getting it on frequencyeasy and it is rock stable after warm up don t believe the 606A has an output for a frequency counter as does the 606B With any of these you need an external frequency counter to get on fre
242. ck Thanks for the link covering his papers didn t know about his group or would have emails containing the posts usually use that option where you receive emails of all the posts Too bad think have a complete file of Hollow State News subscribed while it was still active and ordered back issues I ll check when a return from a one week trip which starts tomorrow and ends a week from Sunday Date Wed 7 Mar 2012 21 06 20 0800 PST From Drew P lt drewrailleur807 yahoo com gt Subject Re R 390 Capacitor tester For leakage testing with a reasonably substantial applied voltage don t forget the method advocated by Dr Jerry This method uses a DC power supply in series with a high impedance voltmeter such as a DVM More about this method and multitudinous other R 390 topics will be found in Pearls of Wisdom at r390a net Date Thu 8 Mar 2012 09 00 10 0500 From Barry lt n4buq knology net gt Subject Re R 390 Capacitor tester gt For leakage testing with a reasonably substantial applied voltage don t gt forget the method advocated by Dr Jerry 05 thought about that after sent the post The only reason don t use that method is a lack of a good HV supply That s what makes the GR1617A so handy Date Tue 13 Mar 2012 15 01 07 0400 From rbethman lt rbethman comcast net gt Subject R 390 URM 25 info doc stumbled upon an envelope that got here some time back
243. cket to allow you to insert a current meter into the circuit I d call the TV 2 series the hardware hackers tube tester of the military ones It s a manly looking tester and simply owning one will boost your testosterone levels and put hair on your chest Number three on my list would be an I 177B with an MX 949A U adapter box Actually this is my favorite tester but in all honesty it isn t as versatile as more modern testers If you re into pre 1950 s radio receivers etc it should handle it just about anything you d need In addition it s real fast to set up gt I ve got a hamfest coming up in Raleigh in the early spring and want to know what to look for The killer any more is the cost I ve never paid more than thirty five dollars for a TV 7D I ve had at least a dozen pass thru my hands over the years and kept two My ugly one and a pretty one for a spare Lately I ve seen them hit better than three hundred dollars Several that I ve owned were free bought a like new TV 2B from Fair Radio as a checked model back around 1989 for a hundred dollars with all of the original spares etc don t even want to tell you what people have been paying for them today guess that what it boils down to is what you can either afford or are lucky enough to stumble into Personally test gear page 251 there s no way in hell that I d pay today s prices for a TV 2 or TV 7 series Much less the seven hundred dollars that I ve seen a Hickok 539C s
244. cks Get a BNC chassis mount connector Ground one pin of the Twinax connector file the BNC down till you can force it into the cable clamp on the Twinax one hook the BNC center pin to the other pin of the Twinax and push the BNC into the cable clamp after it s tightened in place Epoxy and a spot of solder will do also bought the right tap and drill I think it s 3 8 32 or 5 16 32 thread to tap the cable clamp ring and have made some very nice adapters equivalent to the military adapter that usually costs some 25 or more now a right angle BNC test gear page 208 chassis mount connector makes a nice installation and leads the feed coax parallel to the rear of the radio Oh forgot a bit of hot glue or epoxy will hold the two twinax pins in place you do need this or they will push back into the connector They are normally held in place by the two wires in the twin coax will also make an adapter to set the input transformer balance 68 ohms from the BNC center pin to each of the twinax pins balanced equal in phase feed One last thought if you want to be careful about your measurements and be assured that you are in the ball park with the numbers you arrive at for input voltage you need to consider the loading of the signal generator it needs 50 ohms at the end of the output cable to deliver the calibrated voltage You may decide to make an attenuator for the input to the radio such as 50 1 with 50 ohms and one ohm r
245. cod net gt Subject Re R 390 Multimeter The HP 410 B is one of the best Tube VTVMs ever made The last of the series had a light gray panel and a meter with rounded corners on the glass Nothing ever made by Hickok even comes close Hickok gear was service grade whereas HP gear was lab grade These units are a bit tricky to calibrate as they require dual triode tubes with fairly closely matched sections Usually a handful are required to get the right ones Once calibrated however they will go for years sometimes decades Rebuild the HP and forget about the junk from Hickok If you really want to up grade go for the solid state HP 410 C If you get one of these make sure that it comes with its ORIGINAL probe They are detachable and matched to a particular unit NEVER buy one without a probe as you will never find one to match and the AC function will be useless Date Sat 25 Nov 2000 12 11 57 0500 From JAMES T BRANNIGAN lt jbrannig optonline net gt Subject Re R 390 Multimeter The Hickok offered is a solid state model any info Jim Date Wed 29 Nov 2000 16 03 22 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 revised cal steps for MU 297 U AN USM 223 Thanks much I ll carry out that calibration next time have mine out AND have two of these things one of which has had a field modification to help measure diode forward drops assume The change is fairly crudely done an
246. comcast net gt Subject R 390 TV 7 U Square peg round hole Does anyone have a method for testing new tubes does not have identified test setup and data on a TV 7 U want to test tubes like the 6LQ6 Sweep Tube but it has a nine pin arrangement which is not compatible with either a TV 7 U There was a fellow in JA land radiomann that is how he spells it that built an adapter for testing tubes and a bit of a guide on how to develop new test data but now it is all in Japanese am not literate in Japanese for me it might as well be in ancient Egyptian Hieroglyphs Any help Date Sat 27 Oct 2007 21 42 56 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 TV 7 U Square peg round hole The adapter part is fairly easy You pick a close tube and wire it up so the pins come out in the right places More or less cathode to cathode filaments in the right place etc Pretty much all testers set up the grids in a fairly predictable pattern If you grab a TV 7 schematic and data for a couple of similar tubes it should be fairly obvious what they are doing hook these to the plate those to the cathode the rest to the control grid Depending on the tester they will do things a bit differently You depend on the fact that they are going to set up all pentodes the same way Bias on the control grid is about the only major variable Essentially you are measuring plate current with a fixed bias You can go through a lot o
247. compiled but can t find the url now I ll check tomorrow and see if perhaps still have the file on my workplace pc Date Thu 20 Dec 2001 16 49 31 0800 PST test gear page 331 From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 URM 25D info Ok here s what know When pulling the front panel out of the case the power supply stays inside the case the two cords have to be unplugged they are short almost too short to run the unit with the front panel out of the case A roll of electrical tape under the cast aluminum case makes the front panel sit still while running it outside the case Becareful of the two feed through caps on the bottom of the front panel they can be broken easily and should be relocated to the sides of the small case they protrude from They can catch when removing the front panel from the case Now the caps in question are on the PC boards on the right side of the set Inspect these closely to determine how you can move them out to gain access to the caps if you look at what saw you can just barely slide the wires over the posts and get some more room to work without major dis assemblage Don t ask me to explain it you ll see it before figure out what words to use If you have the manual go through the resistance measurements this will show any other problems too While you ve got it apart you have GOT to look inside the cast aluminum case this thing is cool The turret switch is
248. count for the spikes And noticed that for one of the xtals that thought was bad could get a 0 1 volt pp wave or maybe a bit lower at the cathode follower output but on the ring didn t get the waveform showing up so interpret that to mean that the output is barely there and not strong enough near the threshold But there may be another reason for this behavior maybe the operation is just erratic for that particular crystal This ll take a little more snooping on my part This particular crystal was diagnosed as not working several weeks ago but was working when checked it later and then was working again today at the particular location mentioned but was not at the other location By the way l m wondering if there is a replacement unit that might be put here in place of the 4 diodes since these were put in back when this type of mixer was just coming into the picture and they might not be as good as later units I m also wondering if you would ever find a matched set of 1N82a diodes to replace the originals Mini Circuits makes a balanced mixer but don t know if you could stick one of these in and don t know what kind of diodes are in these mixers At this point have no reason to think should replace the diodes but am wondering what if One of these receivers works pretty good and is on a par with the 390a as far as detecting weak signals so have no reason to think the oscillator level is really too low for the good xtals at le
249. cranking signal generator knobs 8656B s aren t what would call expensive but aren t being given away either maybe 400 600 for a decent one with a money back return privilege admittedly not pocket change but worth every penny The best part is what they DON T have which is nylon and plastic parts that are absolutely guaranteed to shrink crumble and self destruct with age applaud efforts to resurrect piles of defunct 8640B s with new replacement metal gear trains but for lots of reasons speed ease of use programmable memory and a much nicer display personally would never go back to an 8640B again even if somebody gave me one There are too many better affordable options out there Date Fri 19 Feb 2010 08 08 23 0600 From Barry lt n4buq knology net gt Subject Re R 390 HP 8640B Question Although it doesn t go down below 10MHz would have liked to have had this one eBay 320473707073 It appears to be in extremely nice condition but was at work and don t bid on eBay at work bid on a broken 8640B but someone else has outbid me and after reading some of this I m going to let someone else have it have an HP 606A but not really thrilled with it It is pretty hard to get it calibrated and still don t have it quite right and I ve pretty much set my sights on a synthesized generator Maybe one day I ll find one can afford Date Fri 19 Feb 2010 10 18 06 0600 From Robert Nickels lt ranickel comcast net g
250. customer It might have been dicier if it were the first time any tubes were replaced where all the originals would bear the set manufacturer s brand But old tubes were usually covered in dust and the customer often didn t look inside the boxes Well back to the subject of the value of tube testers Try this many of us have accumulated large amounts of various tubes NOS good used tubes unknown used tubes Some of these came from buys of boxes and bushels of a variety of tubes In many cases we don t even have the gear that the tubes plug into But if good they can fetch a good price whether NOS or used but if they are tested Tube testers are handy for sorting through and grading tubes for future use or sale or the trash Also there are some circuits which benefit from a tube with moderate output and it s easier to pick n choose with a tester than plug n try Not to mention tube matching as with push pull 6V6 s etc Probably the greatest value is in checking for shorts efficiently You can t use an ohmmeter for that and in circuit testing is risky at best In some cases they can be used to rejuvenate tubes For quick sortation and checking for shorts test gear page 152 gas grid emissions you don t need an expensive mutual transconductance tester In fact there are some more recent emissions testers B amp K that are pretty handy for checking shorts more elaborate lockout circuit for dealing with known false indic
251. d a defect in the AC probe that was non repairable assemblies are potted was able to successfully adapt a replacement probe for a ME 126 VTVM I think that was the number it is a Military knock off of the HP 410B to be used as a replacement Later bought a brand new HP 410C AC Probe off of Ebay Put the new probe meter combination through a calibration and it measures accurately and reliably Great meter also have a HP 410B that rebuilt and calibrated and a couple of the ME 126 s Too many meters for a small bench Need to clean out some From Glen Galati lt eldim worldnet att net gt Subject Re R 390 FS Hewlett Packard HP 410 C VTVM Date Mon 14 Oct 2002 17 04 05 0700 test gear page 73 You are correct on the 410C VTVM The AC Probe was a seperate option when we requisitioned ours in the Air Force back in the 70 s There may have been another NSN that included the probe as a Option for the government The units that we received were without the AC Probe and we had to requisition separately believe that you were referring to the ME 26 Series of VTVM s that the U S ARMY used extensively This was a predecessor to the HP 410 Series Multimeter and was very rugged in a squared off rectangular aluminum case The AC Probe was hard wired along with the rest of the test leads This probe was much larger in diameter The 1970 HP Catalog listed the 410C with or without the AC Probe PN 11036A The Meter and probe together cost 495
252. d although the meter springs are okay the actual coil is open guess the years finally took their toll Anybody have a meter movement or meter assembly for this VOM Or even another Model 785 for sale or trade Thanks Date Sat 16 Dec 2000 22 42 50 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 HP 410B C VTVM probe tube Its a tough act to accomplish better than 1 KV PIV and better than 95 rectification efficiency up through a few hundred MHz I ve not found diode other than the 2 01C that works Other tubes might work at reduced voltage but few are small enough to fit the probe without drastic RF performance destroying changes Hunting for such a diode rapidly teaches one to be gentle with the AC probe and to never drop it on the floor And makes the meter without one sell for pennies Date Tue 19 Dec 2000 01 12 06 0500 EST From Norman Ryan lt nryan duke edu gt test gear page 40 Subject R 390 TS 505 Electronic Multimeters Recently played with a few TS 505 s one TS 505B U and a couple of TS 505D U electronic multimeters VTVM They were used in servicing the R 390 and are referred to in the depot manual got interested in them mainly out of nostalgia but find they are very cool units in their own right despite the modern day digital gear If you have one gathering dust for one reason or another here are a few hints based on recent experience Since don t
253. d by the 1A1 Both were exceptional plug ins nolan Date Mon 22 May 2000 23 15 13 EDT From Kenneth A Crips lt w7itc juno com gt Subject Re R 390 Instruments RE The 1A2 is the best of the bunch This is interesting the 1A2 module has label on it that says AREA 51 don t suppose Techtronix still has manuals for this unit Thanks for reminding me about the spelling have corrected My spell check Just so you out there don t think there are anymore deals out there paid 20 dollars for all this Techtronix gear and two roll around stands of course that might be all it s worth The bottom line is have it with enough spares to keep it going for along time Date Fri 26 May 2000 02 05 25 0400 From eengineer lt eengineer erols com gt Subject Re R 390 probes Not all TEK probes are interchangeable have found this out the hard way We have some good scopes at work Tek 2445 TEK 2440 etc and some bad ones the 995 tek 220 The BNC ends on some of the NEW 220 scopes don t mate properly on the old scopes and funny things happen Some of the old TEK scope probes have a ring around the BNC to select 1x 10X probes and the new BNCs dont mate properly to this Just a warning Cheers Jeff Date Fri 26 May 2000 09 53 16 0400 From Michael Tallent lt mtallent concentric net gt Subject Re R 390 probes Once again now Everybody There is no C in the word TeKtroniX The P6006 probe should have a ground lead which clip
254. d from tube socket to tube socket or pulling the chassis In this case like a tube Transoceanic or other series filament setup it s a time saver You don t want to use a good piece of equipment to find out if a tube has a dead short that might take out a transformer We are also learning that an NOS tube valve is not necessarily forever There could be bent shorting elements that have occurred in storage repeated shipping around old latent defects etc Long term air leakage around pins has also become more frequent so there s something to be said for pretesting in even the simplest of emissions testers test gear page 127 before plugging em into the equipment The reject values for mil testers such as the TV 7 s seem to be set conservatively low Good tubes generally read well over those except for rectifiers and diodes which tend to be right on Seems to be designed to avoid excess tube jockying If you pay enough for a tube tester like too much chances are you ll be more inclined to use it to save tubes than to find ones to toss out Not sure how popular re tubing is on this list but if you re going to arbitrarily replace all yours please send the castoffs to me for proper disposal Barry Date Sun 07 Aug 2005 08 09 13 0400 From shoppa_r390a trailing edge com Tim Shoppa Subject Re R 390 tube testers I m not gonna say it s impossible to take out a IF or RF transformer or a coil or choke due to a tube short
255. d hookup wire over the insulation These are backed up right onto the socket terminals actually touching them A couple of these looked like they were touching between the 7 and 9 pin sockets which are right next to each other Also there isn t much clearance on the 7 pin by itself re dressed the terminals and wires to make sure they would be clear What made me suspect this the 7 pin socket was a bit loose Problem is that the mounting flange is too weak to stand up to the constant plugging and unplugging of tubes Even though the socket saver was tightly bolted to the original socket the whole business wobbled in the mount The best fix is to find another fiber washer to put under the socket saver on the outer panel side so when the thing is tightened down it pulls up tight against the panel I didn t think of it when had it partially disassembled but maybe a shot of DeOxit on the fiber washers that are there would have swelled them up improvised with a twist tie around the socket saver on the top panel side Another fix might be some epoxy around the base of the original socket where it meets the flange BTW this TV 7D U has a meter that says TV 7E U in it Anybody know anything about that Anybody know anything about that graphite like stuff test gear page 261 Date Thu 30 Nov 2000 09 51 14 0500 From rbussier lexmark com Subject Re R 390 TV 7 problem Barry hi was reading your post of the work done o
256. d involves one extra resistor and an added front panel jack Who has any details on that Date Wed 29 Nov 2000 16 00 23 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 revised cal steps for MU 297 U AN USM 223 gt Thanks much I ll carry out that calibration next time have mine out test gear page 38 One of mine had a bad trimmer so I ll get a round to fixing it when get a chance and calibrate it but the second is now on the money as far as calibration goes Good think I kept the old tube type GenRad audio generator or I d have had hell generating the 50 volts at 1000 hertz lt grin gt gt AND have two of these things one of which has had a field modification to help measure diode forward drops assume The change is fairly crudely done and involves one extra resistor and an added front panel jack have one original one and one with the mod Mine has a yellow jack and a red D engraved next to it in the front panel did a comparison while had them both out of their cases for calibration and the on mine involved removing one of the original resistors and replacing it with two 1 ones I d also like the info if anyone has it suspect that there s a MWO out there some where does anyone have the DAM 310 handy to see what the MWO number was Date Thu 14 Dec 2000 17 49 47 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Do it yourself TE Calibration gt Keep a
257. d the screw and tighten the lock nut 5 IMPORTANT Seal the lock nut with a bit of finger nail polish Duco Cement or similar 6 Lubricate the worm and drive gears grease the ball bearing and the front bearing of the shaft oil Treat the variable capacitor rotor grounding finger with just a drop of Caig De Oxit or Pro Gold 7 Close the whole thing up and enjoy your back lash free generator Date Thu 14 Dec 2000 11 00 23 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 URM 25 Stability Its not an 8640 Be glad its stable enough you can keep it in the receiver IF for minutes at a time without having to align with one hand on the signal generator knob Did the frequency drift mostly linear with time or did it jump test gear page 312 Either could come from a capacitor in the oscillator or buffer circuit Capacitors in the URM 25 weren t any higher quality than the black beauties in the R390 and need the same attention to replacement Mica capacitors or dipped silver micas sometimes contribute to instability by having air spaces inside but that s not often Freezemist and heat might isolate the most critical components to frequency stability Do you have the Dallas Lankford notes on the URM 25D Date Thu 14 Dec 2000 11 00 41 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 URM 25 Stability The tubes that respond to
258. d this resistor was open in that one as well Hope this helps someone Date Wed 07 Jul 2004 07 36 18 0400 From Veenstra Lester lt lester veenstra Imco com gt Subject RE R 390 URM 25 RF output measurement Assuming the response is modest offer my service to measure URM 25 x at a number of significant freqs and levels but please do not ask for every MHz at every 5 dB So since my days of actually working on 25 s is lost in memory what would be an appropriate set of frequencies and levels that should be verified according to the real experts here on the net The selective level meter in its relative mode should make checking out the attenuator for discontinuities a simple process use a pair of HP 436 power meters with standard and high sensitivity heads and an HP 3586 selective level meters Date Mon 12 Jul 2004 16 06 44 0400 From Veenstra Lester lt lester veenstra Imco com gt Subject RE R 390 URM 25 RF output measurement The following is useful when URM 25x meets modern test equipment dBm watts volts RMS volts P P 50 Ohm 50 Ohm 20 0 10000 2 23607 6 325 test gear page 344 15 0 03162 1 25743 3 557 10 0 01000 0 70711 2 000 5 0 00316 0 39764 1 125 0 0 00100 0 22361 0 632 10 0 00010 0 07071 0 200 20 0 00001 0 02236 0 063 dBm watts volts RMS volts P P 50 Ohm 50 Ohm MicroVolts 7 0 2 00E 04 0 1000000 0 283 100 000 13 0 5 00E 05 0 0500000 0 141 50 000 21 0 8 00E 06 0 0200000 0 057 20 000 27
259. d through filters adding layers of shielding improving power line filters capping the high level output jacks when not in use It might make a difference whether the cap is a plain cap or a shielded termination The results may depend on the construction of the shielded termination BNC connectors are not consistently grounded N or TNC do better for leakage There has to be attention to stray conductive paths between concentric shields which ideally will only be connected at the RF connection My best shielded test generators have double shields with the generator running on a battery with the switch on the inner box run through a piece of teflon or nylon The only metallic connection between the two shields is at the coax connector All shields can be generally improved by using conductive gaskets and sometimes by covering the joints with Scotch aluminum or copper shielding tape The tape is fairly expensive though I ve found it surplus occasionally and not a sure cure because the adhesive isn t a really good conductor Soldering the joints and seams often helps when they can be soldered and never need to be opened Fasteners on bolted joints should be fairly closely spaced If a box leaks doubling the number of fasteners may have a detectable effect unless they are already under an inch apart Controls tuning shafts and band switch shafts should be of insulating material never metal because metal through a hole bypasses the best shielding even w
260. days are archived Back a sentence or three mentioned URM 25 use in the early mid 60s in the Navy Those were used according to the basic instructions in the manual so maybe at 455Kc the test gear page 292 Navy figured IF bandpass what the genny could do and what was expected were close enough At the time the common shipboard F counter was a huge HP job with vertical strings of tube read out can t remember the nomenclature total pain so seldom used thus the radiation from a counter lead wasn t a problem The 25F picked up at a swapmeet checked out OK but when used it being careful to monitor with a counter of course got the radiation to the test RX Since have used the counter then taken it off or when testing at an even number 7Mc or such just use the zero beat Didn t someone run an F measurement contest a few years ago to duplicate the old ARRL tests Last thing need is another LM or 221 but can t pass one up when it goes for 5 and if not sold will hit the dumpster Same for an Grertsch FM 3s Lambkins and Millen GDOs old technology but just neat Right now have an LM set up with RAK RAL TCS and RBS will have to drag over the 25F then play Date Sun 09 Jan 2000 20 20 15 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 URM 25D stuff gt Maybe I m missing something here but what is so hard about replacing gt the 25D etc attenuator resistors Physically replacing them isn t too bad
261. des you through refurbishment avoiding many pitfalls worked on mine replacing almost all capacitors because they were bad not a shotgun replacement most resistors and the germanium diodes The Hollow State News stopped publication around 2002 as the Internet became more popular and think Dallas is no longer active He wrote many interesting articles in the past and test gear page 387 I m guessing he was involved in refurbishing AN URM25 D s used at an University in Texas Maybe someone has the article on line If not and if you are interested I ll scan mine Date Tue 6 Mar 2012 11 29 11 0500 From Steve Byan lt stevebyan verizon net gt Subject Re R 390 AN URM 25D Repair Info More This doesn t include the URM 25 rebuild info it s not a complete set of HSN but try these http mikea ath cx hsn issue 1 12 pdf http mikea ath cx hsn issue 13 25 pdf http mikea ath cx hsn issue 26 37 pdf have up through issue 53 in pdf form obtained via a pointer from the R 390 list don t remember which URL and my work web nanny is preventing me from checking them out right now but it s one of these gt There are additional HSN issues under Barry Houser s he became a SK gt since about a couple of years ago website gt http site298 mysite4now com barryhauser and click the Archives gt button more issues are there up to 53 gt sent this to Perrier but suppose the rest of you might have some intere
262. df Date Tue 6 Mar 2012 20 01 53 0500 From Barry lt n4buq knology net gt Subject Re R 390 Capacitor tester While there are lots of choices one of the nicer things about the Tel Ohmike and other testers like it is the ability to put a bias on the device under test DUT and measure leakage have a General Radio 1617B that will do that just bought a Marconi TF 1313 that s supposed to be a 1 4 bridge but doesn t have quite the voltage bias capacity of the Sprague or the GR I ve wanted to get a nice accurate digital cap meter for a long time but just haven t wanted to put down that much money for one yet don t really need that kind of accuracy for boatanchor work Date Tue 6 Mar 2012 20 07 58 0500 From Barry lt n4buq knology net gt Subject Re R 390 Capacitor tester and sadly to correct my own post the Marconi doesn t do leakage testing Don t know what was thinking guess can claim it s because it s new to me test gear page 392 Date Tue 06 Mar 2012 20 09 19 0500 From k2cby lt k2cby optonline net gt Subject R 390 Capacitor Tester You have asked a very simple question and you are going to get a very complicated answer probably one that is going to provoke quite a bit of comment from the rest of the guys on the list The very first point to consider is that most capacitors especially the failure prone paper capacitors used in the R 390 R390 A known as Brown Beauties
263. dio room screened as well as the rooms use to get to work in The stuff that invaded my receivers in San Diego and LA for years made reception almost not worth turning the radio on My site here in Westminster South Carolina is a lot better but not like a good screened room Just adding a top and bottom cover does not fix most of the problems Also just parking the receiver in a metal cabinet does not do much better Maybe if had the rack setting in several inches of water That expirment was conducted at least once at Phu Bia during a typhon could get a good ground and better shield the receiver Not that the screened rooms were all that great We would have operators come into the shop and ask us to to get our off that frequency as soon as we could because it was parked on some thing that was beating with some thing else on the antenna and killing the dit of real interest The real problem was we did have signal generators in the box that leaked and you could tune then to frequencies that would cause receiver interference Date Fri 2 Mar 2012 20 02 51 0600 From lt wb5uom hughes net gt Subject Re R 390 AN URM 25s lt snip ass but dont think a modern top of the line signal generator has the issue being referenced At least have not seen it in my limited playing with HF here at home with my commercial playtoy service monitors do know if leave the sig generator with a 3 foot jumper unterminated on the output wit
264. doesn t mean much without that information It seems to drop by a percentage of the reading that is the last two numbers of the display are the only ones that change no matter what the band it did it that at 455 kHz and at 3 Hz Date Fri 15 Dec 2000 08 18 56 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 URM 25 Stability gt CHECK THE SHAFT END PLAY lt snip gt checked my 25G and it exhibits this type symptom to a very slight degree Next time open it up l II fix it The 25F uses a totally different setup with a springy double belleville spring type shaft coupling had always figured that it was used for shaft misalignment problems After reading your post now suspect that it was to decrease changing the position of the variable capacitor due to in and out pressure on the tuning shaft Next time open up the 25F I ll look into that thanks test gear page 314 Date Fri 15 Dec 2000 08 22 12 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 URM 25 Stability gt There will always be gas leaks at the seals and running gt heater filament power alone can raise the getter deposit temperature and gt make it more effective at grabbing the stray gas molecules That s the gist of what had read thanks Doc Do you remember what the source was Date Fri 15 Dec 2000 08 30 24 0600 From Nolan Lee lt nlee gs verio net gt Subject RE R 390 URM 25 Stability There s a lot
265. draws positive current even though the anode teminal is still negative thank the Edison effect due to the space charge which causes space current and to a lesser degree the contact potential due to the dissimilar materials used in the cathode structure When the plate voltage is 0 V an EA53 is drawing 10 uA at 0 7 V about 100 test gear page 198 uA and at 1 mA it is up to 4 V and rising fast not surprising given the 0 5 pF plate cathode capacitance it takes a tiny cathode to get the capacitance that low which is also why the useful life of these tubes is fairly short Rated cathode current is 300 uA peak 5 mA for no more than about 5 mS at a time Extrapolating from the characteristic curve the current is probably about 100 nA for an anode voltage of 1 V and 10 nA for an anode voltage of 1 5 V Date Sat 30 May 2009 22 27 33 0000 UTC From rdavis7 comcast net Subject Re R 390 R 390 Digest Vol 61 Issue 39 Ok Barry here s the deal You forced me to move a mountain of good junk and come up with a perfect probe for your project Its a military grade probe with a nomenclature test probe mx 404 9B USM 116 Has the diode still in it Ruggedized probe body with a nice rubber sleve covering it Complete with cord 3 insulated conductors 1 bare Send me your shipping address off list and It will find its way to you Only have 1 of these guys sorry Rick K8BPJQ CCA 11437 Dayton bum rdavis7 comcast net Date Su
266. ds Date Sat 21 Oct 2000 14 39 48 0500 From Nolan Lee lt nlee gs verio net gt Subject R 390 Tek Scopes gt have several of the large variety Tek 5XX scopes in my 2000 sq feet gt basement am able barely move around in the basement now as it is a true gt obstacle course made up of radios and test gear know the feeling even with 12 foot ceilings gt What do you recommend do with the scopes No way am putting them gt on ebay or taking them to a hamfest too big and heavy and relatively gt worthless except as for heaters in the winter Sad isn t it remember being in awe of them during the 1970 s Hell still am They are a prime example of the US at it s best Quality engineering quality components and first class workmanship Some of the best manuals of anything ever built too with schematics that wish everyone had used still use a couple of my 5xx series scopes Granted that since the 7000 series scopes started outnumbering them their use has dropped If it doesn t take two hands to lift and carry it it s not a real scope played with one of the new cigar box digital scopes a few months ago No thanks gt am sentimental gt as well as used these types exclusively in the 60 s would give them gt away if some one came to get them Barring that am going to wind up gt stripping them and trashing the carcass Put together a list of what you have and post it in a few of the related
267. e R 390 Sources for HP410C AC Probe Make one It s nothing but a tube two capacitors and a 22 M resistor We used to build them in metal 35mm film cans but they re long gone so you ll need something else test gear page 192 Date Sun 17 May 2009 01 53 23 EDT From JRFKESRI aol com Subject Re R 390 Sources for HP410C AC Probe Sorry but believe that this information is incorrect Go to _http bama edebris com manuals hp 410c _ http bama edebris com manuals hp 410c and download the PDF Look at page 52 of 63 The probe incorporates a vacuum tube diode Therefore any substitute you may build must also contain a diode would suggest a signal type Good luck with your project Date Sun 17 May 2009 07 42 07 0400 From David C Hallam lt dhallam rapidsys com gt Subject Re R 390 Sources for HP410C AC Probe just read an article describing how to build a AC probe using an IF transformer can for the housing will dig around and see if can find it again Date Sun 17 May 2009 09 47 36 0400 From David C Hallam lt dhallam rapidsys com gt Subject Re R 390 Sources for HP410C AC Probe The article is in the June 2008 issue of Electric Radio It is titled A Weekend Project An AC RF Probe for the HP 410C Voltmeter The 410B and the 410C used the same probe The differences are early versions of 410B used a diode with a different filament voltage so you have to check that and the the probe for the 4
268. e R 390 test equipment question However do try to get WORKING test equipment having to fix your equipment before fixing the radio you actually care about gets tiresome Date Fri 13 Feb 2009 08 16 07 0800 From Craig C Heaton lt wd8kdg worldnet att net gt Subject Re R 390 test equipment question test gear page 177 What is on your test bench now will get the job done Add a 600 ohm resistor to hang on the speaker terminals to check the signal noise to noise ratio never needed more than the items you have already listed Other pieces of test equipment might make trouble shooting faster but will those failures occur Not to restart the capacitor beat the dead horse discussion a cap analyzer that test caps at rated voltage is nice but one could save the money to purchase said item just buy the caps and replace BBOD s etc before plugging the receiver into a wall outlet Date Fri 13 Feb 2009 10 03 45 0700 From Richard Loken lt richardlo admin athabascau ca gt Subject Re R 390 test equipment question gt However do try to get WORKING test equipment 0 Poo Such sacrilage It is a time honoured tradition that your test equipment will have quit working when you need it You have a greater sense of accomplishment if you had to repair the VTVM and at least one of the scope probes before addressing the main problem Date Fri 13 Feb 2009 11 16 43 0600 From Mike Andrews W5EGO lt mikea mike
269. e Sun 9 Jan 2000 13 52 42 0800 PST From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 Signal generator connection questions As much as one of these leaks why can t you just put the included antenna on the freq counter and read the leakage Also how does one set the frequency of the URM 25 D to 455 Hz exactly without a freq counter don t trust the dial that close and its a long ways from any calibration point Date Sun 09 Jan 2000 15 59 38 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 URM 25D stuff test gear page 290 wish that they were local to me As common as it is for the resistors in the attenuator to be damaged I d be hesitant of buying one without being able to check it out by measuring the resistance values across the output as it s switched thru all of the steps There s a good chance that they were removed because they needed to be replaced Even still if they were cheap they d be worth picking up for the remaining good resistors have a spare one for my URM 25F but not for the URM 25D The resistors in the attenuator for the URM 25D model are the same as the URM 25F even though the attenuator itself is of entirely different construction They re also the same as the ones in the URM 25G H J L etc The earlier models like the URM25 and URM 25A used an output impedance of 53 5 ohms As a result the various adapters and the attenuator resistors are totally different values
270. e 335 barely dented URM 25 from 24 inches Now power up each unit and check functioning as per manuals Sorry for all the bandwidth on this consider it a Christmas present but don t try to return or exchange it tomorrow lt Date Sun 28 Apr 2002 22 24 34 0400 EDT From Paul H Anderson lt pha pdq com gt To r 390 mailman qth net Subject R 390 aligning an R 391 IF deck Hi folks I m doing an R 391 alignment 390 non A and hit a snag early on When tuning the coil on Z 501 there is no change in the diode load voltage _think_ my earlier steps are good enough but I m not sure notice that with my URM 25D the output frequency drifts fast enough that it is fairly difficult to find peak frequencies even just turning the frequency generator knob carefully enough while peaking on the 0 1KC bandwidth setting is challenging Is getting the coil not the cap on Z 501 sensitive to correct IF alignment prior to that point Everything else was peaking pretty easily though touchy due to URM 25 drift Is dumping the URM 25 and getting a better siggen a reasonable idea Will redoing caps and resistors stabilize it to any significant degree The drift is about 10 20 cycles minute downwards which is a pain when trying to align circuits trying to filter 100 cycles Thanks for any advice Paul Date Mon 29 Apr 2002 15 14 10 0400 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 aligning an R 391 IF deck T
271. e Tek 535 is a fine scope works pretty well even by today s standards and is a must have for boatanchor enthusiasts If it does nothing else with its half a kilowatt power consumption and big cooling fan it makes a good space heater Well Tek used a number of regulated supplies and all were based on the value of the 150 volt regulator Warning Do not adjust 150 unless you are prepared to realign the entire scope This was reason enough to delay the application of high voltage Drift of 150 supply and moving those other regulated voltages along with it and failure of a decoupling resistor or two is all the trouble I ve had with it over the past 15 years or so Use a DVM to set 150 and then the adjustment will be repeatable If you don t have silver solder for the ceramic terminal strips then cut leads close to defective part and then splice to replacement part lt snip gt From guido lt laffitte prtc net gt Date Tue 8 Jul 2003 23 54 47 0300 test gear page 28 Subject R 390 R390A test rig The OS8 U oscilloscope appears as part of the test setup in the original R390A manual with the URM 25D signal gen Upon working on several OS8 Us have found that the usual culprits in most malfunctions are the multiple section electrolytic caps of the power supply Replacing them brings back the little 3 scope as good as new Of course any paper caps especially in earlier models should be replaced but always go after those filters
272. e accessories that come with it are helpful and convenient fitted a slightly larger frequncy knob in the same style as the orginal with the added feature of a crank handle can whip that thing to its next frequency very quickly next located an HP 5328A counter not a vital piece of gear but couldn t resist the urge to acquire that toy with its bright red digital display and yet another toy A TS 505D U caps off the alignment gear roster it s the coolest VTVM ever made IMO For PTO end correction it s possible to hear its output on another receiver for getting a handle on how far off it is However the HP 5328A really shines for this chore though Alignment is fun now when get an evening free It s a pleasure to watch the TS 505D U s readings peak ever higher with each pass through the alignment steps Entry level gear should not prevent one from doing a respectable job Main thing is to have fun be patient learn and upgrade inexpensively when opportunities arise Date Thu 21 Jun 2001 09 39 30 0400 EDT From Paul H Anderson lt pha pdq com gt Subject Re R 390 Thanks and Restoration Update Just a quick FYI on the TS 505D U agree it is great Buyers should avoid the earlier TS 505 U however as it requires batteries and the one that got was test gear page 55 corroded beyond repair Not really worth fixing in my opinion The TS 505D U however I d consider restoring it is that nice Date Thu 2
273. e are loading the circuit with capacitance I1 am assuming you are using a X1 probe If you use a X10 scope probe bet it will not load the circuit The added capacitance is causing the oscillator to die it is not just DC loading that you are observing Date Mon 22 May 2000 10 00 02 0500 From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 Instruments It s a switchable probe and don t recall trying the X10 position I ll see what that does With the readings was getting being so small to start with didn t attempt the X10 position Date Mon 22 May 2000 09 00 09 0500 From Dr Gerald N Johnson lt geraldj ames net gt Subject Re R 390 Instruments The 10 1 Tek probe doesn t load things much but the direct probe does load quite a lot The raw scope input R is usually 1 megohm and then there s the coax from scope to probe tip Tek makes a special low C coax but its still probably 13 or 15 pf per foot Some Tek 10 1 probes do the division mostly in the box at the connector so have a lot of capacitance on the probe the better ones have a resistor shunted with a capacitor at the probe tip The attenuating scope probe has to be adjusted for the ratio of the capacitors across the series resistor 9 meghoms for the typical 10 1 probe and the shunt of the scope input both scope circuitry and cable to be the same as the resistive ratio That s what sets the HF attenuation And is tested by making a sq
274. e days when the bench is completely clear and have no other projects will do something about it Date Sun 10 Jun 2007 12 31 35 0400 From rbethman lt rbethman comcast net gt Subject R 390 attenuator IG 57A and Signal Generator purchased located the attenuator It is being sent purchased a Signal Generator All problems solved Now to clear backlog of repairs when THEY get here Date Sun 10 Jun 2007 13 07 12 0500 From Barry lt n4buq knology net gt Subject Re R 390 WTD AN URM 25 do the same thing with my GR1001A and its 2V output Handy especially when the output voltages on the generator aren t quite enough to drive the counter For the most part I m simply rocking the dial for maximum gain but sometimes do want to know closely where that frequency is Date Sun 10 Jun 2007 14 27 09 EDT From DJED1 aol com Subject Re R 390 WTD AN URM 25 see them sometimes at flea markets but you take your chances on whether they work or not haven t priced them because already have a Fair unit bought for 175 However took a look at ita year ago and wondered why was struggling with a 50 year old piece of test equipment that was hard to set to frequency and drifted quite a bit So I did a little searching on eBay and bought a HP8660A for 300 Wow what a difference in functionality got it with a 0 01 to 110 MHz plug in So now can use the thumbwheel switch to set the frequency t
275. e group and scored both 7 amp 9 pin test adapters and replica spline wrenches for my two R 390A s Haven t found a ready made octal socket test adapter yet other than Nebraska Surplus at an exhorbitant price anybody have an extra Ideally I d like to make some module extender cables Anybody know of a source for the required deck sockets and harness plugs Also what are the correct part numbers for the connectors and sockets I ve tried to search on the numbers in the Y2K manual and haven t found them on the net know there has to be a military or surplus connector supplier out there that has them Lastly one of the R390A s has had the electrolytics in the AF deck replaced They are mounted in octal base plug in relay housings One has the keyway broken off Anybody know of a source for these I ve looked at Mouser Newark Allied and Grainger with no luck Thanks in advance between the Y2K and Y3K beta manual The Pearls the Hollow State Archives and the feedback from this group I m finding I m able to get all my questions answered Date Sat 21 Feb 2009 14 59 35 0600 From Barry lt n4buq knology net gt Subject R 390 Leader Equipment Is Leader brand test gear any good Looking at an audio signal generator and wondering if the brand is reliable test gear page 188 Date Sat 21 Feb 2009 15 20 06 0600 From Grant Youngman lt nq5t tx rr com gt Subject Re R 390 Leader Equipment Over the years I ve used a v
276. e in PDF format somewhere Date Tue 26 Dec 2000 04 41 53 0600 test gear page 42 From Nolan Lee lt nlee gs verio net gt Subject R 390 Free TV 7 series tube tester settings file Yeah it s ready for public download after lots and lots of very tedious work The current version is beta 90 and yes there are some more things plan to add to it in the future feel confident that it s the single most comprehensive listing of settings data for the TV 7 series of military tube tester known to man Best of all it s free lt grin gt You can download it from the TV 7 page on my website at http www acadiacom net nlee Settings files are also available for the l 177 and TV 2 series of mil tube testers on their respective pages at my site Again for free Please take the time to actually read the TV 7 page before you download the beast Holler back if you spot any errors or have any reference material that wasn t included in the file Also I d appreciate it if any of you that have links to my site for the I 177 and TV 2 series data would update your description to include the TV 7 series My next project will be settings data for the TV 4 and TV 4A tube testers I m still looking to round out the info that have Holler if you have a TV 4 series and what if any documentation you have for it Date Mon 26 Oct 1998 23 06 44 0500 From Gary Kaufman lt gkaufman bu edu gt Subject R 390 Lytic cap replacement one more viewpoint I d s
277. e know if downloading them does not work can email them to you I d be glad to hear any tales you have about restoring your meters have at least one of them here and it s a fine meter A bit hard to read compared to some commercial meters with larger movements but all in all it s a fine meter test gear page 119 Date Sun 03 Apr 2005 07 53 02 0500 From Mahlon Haunschild lt mahlonhaunschild cox net gt Subject R 390 Speaking of TO 6As Was given a Sprague Tel Ohmike TO 6A yesterday Free was a good price in this case since all of the paper capacitors in the unit need to be replaced and also because the meter is blown and needs to be replaced Not unlike what went through with my Heathkit capacitor tester a while back the two standard paper capacitors in it were so leaky the bridge never balanced same thing is going on with the TO 6A Has anyone ever run across a calibration procedure for these Date Sun 03 Apr 2005 10 39 04 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 Speaking of TO 6As I m sure the marketing departments at each of the companies that made them had long lists of exactly why theirs was the best on the market From what have seen they basically are all balanced bridge instruments If you replace the standard capacitor in one of the arms the main issue is to hit the value correctly A reasonable way to do a quick check on any of these gizmos is to have a metal package tubular tefl
278. e of irregularities in a waveform is not immediate evidence of a failing crystal Either they don t work or they begin to lose output and ultimately don t work Unless the oscillator is tuned at the output for the crystal frequency and unless the oscillator is biased explicitly for that particular crystal and mode of operation there is very great likelihood that some harmonic energy is being generated by the oscillator Also some oscillator circuits are better at harmonic generation than others You would need a spectrum analyzer or a VHF UHF receiver to investigate this and the fact that some of your crystals do not exhibit the spike on a scope doesn t mean that significant energy isn t being produced at their harmonics The fact that this energy is being injected into a mixer mitigates the presence of any harmonics as the mixer itself is a harmonic generator They are sometimes referred to as a comb generator in the older literature In other words don t worry Is there sufficient amplitude Is it grossly distorted This begins to get off topic but there is ample and long standing evidence that a square wave with very fast edges is the best waveform to drive a mixer Such a waveform has quite high energy in the harmonics It is the relatively slow transition in the interval between either fully saturated ON or test gear page 75 fully cut OFF that promotes susceptibility to intermod Thus a fast square wave minimizes the susceptible time
279. e output as a 1 at an IF stage have gain The amount of gain can be worked out with a step attenuator Whether the sensitivity is 8 008 or 0008 is immaterial at HF because of atmospheric noise Date Sat 17 Aug 2002 14 45 57 0700 From shadow lt shadow gilroy com gt Subject R 390 about URM 25D Mod and Notes Dallas Lankford Hi Guys need some help and information have read questions about URM 25 D and from time to time and questions about the hollow state news letter article on this unit Even as late as last week When purchased and picked up my two 25 D today received a package of hand written notes and hand drawings from Dallas Lankford about the URM 25D Dated 11 88 and Rev 1 94 There are 26 pages of hand written notes My question is Has anyone scanned them before and posted them to a WEB site So the entire group can view them The notes are old and its hard for me to believe That someone has not posted the a site or scanned them So they can be email to someone that may need them I m thinking that they may be the same notes as in the hollow state news letter or maybe even the early version of them do not think the news letter used hand written notes But have tried to find the article before but no luck If the notes are needed then may scan them If not then I m not going to take the time So need some information and help Date Wed 21 Aug 2002 06 09 50 0700 Fro
280. e replacement is very tight and you can t really disassemble it too far You sort of disassemble it pull one side board out as best you can in order to get to those 4 caps Knowing your electronics background you should find it easy enough Anyway it is a splice job You need to replace C159 C160 C161 and C164 don t have the value of those caps as didn t write them down before installing them Can you call R J at Fair 419 227 6573 and ask him about the capacitors If not let me know and I ll call for you still have your address and will mail copies of my sheets to you All you need is the value of those 4 caps with locations Glad to see you around this motley crowd Your generosity and help has been greatly appreciated in the past I ll get those sheets copied and out to you Barry Williams Date Wed 19 Dec 2001 21 26 58 0500 From Bruce Ussery lt bruceussery hotmail com gt Subject Re R 390 URM 25D info My URM 25D manual W7FG copy says the 4 caps you mention were originally as follows C159 C164 01 uF 20 300V paper C160 C161 1000 pF 2 500V mica Which brings to mind the question What do you guys use to replace mica caps these days There is some basic troubleshooting info sounds like you re right on target as usual at http Awww qsl net k5bcq URM URM html Also side by side photos of the D and F models And sometime this year found and downloaded a nice compendium of URM 25 notes someone
281. e sack By being versatile we can be much more successful Date Fri 29 Jun 2007 00 44 31 0400 EDT From lt daveaust pol net gt Subject RE R 390 Tube testers Count me in as one of the wimps too but hell have a lot of fun call me crazy sitting around testing tubes on my mil testers while listen to my 390s like the heavy testers that give me a little exercise too The TV 2 parts supply is dwindling in terms of original meters tv 7s too and the TV 2 trannys as well Replacement meters are available but not too cheap Otherwise you can usually get them going once you eventually find the parts agree with needing test gear page 155 an out of circuit prelim screening for tube quality before jamming a shorted tube into the radio etc as well as it being nice to just sort out the better tubes of the bunch when slightly lower Gm tubes will still work great in these rigs Date Wed 18 Jul 2007 09 17 39 0400 From Roger Gibboni lt rgibboni Imdulye com gt Subject R 390 TV 2 tube tester OK wimped out and bought a TV 2 After a little work it runs great I ll tell you it s very nice to be able to optimize the 390 performance by selecting the tubes for highest transconductance Does anyone know where to find updated tube test data for newer tubes It would seem that with the versatility of the TV 2 you should be able to set up test parameters for any tube that fits in a socket Date Tue 24 Jul 2007 20 11 56 0400
282. e secondary winding it just keeps flipping from O to OL reading when trying to read the secondary resistance On the primary which is lower inductance it flips once or twice then stabilizes on the correct 400 ohm resistance reading As mentioned had no problem reading this with my BK average quality non autoranging meter and checked it with the 4 meter test gear page 107 bought from Harbor Freight which of course is not autoranging The guy sent the transformer to was using a Fluke meter on autoranging which was the start of this escapade The moral never send in a man to do a boys job and of course if you have a Harbor Freight model you can send ina baby And the Fluke can be trained for the job by turning off the autoranging Thanks for the comments far as know there are no inductances in a 390a that are large enough to cause this problem But have only a smattering of knowledge about the various ways that today s exotic meters perform all their magic Dan Date Wed 14 Jul 2004 20 16 09 0500 From Bill Hawkins lt bill iaxs net gt Subject RE R 390 DMM bounce If all you wanted was the DC resistance of the secondary and all you had was an autoranging DMM could you short the primary to calm down the autoranger Date Wed 14 Jul 2004 19 54 37 0700 From Dan Merz lt djmerz 3 cities com gt Subject Re R 390 DMM bounce Hi Bill now why didn t think of that Z transformation or short circuit r
283. e stiff detents test gear page 98 Love my 8640B Date Sat 07 Feb 2004 08 49 00 0800 From Leigh Sedgwick lt bipi comcast net gt Subject R 390 Advice Proper Use of Meggers recently picked up a megger but honestly don t know much about them They are apparently great for checking leakage through caps which is the main reason bought it For the record it is a old Navy unit made by Winslow Teletronics Inc Model ZM 63 PSM 35 with a Navy designation of AN PSM 35 It measures Megohms resistance at 500V notice that can vary the output voltage by rotating the crank at a slower speed but the readings fluctuate So take it that the proper use requires rotating the crank at normal speed and full voltage output While 500V is fine for some caps it typically exceeds some of the smaller caps found in receiver boat anchor receivers So does one need a smaller unit for lower voltage caps to get reliable readings Sorry for my ignorance on the subject I ve just never used one of these Can someone shed some light on this subject for me or point me at a reference for their proper use Any manuals available for this animal BTW just finished tearing apart my RF deck and cleaning all the gears found that even a clean looking unit like mine was before started should be rebuilt many gears were stuck together from hardening of the lubrication oil even though they looked quite good to the naked eye I m looking forward to exp
284. e the taxpayer s money At that time if you opened the box on a new tube it was a good bet the tube was good Now it s a mixed bag Also nowadays most of us are trying to optimize performance not operate marginally But there are some other considerations suppose the manly way to check a new old stock or used rectifier tube is by plugging it into the circuit Before you get the voltmeter test prods out after having pulled the chassis or module if the filter caps sizzle and explode or the power transformer burns out that particular tube is shorted No problem just try another after replacing the caps and or transformer OK maybe it s an audio tube ditto for the audio transformer IF If it burns out one or more of the IF transformers begin again from step 1 after replacing the transformers Yes one consideration is that this is not 1947 or 1957 any more Fifty sixty years later we re gradually learning a bit more about the long term shelf life of NOS tubes They have often been shipped around repeatedly and subject to vibration and possible physical shock damage haven t found many but enough shorted ones which were screened out by my tube testers to be worth a quick test I d rather use a tube tester to find out than an unobtanium power or audio or IF transformer Then even if not shorted an NOS or used tube might be substantially weak or gassy Who was that guy with the sig line They don t make tubes like
285. e them on your R39 series radios have one and some time ago noticed the AC probe stopped working Normally after an hour or so the probe will become warm due to the rectifier tube s filament and mine had stopped warming up Figuring the diode in the AC probe had died recently started looking for a replacement diode As many of you also know these tubes are becoming quite expensive Knowing this decided to check everything out as the tube itself may not really be the problem Some of the meters use a 2 01C diode some use an EA53 and others may have a probe where either type can be used there are supposedly slight physical differences between the two tubes making them not completely interchangeable Mine has an EA53 and checked the specs for it noticed that the 2 01C uses a 5 0VAC filament while the EA53 runs on 6 3VAC Checking in my manual it states to set the filament voltage to 5 0VAC and that was what did when went through it a few years ago A little reading on the internet reveals that if your meter uses an EA53 you should set the heater voltage to 6 3VAC not 5 0VAC and some manuals may even make mention of this mine does not There is a variable resistor used with a ballast tube to set the heater voltage set the heater voltage at the probe to 6 3VAC and reinserted the EA53 let it warm up for about an hour and sure enough the probe began to warm up test gear page 132 again It is again working in the A
286. e to calibrate it Like all military gear there s a manual somewhere that tells you more than you would ever want to know about how to do it The same thing applies to stuff like TV 7 tube testers We all my self very much included seem to overlook this little chore all to often Date Sun 9 Jan 2005 21 42 46 0500 test gear page 346 From lt pdulaff earthlink net gt Subject Re R 390 Servicing Advice on Signal Generator URM 25D Thanks for the input have it on the bench now It is very well built There aren t any black beauty caps in this thing They use metal tubular decoupling caps that is flange mounted with a glass seal for the terminals Resistors look like new but will check them for increase in value The RF choke that shorted to ground looks like the plastic terminal that holds the end of the wire had cold flowed over the last 40 years and changed shape enough that the terminal contacted the ferrite core of the choke and shorted that side of the choke to ground have the manual for the unit and was studying it since figured had better check both frequency and signal output calibration after get it back together Another thing to consider on these units is lubricating the worm gear for the turret drive Works OK but the grease is all dried out Date Mon 10 Jan 2005 08 08 04 0600 From Dallas Lankford lt dallas bayou com gt Subject Re R 390 Servicing Advice on Signal Generator URM 25D Sure Let
287. eactance In either case the input impedance is going to be lower I tried it with the transformer in question and the pocket autoranging meter it took 6 bounces before settling on the correct reading of 1500 ohms on the secondary You have won my respect for thinking of trying that Since it took 6 bounces suppose there is probably a meter out that wouldn t work with that solution if it has a faster autoranging rate but then that would depend on how the particular meter sends current through the transformer to make a reading each time it does its autoranging routine like your idea thanks for a great idea to try and it worked with the autoranging meter have one of those small toothbrush case RS models of about 7 years back Dan Date Fri 23 Jul 2004 18 35 01 0500 From Harry Joel lt hcjoel direcpc com gt Subject R 390 Manual For Fluke Hello don t know if a Fluke Model 335A DC Voltage Standard Differential VM would be usefule for some measurements on BA s have acquired one cheap at an auction Does any list member either have or knows where to get a manual have checked BAMA he does not list it Date Fri 23 Jul 2004 21 42 55 0400 test gear page 108 From Bob Camp lt ham cq nu gt Subject Re R 390 Manual For Fluke There seem to be a ton of these showing up right now I m not real sure who is dumping them but I ll bet it s the government Needless to say picked up something similar The neat thing abo
288. eak then when the center of the peak is found the needle will sometimes go off the scale I ve found some peaks on the R 390A to be shallow and wide and others to be very narrow and high and some can t be found until something else is peaked first So if the receiver is way off it may take some hunting test gear page 46 Date Sat 20 May 2000 18 43 31 0500 From Dr Gerald N Johnson lt geraldj ames net gt Subject Re R 390 Instruments The Simpson 269 doesn t load circuit much but every one I ve used was slow as molasses in Canada in January Extremely over damped which means you wait several seconds for it to ooze to a reading and that slowness makes finding alignment peaks really tough have a couple in pieces think enough pieces to assemble a working one but I m in no hurry to do that For VOMs prefer the 260 anyway And for most VTVM applications use my Tek scope Date Mon 22 May 2000 08 38 49 0500 From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 Instruments Odd that you should mention this Over the weekend made a strange discovery After replacing some fried resistors in my HP410B when went to use it on my R390A it no longer worked set it aside for lack of time to fool with it Well got around to fixing it this weekend just a loose wire from the PC board As many of you remember I ve been complaining about low output from my crystal oscillator deck When got the HP fi
289. ear Maybe I ll finish it this year lt grin gt While you have the URM 25D apart measure the values of all of the resistors that you can get to Make sure that you check resistors in the modulation meter circuit If R167 R168 R170 or R171 have drifted upwards more than 5 from their marked values replace them Also check R169 the meter calibration pot for the modulation meter function It s a 2500 ohm carbon pot If it measures much more than 2500 ohms between terminals 1 and 3 replace it too There are some other potential problems that can cause some hair pulling when you attempt to calibrate the RF voltmeter function Check R129 the 100 ohm resistor that one end of is soldered to the back end of the 200K front panel BNC connector It s probably out of spec from being soldered and unsoldered a few times Since the 200X jack is used to set the output levels during the calibration procedure you want R129 to be as close to 100 ohms as possible If you have one that is slightly lower in value like 99 ohms use that one as a replacement By the time it s soldered into place it ll probably be 100 ohms Also check the value of R130 the 500 ohm resistor that feeds the input of the attenuator It s a film type resistor located on the buffer amplifier subassembly It test gear page 286 should be 495 to 505 ohms max It s another negative temp coefficient resistor so if it out of spec you ll have to do some searching to find one If
290. ear page 384 don t understand how the radio leaking RF determines whether a leaking generator will get into the radio understand that a leaking generator can get into the radio but don t see what the radio leaking has to do with it Is it because if the radio leaks then there s a path for RF in either direction Sorry but the way that s worded it just doesn t quite make sense to me Date Thu 1 Mar 2012 21 06 26 0600 From lt wb5uom hughes net gt Subject Re R 390 AN URM 25s could use some help understanding this too Im just a lowly radio tech Date Thu 1 Mar 2012 20 34 46 0800 From Dennis Wade lt sacramento cyclist gmail com gt Subject Re R 390 AN URM 25s think by the radio leaking he means that the radio will pick up be sensitive to signals coming in through paths other than the antenna connector antenna circuit Date Fri 2 Mar 2012 08 13 11 0600 From chacuff lt chacuff cableone net gt Subject Re R 390 AN URM 25s If the radio is so designed that RF can get out of various stages to the outside world those same weaknesses that allow the rf out will also allow RF in If your signal generator cable is leaking RF it becomes a significant local RF source You may have the internal attenuator set to 001uv but you have a high level of RF going into that attenuator and if it s leaking to the outside world before being attenuated at some point you reached a point where the radio was detecting the leaka
291. ecification Most of these seem to get used in high impedance circuits where you will notice the effect though test gear page 348 Date Tue 11 Jan 2005 11 18 38 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 Servicing Advice on Signal Generator URM 25D gt change as a preventative maintenance item All the resistors and capacitors in the Twin Tee audio oscillator circuit All other paper capacitors You really should have the Dallas Lankford 18 page document gt URM 25D Overhaul Notes by Dallas Lankford 11 88 revised 1 94 with copy gt of HSN Supplement from Issue 41 about the Terminal Board The Overhaul gt Notes themselves did not appear in HSN only a notice that they were gt available separately There are about 18 pages if remember gt correctly Dallas has not made a similar set of notes for the F model gt unfortunately You can get a copy from the editors of Hollow State News for a modest sum It will be the best modest sum you have ever spent if you intend to keep your URM 25D running indefinitely monn nnn nnn nnn a nnn nnn nn nnn nnn nnn nnn nnn nnn nnn nnn nnn nnn nnn nnn nnn nnn nn nnn nnn nnn Date Tue 18 Jan 2005 00 26 32 0600 From Tom Norris lt r390a bellsouth net gt Subject R 390 HP 606 vs URM 25 I ve had a URM 25D for years and have never had any problems ran across an HP 606A recently and it s in the process of being shipped I ve never used a 606 though
292. ecimal places when working on this equipment The same goes for a signal generator The URM 25 is robust rugged complete with accessories has built in modulation sources and like all tube equipment rarely fails realize that some of my loyalty comes from having used this the URM 25 and other such equipment in the Navy back in the day and finding it absolutely reliable but that is the truth It is reliable and again is what the manual and most likely the manufacturers calibration and test department used when the 390 s were shiny and new lt rant gt lt venting gt also carry this same theme through my other test equipment My scope is hollow state have an L C R bridge which is also hollow state and a frequency counter similarly hollow state Although have a full stable of up to date state of the art wnoop de do computerized equipment still enjoy using the older equipment because frankly enjoy using it and enjoy the sights sounds and smells from hot vacuum and the deposits of many years of cigarette tar on various items Although no longer smoke it brings back memories of far better times when one was allowed to indulge ones pleasure without shrilly screaming soccer moms telling me what should and shouldn t do also enjoy remembering the era when we did actually have a test gear page 81 manufacturing base here in the good old US of A and electronics people were a sought after commodity lt ra
293. ect Re R 390 Signal generator connection questions Can I give you my way to do it if you have a 455 000 khz Xal connect one side of it to the URM 25 D I use a scope probe and the other side of the Xal to the tip end of your scope probe The 2 free ground leads together You might have to apply as much as the full 100 000 uv output depending on the sensitivity of your scope you will find the 455khz signal on the output of the xal as you tune the generator around the freq Date Mon 10 Jan 2000 05 08 26 0600 From Nolan Lee lt nlee gs verio net gt Subject R 390 Sig gen for checking crystals gt Can give you my way to do it if you have a 455 000 khz Xal Pretty slick bubba If you were local I d buy you a bottle of beer Just for kicks fired up the 25F and the old Tek 547 and one of the counters and tried this to check thru some 200 KHz calibrator crystals that had set on the side to be sorted test gear page 294 out for dead and off frequency ones at a later date weeded out the dead ones pretty quick and with a hell of a lot less effort than having to install them in the R390A All of the ones that worked would easily oscillate at 400 to 600 uv levels The dead ones were deader than a hammer even at 100 000 uv volts Now how practical would it be to throw together a little crystal test chassis for determining the actual frequency of the crystals Nothing real complicated Say a 6
294. ect Re R 390 grid current can check that tried swapping it with another with the same results however both are most likely the same age used under much the same conditions so both could be gassy Date Mon 13 Jul 2009 08 49 42 0400 From Shoppa Tim lt tshoppa wmata com gt Subject Re R 390 eBay Funny of the Week Once in trying to build a VFO managed to get the 6AH6 to squegg It was producing no less than 3 distinct frequencies in very complicated waveforms 1 The desired oscillation on the desired frequency 3 5 MHz would start to build up test gear page 202 2 A UHF parasitic near 400MHz would kick in as the 3 5MHz waveform built up and quench the oscillation 3 Above cycle would repeat with a rep rate in the low kHz Why the handbook recommended a hard to stabilize UHF tube for use as a HF VFO I never understood think it was there that learned that mere specsmanship looking up the tube with the most and highest in the tables often does not produce a working design lt snip gt Date Mon 20 Jul 2009 16 44 07 0500 From Barry lt n4buq knology net gt Subject R 390 OT Problem with HP 606A linearity I ve been working on an HP 606A for a while and have come up on something don t know how to correct The linearity is not good The specs say this thing should be within 1 but I m not getting that could get the endpoints on target but as the frequency went from lowest to hi
295. ed as much as some I ve seen Still thinking about how want to make that fix before they get worse Good luck with the FM board There are a lot of individual boards on eBay but they re pretty high in price and no guarantees Date Fri 11 Feb 2011 14 30 27 0500 EST From frankshughes aim com Subject Re R 390 R 390 Digest Vol 82 Issue 14 http groups yahoo com group hp_agilent_equipment Is a good place to get help and advice from other HP owners ordered some of the 8640B gears that the guy in Italy casts just to see what turns up Mine aren t cracked now but having spares insures that they never will fail especially if they are stored where the 8640B can see them Date Wed 16 Feb 2011 19 20 11 0500 From Michael W1RC lt subs wirc net gt Subject R 390 FS USM 3A including TV 4A U Tube Tester and TS 673 U Signal Tracer test gear page 243 Found this treasure in the basement This is an incomplete US Navy USM 3A Test set The USM 3A is a complete miniaturized service kit for tube type equipment and was designed for use in the field to troubleshoot and make temporary repairs to equipment The whole thing fits into a 1 cubic foot metal case the CY703A U The TV 4A U is a compact tube tester made by Weston and does a remarkable job of testing tubes for its size Also included is the TS 673 U signal tracer and is complete with the neat metal box containing the probes and the little headset
296. ed micas and a couple of the oil filled paper caps and even the big oil filled B filter cap but generally it s the caps listed above that cause the majority of the problems Also if you run into problems calibrating the modulation or signal level aspects of the meter drop me a note There are a couple of tricks for doing this providing that your meter is OK Date Sun 23 Jan 2000 19 45 51 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 SG 103 URM25F Question gt With my C the modulation just dropped out but if switched it in and gt out again it came back for a while Not a very common model gt While the higher letter models seem to be more desirable they do not necessarily indicate improvements in all respects and capacitor situation seems to cut across them all test gear page 300 The early URM 25 25A 25B I think the B models were designed to be used with 53 5 ohm terminations coax etc They used an entirely different bunch of adapter cans In addition they didn t have the internal calibrator until the 25B model I m not sure of the output impedance of the 25C model Date Mon 24 Jan 2000 15 00 05 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 SG 103 URM25F Question gt Concur re the value of the URM25F and agree with you that it is a lot easier to Yep there s no comparison Some of the caps like the 0 47 s at 600 volts are a little more expen
297. ed thoroughly and reinstalled to set the radio on the 7 999 marks to crank about 100 mV of RF in the antenna and hear a week signal The radio is responsible for that part The story here is use what works for each of you We all have preferences there is no right or wrong equipment my 2 cents worth Date Sun 15 Feb 2009 15 19 53 0500 test gear page 184 From Jon Schlegel lt ews265 rochester rr com gt Subject Re R 390 test equipment question guess don t see the newer stuff as what you need but rather as tending to make the job easier if it happens to be available As always tradeoffs are involved Date Sun 15 Feb 2009 15 37 14 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 test equipment question Tom You have hit it on the head The newer equipment may well make it easier and quicker However don t get paid by the hour to work on MY radios So IF need to let things warm up for a bit longer The R 390A HAS to warm up so that IT has quit drifting can let the URM 25 simmer also Those that work on this older gear use what WE desire and what WE have have just as much fun keeping the test gear running well as do the R 390A and SP 600 Date Sun 15 Feb 2009 18 38 02 0500 From David C Hallam lt dhallam rapidsys com gt Subject Re R 390 test equipment question OK will extend this thread need a sweep generator would like to have a HP 8601A but they
298. ed with entirely different user communities in mind do know people who use their radios as spectrum analyzers And also know people who use their spectrum analyzers as radios But IMHO this is far from optimal reminds me of using a butter knife as a screwdriver and a screwdriver for a butter knife One issue is that superhet radios really have a dynamic range at the IF level of maybe 30 dB before they test gear page 226 really begin compromising performance That s not too bad ifyou re using it as a radio and is why superhets almost universally have AGC But it sucks if you re using it for many purposes as a spectrum analyzer Date Fri 06 Aug 2010 09 28 57 0500 From Barry Williams lt ba williams charter net gt Subject Re R 390 HP spectrum analyzer question The Heath SB 620 works well and is usually around 100 when you can find them You are limited to a smaller range when using 455kHz and can t remember it now Maybe 500 kHz p s I m also using a HP 3586B as a receiver Date Thu 12 Aug 2010 21 28 18 0700 PDT From Perry Sandeen lt sandeenpa yahoo com gt Subject R 390 HP Spectrum Analyzer A HP 3585A is certainly the way to go if one has a spare kilo buck In the more affordable range is the HP 141 series They are plentiful and can be found complete and working in the 400 range But shipping can be high There are a number of others you might also want to consider The HP 181 while not as prevalent as the
299. edance ratios for transformers while the TO 6 does not prefer the TO 5 Date Sat 20 May 2006 17 09 16 0500 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 Capacitor Analyzers Do either test the caps at rated voltage I m not familiar with them I m using a Sencore LC 73 Date Sat 20 May 2006 17 15 28 0500 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 Capacitor Analyzers Well got the model wrong it s an LC 102 The model was thinking of that had in the past was the LC 53 which is cheaper and works great Several on the auction site Date Sat 20 May 2006 17 07 24 0700 From Craig C Heaton lt wd8kdg worldnet att net gt Subject RE R 390 Capacitor Analyzers The TO 6A will test the caps at rated voltage Date Sat 27 May 2006 21 36 27 0400 From Scott Bauer lt odyslim comcast net gt Subject R 390 off topic sorry am sorry for the off topic post have lost all of my email addresses was told there is a gentleman in Frederick MD that does wonderful work on tube testers Mine needs some attention but my hands are too shaky so solder in those tight spaces Does anybody know who he may be Sorry for the bandwidth Scott Date Sat 27 May 2006 21 42 19 0400 From Ron Hunsicker lt ronhunsi ptd net gt test gear page 141 Subject R 390 Tube Tester Guy have an e mail from 2001 from Bill Waters at lt wate erols com gt Also an address 5016 Mt
300. efer to them as valve jockeys the large government department where trained did have a tube tester in the lab and used to sample tubes from the manufacturer to check they were in specification when you look at the original specification for a radio like the RCA AR88 it called for full performance from the radio if ANY or ALL of the TUBES were down to 30 EMISSION the reality is that well engineered equipment doesn t make great demands on the tubes Our family acquired a television set in 1956 it had 23 tubes by 1970 most of the tubes were original the only tubes that had been replaced were the horizontal O P damper diode eht rectifier Ht rectifier and a double triode in the cascade amp in the tuner the monochrome picture tube also was at the end of its life lots of people these days have the idea that tubes are consumable items that need replacing every so often i often here people talking about re tubing their rig what a consummate waste of parts and time Regards to every one hope this is of interest Date Sun 7 Aug 2005 02 00 00 0600 test gear page 126 From Kenneth Arthur Crips lt CRIPSO1 MSN COM gt Subject Re R 390 tube testers gt have always been of the opinion that the best tube tester is the circuit that the tube is in This is a good point have a Sylvania tube tester and it works ok but there are times wonder just how accurate it is found my tube pin straighter now am going to look fo
301. el 177 VTVM test gear page 407 have one of those as well and no manual have searched everywhere can think of and haven t found one If someone should send a source to you offline would you share it think it would be a very nice VTVM to use with boatanchors too Date Sun 24 Mar 2013 07 47 56 0600 From Anthony Casorso lt canthony15 msn com gt Subject Re R 390 B amp K Dynascan Model 177 VTVM A Quick check with Google and spotted a manual with schematic in PDF frmat http radiorestorer com bk177v 95 PDF Date Sun 24 Mar 2013 18 21 45 0700 PDT From Perry Sandeen lt sandeenpa yahoo com gt Subject R 390 HP 3586 Problem was checking out two operational HP 3586B s which normally use for RF work on the lower frequencies and found out one would not sync below 300 KHz or so and the other below 200 KHz on the Fo rear output connector So contacted my friend Mike Fisch and asked him to do the same test and his Fo output would not sync below 1 MHz So my questions to the list are 1 Do other owners of HP 3586 units have the same problem 2 And if one had had that problem were they able to fix it and if so how don t want to touch the insides of mine until have more information Date Sun 24 Mar 2013 21 41 50 0400 From Bob Camp lt ham kb8tq com gt Subject Re R 390 HP 3586 Problem Haven t had the problem on the 3586 but have had it on similar HP gear Typically it s the VCO that no
302. elieve in a tube checker as a MECHANICAL check not a performance check figure if the cathode has enough emission and all the elements are connected their pins and not shorted together its going to have the gain can t conceive of a common failure of a tube that can cause a loss of gain that wouldn t lead to a short suppose the grid wire could break but if it isn t continuos and its supported by a sturdy wire cage its likely going to flop to the cathode or screen So use the old emission tester as my fundamental test and watch for grid current with the grid emission tester With the emission tester check for open elements and for shorts Most often a tube fails from wearing out the cathode emission or shorting heater to cathode or getting gassy All these may affect gm reading on a transconductance tester but only incidentally by changing the available plate current Sure the gain will check low if the plate current is way down but the gain wasn t low the plate current was way down so the indication is false With lo plate current the tube couldn t develop the voltage swing on the output load that was expected But if the tube is low on emission and the transconductance tester doesn t use as much plate current as the operating plate current it can miss the problem Sometimes really bad tube noise such as intermittent open elements bad welds can show up in the tester by tapping on the tube while testing for shorts opens and
303. ell for Keep your eyes open for a good clean working TV 7D If you find one priced reasonable scoop it Lately a lot of the ones I ve seen are really beat to hell with serious dents in the case If it got hit hard enough or dropped from enough height to distort the case like that there s the change that the meter movement s life has been either shortened or terminated There s also a good chance that a switch sections or two can be damaged You haven t lived until you changed a letter switch in one If you don t luck into a TV 7D and happen to find something like an Eico 667 or something and it s cheap and in good shape scoop it No tube tester is really what you d call 100 I m sure that almost everyone here in the list that s used tube testers for any length of time will agree with me that they d had that tested weak bad and worked just fine in the radio etc The same goes for tubes that tested good but were deader than a hammer in the radios etc guess that you could equate a tube tester to the fuel gauge in your truck or your automobile if you re a not true redneck If you re pulling out onto the road and you look at the gauge and it indicates full it doesn t necessarily mean that you re going to arrive at your destination The gauge could simply be wrong the engine could sling a rod overheat you could puke a fuel pump you could wring the teeth off of a planetary set in the transmission or any one of dozens of other things
304. elow their series resonant frequency can often produce a much greater impedance and so in that frequency range a greater filtering effect providing the chokes are well shielded and the bypass capacitors have low inductance such as feed throughs The wire with ferrite bead has lower DC resistance than the RF choke Castings like any other metal work need to be annealed to keep them from warping Some ferrites are good insulators some are conductive The only way to be sure is with an ohmmeter Date Wed 20 Dec 2000 08 06 50 EST From Llgpt aol com Subject R 390 URM 25D Stability test gear page 322 Monday evening when got home from work turned my URM 25D on in prepartion for an IF alignment on a John R Leary SP 600 Did it yesterday evening in approximately 26 1 2 hourss it had drifted 1200 cycles hertz for the younger guys Not bad for a vintage piece of test equipment Date Sun 21 Jan 2001 22 10 58 0500 From Al Solway lt beral videotron ca gt Subject Re R 390 IF Gain Adj Pot R519 Walter built the 50 to 120 Ohm matching pad you describe on your R 390A Restoration site Much appreciated My URM 25F O P was calibrated using the procedure describe in the manual It was about 2 3V at 100Khz prior to adjustment Used a HP410C as the V standard Adjusted to 2 0V at J101 The open circuit O P at the RF Output 100 000uV attenuator position is 0 18V which is close to what it should be also checked the
305. ement short of a new one from Tek which was hundreds of dollars back then Make sure that if you re going to buy one it comes with the cable and attenuator You need to watch some of the older Tek gear that used lots of large selenium rectifiers in the regulated power supplies don t remember the 190A s having them so you should be OK with the 190B It s been a long time so you might want to verify it before you buy one My 50 MHz Tek 180A time mark generator has them The filter caps are in good shape the power transformer primary taps are correct for my line voltage keep the cooling fan and filter serviced and the rectifiers run real cool so haven t gotten around to replacing them managed to find a copy the Tek service bulletin on converting the 180A to SS rectifiers and picked up the dropping resistors and stuff that I ll need to do the conversion but just haven t gotten around to doing it Date Wed 15 Mar 2000 22 38 14 0600 From Jerry G Kincade lt w5kp swbell net gt Subject Re R 390 frequency counter Re picking out a freq from many others AND simultaneously accurately measuring its level without owning a spectrum analyzer was the lucky finder of a couple of nice condition working HP 312B Frequency Selective Voltmeters recently I m embarassed to say paid 10 each for them test gear page 34 from a surplus computer dealer who didn t know what they were in all fairness to me neither of us knew if they
306. ency The simple test for this is to push and pull on the frequency set knob while listening to the generator with a receiver set for CW The note should not vary much at all especially on the lower frequencies and when you let loose of the knob the note should return pretty much to what it was If the beat note disappears altogether or varies a lot your shaft has end play My notes include an email from a fellow who found a tension device that holds the worm gear part of that shaft in mesh with the gear that s on the tuning cap shaft He solved backlash apparently by adjusting that tension It s not clear that we are talking about the same thing or not do know that the F model has a different drive shaft mechanical arrangement would expect to see grease at the worm and main gear To fix this run the generator out of its case till it s plenty warm This makes sure your adjustments will not be thrown off due to warm up If you care to clean and re lube the whole frequency set mechanism first Then loosen the lock nut and turn the inner bearing seat in a bit and tighten the nut You ll have to learn how to preload the adjustment or allow for the effect of the lock nut tension after you make a change You should arrive at a point where the shaft has no perceptable end play and runs free both If there s a separate adjustment that sets the depth of engagement of the orm gear in the main tuning gear that is phenolic think then set that
307. epartment of the Army Technical Bulletin TG SIG 319 describing the use and schematic diagrams of the items in the kit The kit has four dummy loads and connectors for connecting the dummy loads to receivers under test Date Sun 3 Sep 2006 13 07 40 0400 From David C Hallam lt dhallam rapidsys com gt Subject R 390 DA 121A U Error in Post The correct number of the publication for Electronic Equipment Maintenance Kit MK 288 URM is TB SIG 319 not TG SIG 319 as put in my post test gear page 360 Date Tue 28 Nov 2006 17 02 03 0600 From Tom Norris Subject R 390 Differences between the various URM 25 generators I ve seen the F model with the flat panel and have a Trad SG 25 witha brushed metal front but otherwise appears to be identical to the B The one manual downloaded from LOGSA ages ago says it s for the URM 25B but the unit in the manual bears little resemblance other than general circuit description What other variations were there Date Tue 28 Nov 2006 17 22 15 0600 From Tom Norris Subject R 390 Differences between the various URM 25 generators Typo the generator have looks like a D not a B OOPS I ve forgotten my alphabet quite a bit recently Date Tue 28 Nov 2006 21 41 00 EST From Flowertime01 wmconnect com Subject Re R 390 Differences between the various URM 25 generators hope you get a nice long response to your question with more knowledge than have There we
308. er model one to work just gave up on the trade Date Mon 25 Jun 2007 21 25 03 0400 From Tracy Fort lt beerbarrel cox net gt Subject RE R 390 Tube testers Hmmm would say that it would be his loss Mine works great Of course mine is the later c u model found it very easy to work on So easy in fact that wonder why someone would actually pay someone to repair one Tube testers in general seem to be a walk in the park to repair compared to a 390 test gear page 148 Date Mon 25 Jun 2007 23 52 57 0400 From Scott Bauer lt odyslim comcast net gt Subject Re R 390 Tube testers Yes tube testers are a walk in the park The problem is when one needs a part it is usually the person that works on them So why not let him do it spend way too much time working on my collection of R 390xx as it is Oh BTW Roger have a TV 7 DU am very happy with it as it has never failed me It is a little tight inside had to change a tube socket and it was tough was told by Chris Haedt another tester guru SK a few years ago to try and find one of three testers A Heath TT1A A triplett 3444A or a B amp K 747B The reason is the newer mutual conductance circuit design Heath and WEston are practically the same tester They are both owned by Daystrom so you could also look for a Weston 981 Date Mon 25 Jun 2007 21 15 53 0700 From Kenneth G Gordon lt kgordon2006 verizon net gt Subject Re R 390 Tube testers
309. ercial entities is HP Model 11042A Coupler gt gt The 11042A has a pair of Type N connectors one each male and female gt allowing for in line insertion between a transmitter or RF amplifier and gt load The 410 series meter AC probe is used with the coupler by gt unscrewing the probe tip and then carefully inserting the probe into the gt special socket on the coupler Those of you who have the 410 meters and gt AC probe will note that there are a pair of small screw heads that protrude gt from the side of the probe body Those screw heads are used as the gt grounding and locking mechanism for the probe when it is installed in the gt coupler It is sort of like a giant BNC connector arrangement because the gt action to insert the probe is a push twist lock sequence The coupler has gt a special capacitor installed on a section of air dielectric transmisison gt line and the probe contacts that capacitor when properly seated gt gt have a downloaded copy of the military manual for the 410 meters That gt manual also refers to a neat accessory that have never seen it is the gt Model 11043A Probe N Connector There is no photo of it but from the gt description get the impression that this is a device that connects to gt the end of the 410 s AC probe probably also by unthreading the existing gt probe tip and replaces the stiff wire tip with a Type N connector If gt anyone on the li
310. eriencing the smooth action of an R 390A Hey thanks all 73 de Mike K7PI Mercer Island WA Date Sat 07 Feb 2004 11 56 50 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 Advice Proper Use of Meggers These are used normally to test high voltage cables transformers and generator windings don t believe that testing capacitors is recommended Date Sat 7 Feb 2004 13 48 29 0800 PST From lt jlap1939 yahoo com gt Subject R 390 Anritsu Friends In speaking of the best one more time We know the test gear but has anyone ever operated the early 50 s back to post war rec by Anritsu Have a family friend who still speaks English poorly that was the enemy in test gear page 99 the early 40 s tho he is just a few years older than me and he insists the mil equip around 45 52 was as good as could be had He came to this country in 55 at age 22 He was a japanese el engineer and continued in America As the modern equip is so good wonder about the radios From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 Advice Proper Use of Meggers Date Sat 7 Feb 2004 17 26 39 0600 The use of a hand cranked meggar was outlined in one of Chuck Rippel s videos on radio restoration can t remember if it was the SP 600 video or the R 390 not important It worked very well Don t remember the specifics Date Sat 7 Feb 2004 18 32 41 0500 EST From lt
311. es Updates have been made to my TV 3 TV 10 page at http www acadiacom net nlee Well I ve got a thousand lines of settings data typed in so far and am only up into the 6Exx numbers This is going to be one hell of a list of settings data for the TV 3 and TV 10 testers when it s finished I ve also added some info on some modifications including the meter protection modification that it well worth doing to your TV 2 TV 7 I 177 etc Cheap and it greatly decreases the odds of frying a meter movement The contract number list for the TV3 and TV 10 series is shaping up but still need additional information as far as high and low serial numbers Also I m still in need of any published settings data for the TV 3 or TV 10 dated later than May of 1966 Date Wed 5 Dec 2001 02 14 04 0800 PST From MICHAEL OBRIEN lt mikobrien excite com gt Subject R 390 tv 7 u problem and ca 4 tube data lt snip gt Now for the problems on my tv 7 u when do the range check b to c the meter goes off scale past 120 also on some tubes 6v6 6L6 etc on range C any ideas Does any one have a copy of setup and tube data for the hickok ca 4 adapter to be used with the hickok model 600 tester Ihave the model 800 data sheets for the ca 4 Does anyone know if the data is the same between the 600 and 800 Date Wed 5 Dec 2001 08 20 00 0800 From David Wise lt David_Wise phoenix com gt Subject RE R 390 tv 7 u problem and ca 4 tube data gt
312. es Then the 24xx analog series came along and I ve lost track since The prices in the catalogs cause my eyes to glaze over and figure I d rather have a truck than a scope for the same price Or a house for the price of a spectrum analyzer guess continue to dream As for range switching rings know the 465 485 had them probably the 5000 and 7000 families too But not the 45x 56x 53x or 54x Date Fri 26 May 2000 21 24 18 0700 From Larry Shorthill lt rfssi shorthill mindspring com gt Subject Re R 390 probes Check out the Tek website They should have probes listed in their accessories list am willing to bet that the current listing of probes costs more than what you paid for your old scope But they will work for you on your old scope just fine Tek had a whole division making probes and accessories for their instruments test gear page 11 There is a lot more in them than you would first believe For one thing a probe and it s connected instrument should not disturb the circuit under test This would mean zero capacitance infinite impedance and infinite bandwidth These are mutually impossible to meet for most situations If you work in a 50 ohm environment then their are methods for working in that environment but since these are boatanchors they have impedances all over the map That means that the probes should be as just described Now in passing no one made better probes than Tek and sus
313. escribed the workings of most tube testers and their limitations The final suggestion was to use substitution Date Tue 26 Oct 2004 10 31 09 0700 From Doug Millar lt dougnhelen moonlink net gt Subject R 390 The Fine Points of Tube Testing found the article on tube testers Very interesting http www 0wned org hstraub testarticle pdf Date Tue 26 Oct 2004 15 25 06 0400 From Drew Papanek lt drewmaster8 13 hotmail com gt Subject R 390 Tube Tester Go to members aol com sbench101 and you will find among other tube projects a design for a homebrew tube tester It is a transconductance tester and incorporates adjustable DC power supplies to operate the tube under test at the same voltages used in an actual application It was primarily intended to characterize tubes to apply them in audio amplifiers but will test our R 390x tubes For the type of test we would like to do some features could be easily added grid emission shorts gas life test An adjustable constant current source in the cathode lead is used to set the tube current that could be removed and the circuit simplified by grounding the cathode and using a bias pot in the grid circuit instead Caveat makes it easier to over dissipate on small tubes The unit could be simplified also by removing the sockets intended for audiophile type tubes removing facility for testing pentodes as triodes removing triode mu testing capability The power transformer rectifie
314. esistance matters at those currents Please excuse this humble opinion if it conflicts with your own faulty reasoning Date Mon 17 Sep 2007 18 18 16 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 OT 30V regulator The 30 volt setup in that meter is a very low current affair Without a schematic I m only guessing but 50 ua is probably the maximum current draw Most of the time the current draw is zero A 9V battery and a capacitor based DC DC converter would do a very nice job Anything beyond that is going to pull way more current for the regulator than your total load If you never want to replace the battery again take a look at a stack of lithium coin cells At 3 volts each a stack of 10 will do the trick Lithiums last pretty much forever on the shelf Date Mon 17 Sep 2007 19 28 29 0500 CDT From Jim Shorney lt jshorney inebraska com gt Subject Re R 390 OT 30V regulator And here s a handy page to calculate the resistor values for the lazy among us http www muzique com schem Im317 htm Date Mon 17 Sep 2007 20 39 51 0400 From Dave Maples lt dsmaples comcast net gt Subject RE R 390 OT 30V regulator All believe an LM723 can be used in a series regulator fashion to regulate well above its ratings Please see the National data sheet for details It may require an external pass transistor Date Mon 17 Sep 2007 19 37 34 0500 CDT From Jim Shorney lt jshorney inebraska com
315. esistor network Obviously with the generator attached to the 125 ohm input there s no way to get the geneerator to see 10 ohms exactly but I m thinking there is a network that might provide a fairly decent match Would a matching transformer be a better choice Can one wind a decent homebrew matching transformer Date Sun 12 Mar 2006 15 15 44 0800 PST From Perry Sandeen lt sandeenpa yahoo com gt Subject R 390 Poor mans R 389 receiver Most of us that don t would like to have a R389 but we aren t allowed to sell the kids or persuade our wives to get 2nd and 3rd jobs Sort of by dumb luck however found a good equivalent on epay that set me back 200 delivered including an operators manual My unit was a little rough so it was a bit cheaper that some of the others they had for sale already had a HP 312B which hadn t got a chance to use play with yet so I ve been lurking around epay looking for another unit Technically it is the HP 3586 Selective Level Meter This description is as underwhelming as calling the Boeing 747 SP400 a people transportation unit This sucker is a real sleeper It has a USB LSB receiver that covers 20Hz to 32Mhz A synthesized VFO output over the same range plus it can be used as a frequency counter As a level meter it goes down around 121dbm That s just for starters It measures all kind of test gear page 131 additional telecom stuff Mine also came with the high stability 10Mhz oven chec
316. esistors or even 100 1 50 and half ohm so you can be sure that the input impedance of the radio is not changing the voltage at it s input terminals Being moderately sure of RF voltage measurements at the microvolt level to 5 or 10 percent is feasible for us At one percent you need all that Agilent or HP can give you Folk who report sensitivity levels to three decimal points are fooling themselves and most folks who read their reports NIST can measure RF levels below one percent but it takes a room full of equipment and half a century of experience Date Wed 23 Sep 2009 09 15 22 0400 From Barry lt n4buq knology net gt Subject R 390 Allen Bradley Potentiometer Numbering Schemes anyone Does anyone know where can find out the value type of an AB pot have It s part of a new to me Krohn Hite function generator and have no schematic for it It s the main frequency control that s getting a bit erratic and would like to look for a possible replacement All it has are some numbers and letters stamped on the back and assume some of those indicate the resistance type taper etc but don t recognized the scheme It doesn t have one of of those long Clarostat style numbers either e g RVXxxxxx JAXXxxxxx etc don t have the numbers with me but thought if someone could point me to a site where these are defined could reference them later today do Know it is a Type J but the other numbers aren t telling me any
317. est gear page 350 possibly a changed RF output stage to avoid the danger of short tube life if you run it at the max output level possibly some solid state parts in the power supply By the way the later versions of the HP 608 also could use the synchronizer With both the 606B and the later 608 s the synchronizer gave you essentially crystal control frequency stability FM capability and other esoteric features gt Of course you can use it without the gt synchronizer and essentially you still have a 606A Exactly gt now use the 8640B which is the cats meow don t have one yet but understand that the prices are coming down steadily on this one The 8640 will do about all you ever need a signal generator for Except be repairable if you blow out the output solid state hybrid module by transmitting into it with a transceiver gt There are a lot of other signal generators that fill the bill as well My very favorite is the General Radio 1001A Standard Signal Generator Old heavy pretty simple has odd output impedances but oh so nice to run Like the door on a Rolls it goes Klunnkkk when you change bands Date Tue 18 Jan 2005 12 35 37 0500 From N4BUQ aol com Subject Re R 390 HP 606 vs URM 25 and it has that high voltage output to drive the frequency counter Date Tue 18 Jan 2005 12 10 03 0600 From Marshall M Dues lt mmdues hal pc org gt Subject Re R 390 HP 606 vs URM 25
318. est jigs from the manual MINIATURE OR NOVAL TUBE SOCKET NO 18 SOLID TINNED WIRES PULL THRU LUGS AND y SOLDER EACH WIRE AT UPPER AND LOWER SOCKET 1 TO3 INCHES CUT OFF FLANGE SO ALTERED TUBE SOCKET WILL FIT INTO TUBE SHIELD BASES ON SUSCHASSIS WIRES PULLED THRU HOLES IN LOWER SOCKET ALL WIRES Takia TRIMMED TO SAME LENGTH Date Sat 11 Aug 2007 19 28 27 0700 PDT From wli lt wli98122 yahoo com gt Subject R 390 re tube extenders test gear page 157 Tube extenders are useful Look in those myriad of unmarked boxes at hamfests found mine there for 2 apiece last year You have to be on the lookout as they do not turn up often One caveat some of them may have a busted wire INSIDE Pays to check continuity between the pin and the test point as well as the socket hole had two such defective extenders easily fixed with a short piece of bare wire and a little surgery on the device understand that many of us never use them they are better at diagnosis than I and need all the help can get Date Sun 12 Aug 2007 07 37 03 0400 From Steve Hobensack lt stevehobensack hotmail com gt Subject R 390 Tube extenders Yes tube extenders are getting rather rare these days made my own It takes a little patience but can be done by most of us Find a miniature tube and socket Break the evacuation tip to destroy the vacuum Use a dremmel tool with a glass cutting wheel or special
319. et computer networks Radio Shack has them believe it or not Date Mon 11 Oct 1999 15 52 17 0500 From A B Bonds lt ab vuse vanderbilt edu gt Subject Re R 390 URM 25 E and URM 25 F I m not so convinced of getting that low a price If one looks at Fair Radio theirs are running around 100 or even slightly more I d rather put 100 into a URM25x than four times 25 into Eico 324s or the like As for what goes wrong the caps in the audio oscillator are often flaky to the point that the oscillator shuts off after warmup It s easy to replace em there are four Date Mon 11 Oct 1999 16 43 12 0500 From Keith Heitzmann lt kk5fe gs verio net gt Subject Re R 390 URM 25 E and URM 25 F agree with this Most of the ones that see are around 75 to 100 bought mine for 75 shipped and thought got a good deal Of course when got it saw why the guy was so generous with the shipping He shipped it without a box Thats right Thank God it had the cover and was intact and in very good shape when it arrived Date Mon 11 Oct 1999 19 00 30 0500 From Phil Mills lt plmills attglobal net gt Subject Re R 390 URM 25 E and URM 25 F bought my last one at a hamfest 2 weeks ago for 50 it was in fairly good shape and had some of the accessories that go in the lid Turns out it works well and is extremely well calibrated with no work on my part Some advice though if you want a working signal generator
320. every bit as good as the D Date Tue 31 Jul 2001 15 34 57 0600 MDT From Richard Loken lt richardlo devax admin athabascau ca gt Subject Re R 390 Unserviceable and Obsolete once bought a Simpson 260 from the Canadian Ministry of Transport who were in charge of air traffic control throughout the country which was tagged as unrepairable It was indeed unrepairable since nothing was wrong with it and used it for ten years before giving it to my nephew Date Tue 31 Jul 2001 20 39 42 0700 From Ed Zeranski lt ezeran concentric net gt Subject Re R 390 Unserviceable and Obsolete test gear page 56 260 just got one on Sunday at a non Ham swapmeet for 5 This one came from a lab in LA and had the batteries remove so no rot They are still out there and they still work Date Wed 1 Aug 2001 09 29 45 0400 From Al2Q Alex lt ai2q adelphia net gt Subject R 390 Obsolete meters Naw In addition to the Simpson 260 that my father bought me in 1952 also use and have just refurbished a 65 year old Weston Industrial Analyzer Model 785 VOM It s about 2 5X the size of a 260 Does anyone else in R 390 land use one This Weston jobbie comes in a polished hardwood case and sports a black bakelite front panel that shine with furniture polish It uses separate terminals for each range of dc and ac current and includes a beautifully machined 100 A shunt the likes of which you just don t see anymore w
321. ew bags of powder and then stuff a URM down the barrel Probably would do more damage to the enemy than the real thing Now that have it working have two sig Gens to cover this range 3 actually if you include a very funky Heathkit The one like is the SS Clemens covers 50kHz to 54MHz and has calibrated slide attenuators etc may eventually end up swapping the URM off it s too early to tell test gear page 333 Date Tue 25 Dec 2001 17 29 03 0500 From Barry Hauser lt barry hausernet com gt Subject Re R 390 A URM 25D Success Story Long Reply sorry T was Christmas morning and all through the house not a creature was stirring not even a mouse except ol Phil was a tinkerin with his URM Twenty Five and lo and behold the modulator s alive Lucky fella What wanna know is where can find a 15 mfd 1600 volt tubular or a reasonable replacement thereof More about that below gt Next pulled the unit out of the case and surveyed the matter 0000 Isn t it amazing how cooperative those lil electrons are They ll just flow throught those lumpy connections like it was nuttin I m sure your soldering job looks spiffy compared to what did around the same time on the opposite coast gt gt Fired her up and voila have modulation and nice clean sounding tones of gt 400 amp 1000Hz or was it CPS in those days You must stick to CPS with boatanchors and their accessories
322. extenders were made commercially Some examples can be seen at http k4che com tube 20extenders TUBE 20EXTENDER 20PAGE 201 ht m For equipment like the 390 390A where the bottoms of many tube sockets are inaccessible without disassembly and even if you disassemble it is often difficult to operate the disassembled radio unless you have extender cables tube extenders can be very useful in troubleshooting faults IME tall ones are often better so that the test point contacts are more likely to clear IF cans and other things mounted near the tube sockets in densely packed chassis Date Tue 22 Feb 2011 20 25 22 0800 PST From wli lt wli98122 yahoo com gt Subject Re R 390 R 390A tube adapter Agree Those tube adapters allow one to check operating voltages very easily and safely in an operating crowded R390A Over the years have stumbled test gear page 245 upon some and found using 3 4 of them in the audio or IF decks invaluble and a real timesaver when trouble shooting Date Wed 23 Feb 2011 19 29 13 0600 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 HP 8640B gears arrived from Italy had heard someone was making brass replacements but have never been able to find the source Date Wed 23 Feb 2011 19 56 14 0500 EST From frankshughes aim com Subject R 390 HP 8640B gears arrived from Italy Here are photos and an action movie movie from Emanuele the gear manufacturer of the
323. f math to work out what the numbers should be The easy way is to plug in a known good tube and fiddle the bias switches until you get a reasonably easy to see reading test gear page 166 Date Sun 28 Oct 2007 06 07 43 0500 From Joel Richey lt richey2 mindspring com gt Subject R 390 Tube testing You cannot test a 6LQ6 in an tube test and get any meaningful results the tube tester cannot simulate the working conditions of that tube and it cannot test an 811 572B 3 500 or any any other transimitting tube Sweep tubes have been aeround for a long time most of the time they loaf but when you shout int the mike the draw a big hung of current do you think your tube tester can simulate that NO Heres my idea take your tube tester out to your trash can and desposit it Just my opinion if you Ike to see the needle move keep using it Date Sun 28 Oct 2007 12 36 05 EDT From Flowertime01 wmconnect com Subject Re R 390 TV 7 U Square peg round hole If you are going to do a lot of these tubes you may want to build an adapter Octal base relays with plastic covers make nice adapters You open the relay top and unsolder the relay wires from the octal socket pins You solder pig tail wires to your new socket and mount it in the top plastic cover of the relay case Feed the pig tail wires into the octal socket base pins Replace the cover screws between the base and cover of the relay Pull the pig tail wires out of the oct
324. f what was available at the time it went through either Depot or the shop that worked on it Modules are VERY well known to have been swapped around to enable the radios to get back into use I ve only seen two radios that had all the modules that were by the manufacturer stated on the dataplate on the front panel Testing by VOM VTVM ESR and or a capacitor tester are all valid methods It becomes a matter of what is available and how one goes about doing what that particular person elects to do actually use a mix My VTVM gets first use IF the radio is up to applying power had an up and functional 67 EAC That made things easier The second one that obtained was one of the original 51 contract Collins Since it was a Blue Striper one of the St Js survivors powering it up was NOT an option Hence you ll get different views as to how you should proceed Miles and Done make very valid points I ll second the touch to feel warmth Either a laser temp device or a thermocouple that comes with a DVM is much preferred than putting one s finger into the midst of circuitry that may well bite one The voltages vary dependent on the particular circuit being examined lt snip gt Date Wed 7 Mar 2012 12 51 40 0600 From Don Cunningham lt donc martineer net gt Subject Re R 390 Capacitor tester THANKS for that information had searched a few years back but didn t find this link Now can have a blue readout one to go
325. ff a half volt it will be off that same half volt at each test point and you re looking for the odd one out most of the time A problem with some particularly auto rangers is that they can change the load to the circuit without you being aware of it and some can inject noise from their converters and other digital circuitry test gear page 31 So it comes down to what you are trying to measure and how much you need to be aware of the peculiarities of the meter you are using These things taken together can help you decide what meter is right for you Date Fri 21 Jan 2000 22 32 12 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 VTVM vs DVM I ve got a couple of modern digital meters a Fluke 77 and a ten or twelve year old RS bench meter mainly use these for messing with solid state stuff like diode voltage drops etc About the thing that use them for in the boatanchor department is measuring resistance values The RS one is handy for testing the gain of transistors I ve never been a big fan of digital meters suspect that it s something about the changing flashing numbers the beeps and the flickering display strikes a raw primal nerve in me Most of them have a sleep mode that causes them to shut down after a while that irks me too Nothing like probing something and looking over and seeing that the display is totally blank because it s sleeping Where s my claw hammer lt grin gt The meter
326. first Just a note for those who like to see some action on the CRT while operating the R390A or nonA or would like to use it in an original test set up Take those scopes out of the storage and get them to work The little devils have a lot of life left in them for years to come and they look quite nice beside our beloved 390s From Scott Barry Clyde B lt cbscott ingr com gt Date Tue 23 Sep 2003 08 11 38 0500 Subject R 390 OT Tubes needed for TEK561A dragged the scope out for something this past weekend and the vertical amp has developed problems checked the tubes and both 6DJ8s EC887 are very weak Just my luck these are apparently popular with the audiophile gang and thus they can be pretty expensive Anyone have any good suggestions on an inexpensive source for these Hopefully the problem is with these tubes have zero experience troubleshooting scopes Fortunately the module is not complex so it might be a simple case of finding a bad component and replacing it of course using the appropriate silver solder which I will also need sigh From Dennis L Wade lt dwade pacbell net gt Date Tue 23 Sep 2003 07 46 03 0700 Subject Re R 390 OT Tubes needed for TEK561A If you haven t found it already you might try the TekScopes list on Yahoogroups There are some true experts hanging out there have a 545A and a 531 but no spare tubes Luckily haven t needed them yet These scopes just keep
327. for transmitter VFOs work on signal generators but getting the RF signal level up to logic levels means shielding of the counter is tougher than shielding the oscillator For sure running most counters to monitor test gear page 319 frequency keeps the oscillator shielding from being of benefit to find the receiver mds So this technique of stabilization is at odds with leakage Generator leakage is found more by poorly shielded receivers Its important to use double shielded or rigid coax connecting cables to cut the stray leakage into the coax Good Belden RG 58 may be only 50 dB down from a wire antenna RS coax that skimps on braid may be a lot worse It takes a lot of attention to details to accomplish MDS measurements that repeat 73 Jerry KOCQ Date Fri 15 Dec 2000 22 17 59 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 URM 25 Stability gt If was going to aim for the least possible RF leakage from a gt 25D G H the first thing I d do is replace the internal coax lead gt from the casting to the attenuator with a the best shielded gt coax could find Maybe even some type of semi rigid copper gt tubing outer covering like is used in microwave applications Good idea gt The next step would be to put a bnc caps on all of the unused bnc jacks on the front panel Should have been done first thing gt gt Next I ve verify that the internal cover on the
328. fun to play with picked up three pieces at the last hamfest bought no radios Oh speaking of which picked up a real dog looking TS 505D VTVM for parts for nine dollars I ve got one packed up around here some where that needs some shunt resistors that haven t found yet At test gear page 33 any rate checked this one out and it pretty much worked After a half a bottle of 409 and a roll of paper towels it looks pretty good spent some time fixing the sticking meter movement and replacing the leads and a few tubes etc I m looking for either a complete manual or at the minimum the calibration instructions if any of you happen to have them Paul there s a mess of good stuff out there but you have to really shop around Some people are still trying to get hundreds of dollars for gear that others want twenty dollars for Date Tue 01 Feb 2000 09 57 50 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Synthetic Oil Tektronix 190B lt snip gt gt Does anybody have opinions on or experience with the Tektronix 190B signal generator fixed a couple of 190 s for friends years ago when NASA Michoud dumped a mess of them as surplus don t think that they were the B model though think that they were A s They were pretty simple to work on The biggest problem was that almost all of the tubes were flat in them Also one of them was missing the output cable and remote attenuator We never could find a replac
329. g with two text files that are additional notes lt http nome comcast net rbethman urm25notes zip gt The zip file contains the noted PDF plus urm 25notes txt urm 25references txt The entire zip size is 287 KB Date Tue 6 Mar 2012 16 05 51 0800 PST From John Saxon lt johnbsaxon yahoo com gt Subject R 390 Capacitor tester recently came into a 390 and 3 390As I must be living right am not an experienced restorer and am looking forward to becoming one Question have been working on equipping my workbench and don t have a capacitor tester Do want one have a multimeter that measures capacitance but don t think it sufficient for testing old caps especially electrolytics am correct Any suggestions Date Tue 06 Mar 2012 19 17 51 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 Capacitor tester You indeed are living right Welcome to the list and welcome to our little part of the world A capacitor testing capability does not hurt You can go for the newer Sprague TO Series testers or you can even go for an older but well functioning Heathkit C 3 or such There is a certain reality to the old gals Look under the modules Should you encounter the old Brown Beauties of Death then don t bother even testing These are an automatic replace item However should you be in possession of something such as a 67 EAC then there will only be a small number to get conce
330. ge at the tube base did notice that when first checked the voltage it was not at 5 0VAC but had drifted downward don t recall the exact value but think it was about 4 6VAC don t have a very convenient way to check the current draw the filament is creating though plan to go through it again checking testpoints tubes and calibration may find other things have gone downhill since worked on it last Date Thu 23 Mar 2006 12 27 18 0800 PST From W Li lt wli98122 yahoo com gt test gear page 133 Subject R 390 re 177 question OT have a nice l 177 tube tester that serves me well recommend Nolan Lee s notes on calibration and maintenance found at http www acadiacom net nlee My question pertains to the Type 83 mercury vapor rectifier Although it was designed to operate upright it is actually mounted on its side in this particular tester Clearly therefore some care is needed in use by letting it warm up for 10 15 minutes to prevent internal flashover My question is about converting this to a solid state device Replacement 83 s are not exactly easy to find Inspecting the schematic the HV takeoff is from the mid point of the 5V filament winding So is there an issue by removing the tube and inserting two silicon 3A silicon rectifiers between this point and the plate pins 2 and 3 would leave pins 1 and 4 unconnected to anything The other question is in regards to the 5Y3GT rectifier W
331. ge at a higher level than what you are pumping down the coax to the antenna connector Leading one to believe you have stumbled on the holy grail of hotness A receiver that is sensitive beyond dis belief Reach up and disconnect the coax from the signal generator are you still receiving the signal It s leakage Date Fri 02 Mar 2012 12 26 07 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 AN URM 25s test gear page 385 accept the description However Roger R and his equals that worked on this specific combination of AN URM 25s and R 390s R 390As achieved some very impressive results The got very good S N ratios and high sensitivity lt snip gt Date Fri 2 Mar 2012 19 16 39 0500 EST From Roger Ruszkowski lt flowertime01 wmconnect com gt Subject Re R 390 AN URM 25s Its not so much that we worry about leaking on the bench It s when you go back to trying to receive with that radio At Ft Devens Mass about 50 miles from WBZ Boston WBZ was every where on the dial To get WBZ every where it had to mix with some thing else in some kind of mixer We found all kinds of things that would mix two RF signals OK WBZ and some other signal pick on WBZ but almost every other AM station had a signal at more than on spot on the R390 A s with just a 3 foot test lead for an antenna in the class room Radios all over that base were radiating non stop as were generators and transmitters wish had a ra
332. generator to get everything to pass Date Mon 28 Feb 2005 17 50 04 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 URM 25 replacement URM 25 folks got both a URM 25 and a URM 26 this weeekend The URM 26 20 to 440 mc or so uses a waveguide beyond cutoff attenuator so there is only one single resisor in the attenuator The URM 25 is a switched ladder attenuator checked mine by measuring the dc resistance at the output jack One setting 1 uV was way above 50 ohms something like 700 Crispy critter resistor at that spot Another was modestly off and all the rest were close to 50 ohms Gotta find some proper resistors to repair that attenuator gt They switch in a variety of fixed attenuators to make up your final gt attenuation value At any given setting you may have a fairly small gt number of pads in the circuit With an external attenuator and a receiver gt R390 recommended you can step through the entire range of the gt generator Since the attenuator is the part most likely to fail in a gt non obvious way it s worth doing on a new to you generator gt gt Checking the pads you use is probably a good idea It turns out you can do gt a quick and dirty check on any pad with the same technique Terminate gt one end of the pad with 50 ohms Use your DVM to measure the resistance on gt the other end It should be 50 ohms Reverse the pad and repeat the gt procedure Pads tend to die
333. ghest there was a gradual increase in the output frequency peaking at a little over 4 at about 3 4 of the way up the dial and then dropping off rather sharply as it approached the upper endpoiint Someone bent the fins outward on the tuning capaitor in an apparent attempt to correct the linearity or perhaps more accurately alignment with the dial markings however from what could tell this was the wrong thing to do Since the frequency was too high at the bad points then according to the LC formula there isn t enough C or perhaps not enough L at that position At any rate decreasing C didn t seem right and straightened the fins The linearity is better now about 3 max but it s still on the high side Again assume this indicates eiher not enough C or not enough L at these positions Looking at the capacitor it appears it is a custom made job that was designed for a particular capacitance curve The edges of the rotors are not round but have flats along the way presume this is to shape the capacitor to agree with curve so as to align with the dial markings hope that made sense At any rate it appears there isn t enough C at or near the midpoint of the rotation so the output frequency doesn t match the dial all along its travel Is there a common knowledge way to get around this While can always ignore the dial markings and use the frequency counter I d like it to be within spec if possible The trimmer c
334. going and going and going From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 OT Tubes needed for TEK561A Date Tue 23 Sep 2003 09 51 52 0500 I ll probably have to join that group if they ll have me This group though is pretty amazing Within 45 minutes of posting have two businesses with the tubes for 8 each as well as some I have some tubes I d be glad to send you My initial search turned up some of the more expensive European brands at 20 each and that s what was trying to avoid test gear page 29 From B Riches lt bill riches verizon net gt Date Tue 23 Mar 2004 08 30 33 0500 Subject R 390 Test equipment repair Any idea of a person that repairs Tek scopes remember seeing a name of someone in the Midwest Date Tue 23 Mar 2004 16 27 45 0200 From Bryce Ringwood lt BRingwoo csir co za gt Subject Re R 390 Test equipment repair If you fancy doing it yourself see TekScopes YahooGroups com Look for Stan Griffiths on Google The older Tek scopes are nice to work on and have really good manuals don t know if yours is old or new Hope this helps Bryce Date Tue 19 Oct 1999 13 45 0700 PDT From rlruszkowski west raytheon com Subject Re R 390 AN TRM 1 gt AN TRM 1 Has anyone used one of these acquired one a while back and intended to use it to help align my R390A Although it isn t the URM25x does anyone know if it is a good enough unit have c
335. got the single most comprehensive list of tube types that it can test of any of the military testers The Govt supported them as far as settings data well up into the 1980 s In addition there are compactron adapters nuvistor adapters etc for them They re pretty versatile If could have a second it d be the TV 2 series Rather large and heavy they re fairly easy to find parts for and are very easy to work on There s so much room in them that they came with spare tubes fuses etc all integral with the tester There are no previsions for calibration If the five meters are right and none of the resistors have drifted out of spec it s on the money period There s a pretty decent number of tubes that it can test but there isn t as much published data for them as the TV 7 series Due to the large number of controls they re not nearly as fast to set up as the TV 7D If you re clever and have access to the published tube specs on a particular tube that s not listed on the roll chart or in the supplement book you can easily determine the setting and test it The plate screen bias filament etc voltages can each be manually set using the separate meters and controls for each of these functions Then you convert the reading into micromhos and compare it with the published tube data If you want to monitor the current of any of the specific voltages it s a simple matter to build a simple adapter with an old tube base or plug and an extra tube so
336. grid voltage to determine whether an oscillator is running The only other service tool that have found really useful is an EICO Model 950 R C bridge to measure capacitor values amp leakage but you can live without it especially if you intend to re cap the R 390A Date Fri 13 Feb 2009 08 06 51 0600 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 test equipment question If it s just a matter of cleaning them up checking and replacing tubes and then alignment you have it covered If you have to do any troubleshooting find myself lost without an O scope frequency counter and my trusty cap analyzer That s not to say it can t be done without those items because guys do it every day Just like any job the tools make the job a bit easier and certainly more pleasurable If had to leave any of the above on the table would keep the O scope One can be bought cheap usually ebay is a good source for test gear cheap Most all use came from there and it s all HP and Tektronics Date Fri 13 Feb 2009 14 32 17 0000 From Bill Kirkland lt kirklandb sympatico ca gt Subject Re R 390 test equipment question haven t done my R390 a s yet but have done several sp 600 s ooops wrong group Once you have done the resistance checks and voltage checks think you are half way there If you have to dig into a module gather extension cables would be handy These are cables which allow you to remove the
337. gt Subject Collins Interpretation of 30L 1 manual sec 4 7 This afternoon was reading 30L 1 manuals to clear memory cobwebs before adjusting a unit happen to have the 5th and 8th editions on hand When got to the TUNE METER ADJUSTMENT section 4 7 g noted what feel is a confusion factor Once you have increased exciter drive to the point of distortion onset you should see a minimum of 450 V p p on the scope if you use this method The 450 V p p minimum output voltage requirement is clearly associated with the peaks of the 2 tone RF waveform envelope This would correspond to a minimum output requirement of 506 Watts into 50 Ohms Since this check is done with 2 tone excitation why would the RMS voltage 160 VRMS actually 159 if you run the numbers corresponding to 450 V p p be stated in the manual Since my scope can only handle 400 V p p without an external calibrated attenuator don t use the measurement method called for Instead place directional couplers in the input and output lines of the amplifier to create an X Y display on the scope can get much more reliable detection of distortion onset also place a wattmeter in the amp output line My interpretation of all this is that the minimum power output with 2 tone excitation at distortion onset as indicated by a wattmeter should be 506 2 206 Watts test gear page 221 Have missed something Yes know that the Tuning Indicator can be problematic but I
338. gt Subject Re R 390 OT 30V regulator Again the LM317 The 40 volt rating is for input output differential You can regulate voltages higher than 40 volts as long as the difference between input test gear page 162 and output voltages does not exceed 40 volts You can configure them with a pass transistor for higher currents check the app notes in the PDF datasheet http www national com mpf LM LM317 html And do include the recommended protection diodes and bypass capacitors you won t regret it Date Mon 17 Sep 2007 17 55 22 0700 PDT From Masters Andy lt nu50o yahoo com gt Subject R 390 150 V regulator Based on National Semiconductors website and their statement that the LM317HV operates isolated and can handle several hundred volts as long as the input output difference is not more than 40v could this device not be used as a very nice 150v regulator replacing the OA2 Date Mon 17 Sep 2007 21 01 34 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 150 V regulator The OA2 is basically a shunt regulator The easy way to solid state it is with a couple of zeners If you want something more fancy a combo of a zener a resistor and an MJE 340 will do quite well Date Tue 18 Sep 2007 00 04 24 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 OT 30V regulator If you want to build your own there is no need to go fully discrete use an op amp driving a level transl
339. gt Don t forget to mention the British AVO MkIII tester think it s one of gt the best tube testers in existence Probably THE BEST Date Sun 25 Feb 2001 14 22 17 0800 From khgrant ix netcom com lt khgrant ix netcom com gt Subject R 390 Tube Testing Question picked up a cheap tube tester a Sencor T136 and started testing tubes in my R390A All of the ones I ve tested so far read questionable or slightly low on the emissions scale I m trying to figure out whether this is due to the tester or the tubes can adjust the cal level on the tester to full scale so at least the tester seems to work Just what does the transconductance measurement test How does it bias the tube Might have tubes that need to be replaced or is my tester not very accurate Date Sat 7 Apr 2001 10 17 15 0700 From Robert Dunn lt robdunn1 earthlink net gt Subject R 390 RE ForSale Swap FS Replacement RF Probes for VTVMs USM 116 is the military equivalent but not clone of the HP 410B electronic voltmeter This probe uses the same vacuum tube UHF diode in the probe as the HP s so for anyone needing this diode it is a good deal The probes are good to about 700 MHz but of course the need the 5v or 6v filament supply The probe is not exactly the same but at least it can be carefully very carefully disassembled for cable replacement and the differences between it and the HP probe are small enought that adapted mine for use with a
340. h a couple test gear page 386 of microvolts of RF being generated it is heard in several receivers nearby but when below 0 35Uv or so it does not happen At least have not seen it Date Sat 03 Mar 2012 12 08 47 0500 From rbethman lt rbethman comcast net gt Subject R 390 HP 410B Pics The pics of the HP 410B chin connection jacks are now up on Mike s site lt http namstuff ath cx gt Date Sat 3 Mar 2012 12 23 34 0500 From Thomas Chirhart lt k4ncgva gmail com gt Subject R 390 AN URM 25 rebuild Was it the R 390 list or another subscribe to that identified a YL that specialized in reworking URM 25 s Can anyone ID her and contact info just picked up a decent 25 D and would like it checked put Reply direct if you prefer Date Sat 03 Mar 2012 12 32 32 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 AN URM 25 rebuild That WAS Ashley Hall Kiss Electronics com However she and her crew no longer do this do have their parts list and procedure for the rework It is on line at lt http nome comcast net rbethman Parts Proc txt gt Date Mon 05 Mar 2012 23 04 07 0800 From Jim Hill lt JJan 3 cox net gt Subject R 390 AN URM 25D Repair Info More lt snip gt If you decide to refurbish your AN URM 25D there s an excellent article in the Hollow State Newsletter written by Dallas Lankford The generator is inconveniently small for easy repairs and the article gui
341. ha pdq com gt Subject Re R 390 R 390A Manuals and O Scope watched 465 scope prices for awhile on eBay and bought several there Roughly speaking working 465 scopes seem to be 125 working 465M military 465 with dual timebase for maybe 150 and 465B dual timebase also has auto 10X probe light for maybe 200 picked up a working 465M for 117 a broken 465B for 160 or so a working 475M for 210 and a working with numerous good 10X probes for 180 I m sure you can do better but you can do a lot worse too Be careful to watch the descriptions if they don t show two traces with signals assume the scope is DOA and move on to the next scope unless you are looking for parts and the price is low also think you should ignore claims about being in current calibration unless they are a reputable shop with a guarantee know they also have DM44 add ons voltage measurement period measurement of some sort and other models of scopes 475 475M 466 and so on not to mention all the 7xxx series scopes which have to say are rather large In retrospect I d only get one of those if knew wanted to get a 7L5 frequency analyzer which do want Date Wed 03 Jan 2001 16 10 20 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 Tek Scopes All 465 were dual trace 10X light and delayed sweep The M is a sturdier and better shielded package don t recall the A the B
342. hat decided to standardize on the 7704A other than the fact that a mess of them were cut loose surplus locally for next to nothing over at Keesler AFB was the fact that they re a fraction of the cost of the hot 79xx scopes 3 and 400 MHz scopes All mess with is HF My old 50 MHz Tek 547 has never not been enough scope for anything I ve ever needed to do can t see paying a serious premium for a 7904 or faster mainframe Date Fri 2 Jun 2000 13 40 38 0500 From Scott Barry Clyde B lt cbscott ingr com gt Subject R 390 DQT Was Need Advice on O Scope DQT Dumb Question Time How do determine the bandwidth and or frequency response of my scope have a TEK 561A with no paperwork It goes down to 1us div for the sweep speed but don t think that is the determining factor Does frequency response have to do with its ability to lock onto a signal of a given frequency How does bandwidth figure into this First scope and it shows test gear page 16 Date Fri 02 Jun 2000 13 15 36 0500 From Dr Gerald N Johnson lt geraldj ames net gt Subject Re R 390 DQT Was Need Advice on O Scope There are two determining factors in a scope s bandwidth the main frame including the CRT and the plug in Some of the vertical plug ins for the 561 are under 1 MHz bandwidth That means about 1 microsecond rise time Some are 10 MHz bandwidth don t think it gets out to 30 MHz with any plug in but I m not sure about th
343. hat last one is very clearly marked as a may not exceed in the service manual Also its Zin is 50 ohms another way to get things messed up It leaves the cap on or it gets hosed test gear page 220 Date Sun 21 Feb 2010 02 55 05 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP 8640B Question Re RF leakage from 8640Bs I ve lost track of who brought up leakage but the 8640B specs say Leakage With all unused outputs terminated properly Leakage limits are below those specified in MIL l 6181D Furthermore less than 3 uV is induced in a 2 turn 1 inch diameter loop 1 inch away from any surface and measured into a 50 ohm receiver This permits sensitivity measurements to at least lt 0 03 uV in a shielded system For reference 3 uV is about S5 on a receiver with a 50 ohm input and a calibrated S meter which most aren t That MIL spec has been superseded by MIL STD 461 http Awww everyspec com MIL STD MIL STD 0300 0499 MIL STD 461F_19035 The testing methods for MIL STD 461 are detailed in MIL STD 462 http Awww everyspec com MIL STD MIL STD 0300 0499 MIL_STD_462d_1322 The 8640B is not exactly Tempest certifiable but very respectable If all outputs are properly terminated and you can hear it on a radio the antenna of which doesn t come any closer than 6 to the 8640B it s not working to spec Date Sun 21 Feb 2010 16 21 53 0800 From Robert Jefferis lt jefferis antelecom net
344. hat the larger caps had been left out of later production units Date Sat 19 Feb 2011 23 40 38 0500 From Barry lt n4buq knology net gt Subject Re R 390 HP 410B Question That s what figured While the meter will function without that 50uF think will replace it really like the damped meter movement on these VTVMs Date Tue 22 Feb 2011 12 14 45 0600 From Tisha Hayes lt tisha hayes gmail com gt test gear page 244 Subject Re R 390 R 390A tube adapter The tube adapter is really an extender so you can access the pin connections on a tube base to measure voltages or resistances Many folks who have serviced these radios professionally military have indicated that they never used them They are homebrew devices with a pin base and a socket attached with fairly inflexible wire so you can raise the height of the tube up to a point where you can get to the individual pins little loops or taps to connect at the top tube socket There are a few drawings that give examples of what these look like Date Tue 22 Feb 2011 10 32 32 0800 From Dennis Wade lt sacramento cyclist gmail com gt Subject Re R 390 R 390A tube adapter have found commercial versions of these devices i e 7 and 9 pin test sockets useful when looking at tube pin voltages and signals Date Tue 22 Feb 2011 13 54 12 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 R 390A tube adapter Back in the day tube
345. hat we might as well just check them with a signal generator in the radio Noise figure would be a very interesting thing to measure on a tube by tube basis The same issues about tuning the input and output circuits would apply but we might get some useful data That project is a bit more involved than what had in mind So guess there s been enough interest I ll go off and see what can figure out for a circuit When do I ll let the group know Date Thu 28 Oct 2004 11 18 25 0400 From Scott Bauer lt odyslim comcast net gt Subject R 390 Noise test Well since we are testing tubes this week can somebody explain noise tests have the correct headphones which plug right into my TV 7 Now the question test gear page 114 Is there a specific test or does one just plug the phones in and tap on the tube and listen for microphonics Date Thu 28 Oct 2004 21 22 41 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 Noise test You got the right idea You can also catch odd clicks and pops this way Date Tue 28 Dec 2004 13 18 10 0800 From Kenneth G Gordon lt kgordon moscow com gt Subject Re R 390 me radio ist bloken gt hate to ask this but what does a milspec tube tester go for in this lifetime Depends on the tester looked some up on that auction place a couple of days ago A TV 2B U was going for over 300 A TV 7 was about 150 less A Hickock 539 was going for over 600 Ya pays yer mo
346. hat you gents use to check caps Would a Heath IT 11 work well for vintage BA think have a C551 problem Date Fri 20 Apr 2007 12 52 42 0700 From Kenneth G Gordon lt kgordon2006 verizon net gt Subject Re R 390 Capacitor checkers Yes Heath IT 11 use a restored rebuilt Heathkit C 3 which is quite ancient but does the job However there are better in the sense of more capable instruments available The Sprague TelOhmMike TO 4 5 and 6 s are excellent and there are others like them think the TO 5 will also check transformers but the TO 6 doesn t AFAIK the all the TO instruments will reform electrolytics Date Fri 20 Apr 2007 16 11 58 0500 From Patrick lt brookbank triad rr com gt Subject Re R 390 Capacitor checkers In regards to the Sprague TelOhmMike TO 4 does anyone have a operational manual for it would like to aquire one original copy hard copy or softcopy does no matter Any help would be appreciated Pat test gear page 145 Date 20 Apr 2007 20 20 27 0000 From n4bug knology net lt n4buq knology net gt Subject Re R 390 Capacitor checkers If it turns out you do have problems with C551 you might want to look at some pictures of one way solved the problem http www knology net thelanding R390A AGC It looks kind of funny but if you don t like cutting into oil filled caps etc this works and doesn t require any hacking to the IF deck Also you allows you to experi
347. hat you think PS A G Tannenbaum seems to have the best deals on the manuals have to pick up If there s any better deals to be found I d like to hear about them Thanks for any input Daren Date Mon 03 Sep 2001 15 39 05 0500 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Opinion on HP 606b sig gen gt and found a drop dead beautiful HP 606b signal generator The manuals for the 606A will hold you until you can track down a schematic for the 606B They are basically the same except that the B has a SS PS anda separate tap for a frequency counter At any rate the manuals are a bit too large to attach Somewhere around 8 megs encoded as an email attachment Give me FTP access somewhere other than one of the free storage places that harvest user information and I ll upload it for you test gear page 58 gt HP 400d and 2 more HP 400h s Check your attachments directory and you ll find scans of three manuals for the HP 400 series Date Mon 3 Sep 2001 16 08 08 0700 From Bob Tetrault lt rstetrault home com gt Subject RE R 390 Opinion on HP 606b sig gen Buy that sucker Deal down if you can but barring a few rare GenRads it s the best of the tube styles Stable phase lockable with the HP 8708 Synchronizer and with the best attenuator IMHO which also reads out n dBm as well as microVolts Got one and a URM 25H or J and preferentially use the HP I ve seen them for 325 from
348. he Test Equipment qth list Apparently someone is trying to get a good one so that BETTER ones can be made You may want to join and search the archives or just search that lists archives One site lt http jvgavila com hp8640b htm gt shows the split gear clearly This causes the gear assembly to jump a tooth or two no doubt causing it to NOT be where it is supposed to be Apparently this is true of similar numbered instruments Date Thu 18 Feb 2010 21 48 44 0600 From Barry lt n4buq knology net gt Subject Re R 390 HP 8640B Question It may very well have been on the Test Equipment list that saw something about the replacement gears Yes did see the pics on Jose s site There s one up for bid on eBay and think it s just in need of gear work Date Fri 19 Feb 2010 02 26 21 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP 8640B Question There are quite a number of Nylon gears all readily apparent when you take one apart and at least two basic failure modes The collars split which means you can t tighten the gear on the shaft and the large gears shrink and some warp over time so they skip teeth Once the teeth skip you either park it and look for a new gear or ruin the gears by trying to use it and ruining the teeth Any 8640B on eBay that is not guaranteed by an upstanding seller to be working properly will invariably have ruined teeth on several gears and usually broken and s
349. he meter is an ordinary run of the mill 50UA movement Simpson think easily found a replacement and simply swapped dials didn t even have to drill new holes in the dial for the mounting screws Date Thu 01 Mar 2012 13 35 48 0500 From rbethman lt rbethman comcast net gt Subject R 390 HP 410Bs and AN URM 25s Ashley Hall HMIC Head Mother In Charge lt Kiss Electronics com gt no longer refurbs or supports the AN URM 25s However She provided me with a parts list for what the used to do She also provided me Their procedure for refurbishing can provide this to any and all that desire this If enough want this info I ll put it on my site for download She and her crew are providing the equivalent services for HP 410s recently procured a DC probe for mine My HP 410B is a peculiar one My probes are NOT soldered in under the chin Either a previous owner built a beautiful aluminum piece with banana jacks for ohms and common and 1 4 Phone jacks for the DC and AC probes OR it is a prototype don t know which but it was done in a very professional manner It makes thing a lot neater on the bench as when not in use the meter can sit on a shelf and all the probes can be hung up out of the way I ve checked the HP 410B against known 1 resistors known DC source of 3 7VDC and checked the AC by a known fixed voltage The old gal is right up to snuff test gear page 378 Date Thu 1 Mar 2012 13 51 42 0500
350. he 70 s and 80s A common fault found with the 547 s is the filament winding for the CRT going down to earth Rather than replacing the whole transformer used to connect up aseparate well insulated filament transformer the cathode is about 1500V above earth This fixed the problem The commonest fault used to find in all the 500 series Cros was Failed open circuit dried out Electrolytic Bypass cap for the 50Khz osc in the Eht supply the Oscillator tube has grid leak bias and as the 50Khz wanders around the chassis the output drops off and the Bias gets less dissipation goes up and eventually the tube plate glows red symptoms the Trace is bright when first turned on then gets dimmer after about 5 minutes goes out altogether Got to know these units pretty well Overall they were pretty good the 547 s had a Tunnel diode trigger circuit The tunnel diodes used to fail there is one in each timebase so the other could be changed around to check the fault and the Miller time base could be tricky remember one very difficult to find Fault ended up Meggar testing Every cap in the A timebase One 500Pf cap measured 300Megohms when replaced that it worked perfectly the miller timebases rely on the tubes internal capacity to oscillate and it doesn t take much to stop Date Sun 1 Apr 2012 09 07 07 0700 From Pete Lancashire lt pete petelancashire com gt test gear page 401 Subject Re R 390 Tek 500 series CRO s
351. he correct number is 323 and here is one source http www bulbman com index php main_page product_bulb_info amp products_id 15763 About 4 ea plus shipping Date Sat 18 Jul 2009 22 56 46 0400 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 URM 25D dial lamps These lamps have long been either hard to find or pricey remember prices in the past being much higher than the 4 from the above source The URM 25 D uses four of them The F model used different lamps altogether If you relamp your D suggest you masure the actual lamp voltage and consider increasing the dropping resistor value to extend the life Some fellows in the past have changed the lamp type altogether to use a lamp more affordable and findable and incidentally increase the amount of light that gets to the dial Date Sat 18 Jul 2009 20 29 23 0700 From Craig C Heaton lt wd8kdg worldnet att net gt Subject Re R 390 URM 25D dial lamps I ve already sent this information to Steve about the CM323 bulbs for the URM 25D The best price in town so far is jkllamps com minimum order of 10 1 50 ea plus shipping My 25D takes 2 of these 323 s for the dial and one NE 51 for the ON indicator The 323 number believe is a Chicago Miniature Date Sun 19 Jul 2009 07 34 25 0700 PDT From stoth47 yahoo com Subject Re R 390 URM 25D dial lamps test gear page 373 Thanks Craig for the URL on getting the lamps Also thanks Dave for con
352. he last filter cap where use a cheap RS DVM to do the job Someone else complained about having lots of hum on the XTAL CAL OUT audio I do also but not objectionably and finding that removing C204 helped that hum That s a strange one that don t understand analytically but respect the report was given Caveat You might consider replacing ALL the caps on the audio board After all it s a pain to take that module apart and caps aren t that expensive Bit messy undoing all those solder connections but what the hey You also might consider checking out R130 and ALL the resistors in the attenuator With the attenuator electrically DISCONNECTED from the unit you should measure the following resistances between the identified nodes Between X10K and ground 55 56 ohms X1K to ground 50 05 X100 to ground 49 99 X10 to ground 49 99 X1 to ground 49 99 X 1 to ground 50 00 between X10K and X1K 94 50 X1K to X100 90 03 X100 to X10 89 99 X10 to X1 89 99 X1 to X 1 89 99 Someone else suggested replacing all coax s with new including the internal one from the attenuator I m using a moderately flexible Times RG58 more or less equivalent since the diameters are somewhat different equivalent with double shielding available from The RF Connection near Gaithersburg look for Roy Morgan s e mails and you ll see the reference test gear page 298 Take R119 R127 R173 apart and clean with DeOxit My R119 was pretty scratchy and hope to s
353. hemist thus electrically conductive through a thin boundary layer and independently a low vapor pressure implying that it won t disappear over time lubricant Stabilant isn t cheap but it s made by a low volume boutique operation in Canada thus doesn t catch the economics of large scale production On the other hand maybe about the time head for the barn 30 or so years hence I ll know the long term lubrication and conduction capabilities of Stabilant THUS IN THE LONG RUN THE PRODUCT MAY BE VERY CHEAP Date Fri 04 Feb 2000 08 37 08 0600 From Nolan Lee lt nlee gs verio net gt Subject R 390 URM 25D pots test gear page 303 gt Reference your lubricating potentiometers Glad you got it finished know that changing those capacitors is a royal pain but over the long haul it ll be well worth it I m guessing that you didn t have any problems with the alignment then that s good gt The microvolts pot was very nonlinear up near the top end Bad pots are a pretty common problem in the URM 25x s had an interesting problem calibrating one caused by the adjustment pot for that circuit having increased in overall value from 2 5K to about 5 5K The only decent quality spare 2 5K pot that had was and A B type J The killer was that it had a conventional shaft without the locking provisions ended up cutting up another type J that had what needed and assembled one pot from tw
354. her NASA Michoud and Stennis Space Center had pallet loads of these things selling for dirt 15 years ago was told test gear page 32 that they were used for measuring the resistance values of harness connectors and harness wiring in the Saturn V sections that were build here For really accurate measurements of relatively constant DC and AC voltages use a Fluke 893A differential voltmeter A thousandth of a volt is not a problem on the low end This meter is very handy for checking and calibrating panel meter and test equipment meter movements etc with nothing more than a battery and some resistors and pots It s good for about 1100 volts AC DC don t have the manual handy but I think that the accuracy is along the lines of a hundredth of a percent Pretty slick piece of gear for 25 00 or so This one is pretty and a recent addition and makes the fourth one I ve owned picked up three of them ten years ago for next to nothing This type of lab instrument is rapidly being surplused out of the military and industry due to the fact that it takes time to use it and you have to pay attention to decimal places the null meter etc For AC voltage and AC and DC current measurements especially varying ones I ve got about a dozen or so different Weston portable lab meters I ve got them from 10 ma FS to 50 amps FS for current an up to 750 volts FS as far as AC voltage is concerned The average accuracy of these is about a half of a percent
355. her than the D and the F Speaking of which could really use a copy of the manual for the Conar 280 signal generator If I m going to spend any time fixing up a piece of test gear or a receiver for that matter I d like it either work as well as it did when it left the factory or better Hopefully better gt Confused as usual Not at all guess that I m just a little bit fanatical about some aspects of electronic gear doubt that anyone else on the entire planet spent several evenings measuring the resistance values of each of the wires in the main chassis harness of their R390A down to the thousandth of an ohm or checked the repeatability of the slug racks in the R390A with a dial indicator I ve spend untold hours dissembling and calibrating the meter movements in a lot of my stuff because they weren t as accurate as they could be The fact that the paint is starting to wear off of the tuning knobs doesn t bother me at all don t have a real big electronics hobby budget and a lot of the more modern an accurate test equipment that I d love to have is way beyond my reach guess that tend to overcompensate and try to turn some aspects of what do have into the best that can I ll be honest with you though Just knowing that had replaced one of the resistors in the attenuator with an out of spec value would bother the hell out of me every time looked at it Date Mon 10 Jan 2000 04 05 42 EST From Wn4i aol com Subj
356. here have all the skilled machinists gone Like my R 390 the inside of this VOM smells just great when you open the metal sub enclosure The smell is a mix of varnish and wax and phenolic Very nostalgic Reminds me of my early ham radio days in the late 1950s BTW the Weston 785 is my standard against which judge all my DMMs and against which calibrate my homebrew metering circuits Unlike the DMMs that sometimes go bonkers it shrugs off RF from transmitters under test Date Fri 31 Aug 2001 12 43 18 0400 From Roy Morgan lt roy morgan nist gov gt Subject R 390 DMM probes load the test points had suggested to Peter that he put a one megohm resistor at the end of his DMM voltage probe to isolate the meter from the circuits he was measuring He had gotten low readings at most of the test points during alignment attempts The un isolated DMM voltage probe loads the circuits at the test points and you cannot get proper readings Most VTVM s contemporary with the R 390 radios had a one meg resistor in the DC probe I assume that the TS 505 has this The Heath V 7A and RCA Volt Ohmists do suggest that all owners of R 390 radios equip themselves with a nice VTVM of proper age and having an easy to read moving needle meter on the front No one needs to measure the test point or diode load voltages to three decimal places You do need to watch the nice moving needle as you make adjustments test gear page 57 Date F
357. here is something very wrong with your URM 25 Push and pull on the frequency set knob if the frequency changes much the shaft end play mechanism is loose Gotta fix that Other wise something else is out of whack From Jim Temple lt jetemp insightbb com gt Date Sat 18 May 2002 12 20 51 0400 Subject R 390 URM 25D manual have picked up one of these signal generators The modulation does not work as is the case with many of these models The archives is a great source of information and tips for maintaining one of these Does anyone know of a manual for the D model that is available on the web or in pdf format Thanks for your past support test gear page 336 From Alan Johnson lt alanjohnson gbis com gt Date Sat 18 May 2002 10 03 31 0700 Subject R 390 OT URM 25F This is off topic but picked up a 25F at a hamfest last week and would like to know if there are any must check fix items that must be attended to prior to firing up the unit Also does anyone know of a reasonably priced source for Collins FA series filters for the 75S 3B C receivers need an AM filter From Jim Temple lt jetemp insightbb com gt Subject Fw R 390 URM 25D manual Date Sat 18 May 2002 13 04 04 0400 WOW that was fast The D model Navy manual is available in pdf format at http Awww kg7bz com Manuals html Thanks for the quick responses From Jim Temple lt jetemp insightbb com gt Date Mon 24 Jun 2002 12
358. hesized sweeper to get the IFs to where they can be and noise source to properly characterize sensitivity rather than the bogus numbers you can get by tuning the SigGen to a hot spot peak in the IF response New rant So yes you can do good things to an R 390 with a URM 25 and a PSM 4 On the other hand you can do bad things with a tv xx The only useful tube tester you should use and will ever need is the R 390 What you get from a tube tester is meaningless where it is critical and frequently condemns perfectly usable tubes Instead of spending money on tube testers you should spend it on a collection of spare tubes Date Sun 15 Feb 2009 14 12 26 0600 From Tom Frobase lt tfrobase gmail com gt Subject Re R 390 test equipment question have been watching this thread for a while and thought would weigh in am fortunate to have invested in a fair amount of test equipment over the years Most by buying it broken and repairing it My love of test equipment is just as avid as for old radio s use an IFR 1200 service monitor for a signal generator Both frequency and gain are calibrated saving time each time move the dial use an HP 3577 to adjust the IF chain can truthfully say have tried doing IF alignment the old way and have always improved my work with the analyzer Of the many R 390 s and A s have repaired it is always a thrill after all of the RF coils and mechanical assembly has been removed clean
359. hile the ZM 11 uses AC for all measurements From Bill Smith lt billsmith ispwest com gt Subject Re R 390 URM 90 LCR bridge question OT Date Tue 24 Jun 2003 09 04 59 0700 Does anyone have a spare manual for the ZM 11 U test gear page 92 Date Tue 24 Jun 2003 11 29 45 0500 From Dave Merrill lt r390a rcn com gt Subject Re R 390 URM 90 LCR bridge question OT There is one on BAMA ftp oama sbc edu downloads miltest zm1 1u Date Wed 25 Jun 2003 08 52 11 0400 From K2CBY aol com Subject R 390 URM 90 LCR bridge Bill Smith ZM 11 Manual OT The ZM 11 U manual posted on BAMA leaves a lot to be desired Apparently it is a preliminary draft based on the prototype rather than the production unit A lot of the component values shown on the BAMA parts list and schematic are high precision specialty parts while the box itself uses garden variety 5 and 10 parts for most everything except the bridge standards and the meter multipliers amp shunts The biggest problem is that the BAMA voltage resistance diagram and chart are incomplete A lot of the values are shown just as lettered footnotes but the footnotes table is not present To further complicate matters there is also a ZM 11B U model which am told uses a slightly different tube lineup posted a query similar to yours to the Milsurplus digest page a week or two ago and was referred to http www pacificsites com brooke CDW shtml Fair Radio a
360. hms impedence instead of the usual 50 ohms A 10 db 50 ohm pi filter would have 96 25 ohm shunt resistors and a 71 15 ohm series resistor values from the 10 db step of the HP606 output attenuator Hard to buy those 1 2 precision resistors also Date Fri 7 Sep 2001 07 27 53 0400 From Tom Leiper lt twleiper juno com gt Subject Re R 390 recommendation for rf signal generater gt But did you mean the attenuator started life with a 50K series resistor No It was just an L pad and ripped everything out to use the nice little tubular case Date Thu 11 Oct 2001 13 45 59 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject RE R 390 Sensitivity Measurement If you take the URM 25 attenuator apart be aware of the ball bearing spring phenolic post in the center of the housing Date Fri 12 Oct 2001 21 37 57 EDT From DJED1 aol com Subject Re R 390 Sensitivity Measurement test gear page 326 The URM 25 attenuator is not a wavegide below cutoff it s a resistive power divider know that the signal is not detectible on my R 390A when crank the attenuator all the way down An alternative is to shift the signal generator off frequency Date Wed 7 Nov 2001 01 52 57 0800 PST From MICHAEL OBRIEN lt mikobrien excite com gt Subject R 390 Tags on urm 25d just bought a urm 25 generator from fair radio checked unit It looks complete with all the adapters manual etc When was looking for one
361. hours of heater alone to improve the gas situation especially those stored more than a few years Date Thu 14 Dec 2000 11 27 35 0600 From Scott Barry Clyde B lt cbscott ingr com gt test gear page 313 Subject RE R 390 URM 25 Stability Yes it s an air variable hadn t thought about humidity It is certainly a fast acting phenomenon perhaps too fast to be temperature Humidity is a good thought Perhaps should get out the hair dryer instead If it s more just humidity than temperature then closing it back up will be a 98 fix It s not hermetically sealed but it s not directly in any airflow either Date Thu 14 Dec 2000 17 11 39 0800 PST From Joe Foley lt redmenaced yahoo com gt Subject RE R 390 URM 25 Stability Well don t know what yours is built like but think that is a big concern because the URM 25 variable cap is inside the big cast aluminum chamber inside the generator s case That inside chamber has seperate smaller chambers to isolate other parts of the circuit too So I m thinking that this unit has to be allowed to warm up for at least 2 hours before everything gets stable Its quite the piece of work every bit as interesting as the R 390A You should see the huge turret switch on the URM 25 s Date Thu 14 Dec 2000 17 19 00 0800 PST From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 URM 25 Stability Actually Roy should have included that as my observation
362. hy does Nolan not recommend a solid state conversion here It looks like the same sort of circuitry here Obviously 5Y3 s are a lot more plentiful than 83 s which makes that conversion less pressing To my thinking one advantage of converting both rectifier tubes to solid state could be insuring balance in both arms of the HV windings The others are immediate startup and significant decrease in heat and energy consumed Am missing something in this line of thinking Philosophically am more interested in preserving functionality of my gear rather than preserving history Date Thu 23 Mar 2006 17 40 54 0800 From Dan Merz lt mdmerz verizon net gt Subject RE R 390 re l 177 question OT Hi there was a substition of ss diodes published in Antique Radio Classified by Alan Douglas for Hickok testers subbing for the 83 As recall a resistor in series with each diode was involved and it was put into a tube base to be plugged in as a replacement l Il try to find the article the index for the 20 years or so issues that have is not good Douglas was quite familiar with the testers and I m sure the sub worked just as well as the 83 Dan Date Thu 23 Mar 2006 22 17 49 0800 From Dan Merz lt mdmerz verizon net gt Subject RE R 390 re l 177 question OT test gear page 134 Hi the substitute for 83 type tube described by Douglas for use in a number of Hickok tube testers used two 1N4007 diodes and two 10 ohm 1
363. iable The other one is an old tube one a Hampden HBT 477 that has a Xtal socket perfet for testing crystals Anyhow only the opinion of and old FA amp Date Sun 15 Feb 2009 15 00 19 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 test equipment question guess I m STILL in the dark ages from 2 to 34 Mc doesn t cover the IF do NOT require an HP 8640B just to replace either the URM 25 NOR the GR 1001A The B amp K Frequency counter does fin have an HP 410B or C don t remember at THIS moment ant a TS 505D U Old Tek scope that can use to ensure the 455Kc IF isn t over done and distorted have difficulties understanding the NECESSITY for all this NEW test equipment for this OLD 50s radio Cecil tell me you NEVER used this old gear to setup an R 390 or R 390A Date Sun 15 Feb 2009 15 04 42 0500 test gear page 183 From Patrick lt brookbank triad rr com gt Subject Re R 390 test equipment question Sorry meant 2KCS to 34MCS that is what happens when you are an old FA Date Sun 15 Feb 2009 20 06 06 0000 From Lester Veenstra lt mO0ycm veenstras com gt Subject Re R 390 Test Equipment Not necessarily improvements in the results but certainly in the ease speed and reproducibility Been there and done that CTM1 and I have to say it was a joy to get do the job with an HP 606 and 5248 In retrospect what would really would like to have had back then would be a synt
364. iate directly to the receiver the second is that the loading of the counter may disrupt the output levels check the frequency on my URM 25 the disconnect the counter for those reasons By the way perhaps we should agree on the setup to measure the sensitivity of the R 390 so we can better compare who has the hottest receiver noticed that I ve been measuring as if the radio had a 50 ohm input and should have been shunting the input with 100 ohms or so to comply with the URM 25 manual Is it fair to say the a R 390 or SP 600 should always be measured with a 100 ohm resistor in parallel with the balanced input test gear page 287 Date Sun 9 Jan 2000 13 04 22 0500 From km1h juno com Subject Re R 390 Signal generator connection questions gt think there are two problems with having the counter hooked up the gt TNSUIS acisodamons For general use with any sig gen that does not have a built in sample port it is quite easy to build an external one in a shielded enclosure Suitable circuits using broadband toroids etc are in various ARRL and other handbooks A suitable directional coupler of at least 10dB directivity should present negligible loading to the thru port The actual coupled signal level is immaterial as long as it is sufficient to gate the counter As has been stated on the list many times shielding integrity is of paramount interest if you want to get down to the noise The more items you add the greater the chan
365. ice as it s a nice competent and fairly compact scope However I ll also recommend another Tek to consider the 7603 and it s siblings Available quite affordably this 100Mhz 200Mhz in some of the sibling series mainframe can be equipped to suit your needs two single trace vertical and one dual time base plug ins are the usual and provide dual trace with all of the usual sweep capabilities Two dual trace plug ins and now it s a four trace scope Replace the plug ins with say a 7L12 and now it s a fine spectrum analyzer capable of audio to microwave work Other plug ins are available to do other neat things Then you can pull the horizontal plug in place one of the vertical plug ins in it s place and have a very accurately calibrated x y scope While not light usually right near 50 pounds it is a one man tote In addition to the more common totable version a rack version is also to be found If you want a cheaper version of the 7603 the military had a stripped version two 65Mhz vertical standard horizontal no on screen digital readout called the USM 281C note the C as it s the Tek version The 281 281A was Hewlett Packard nice but no where the C scope the D is a test gear page 18 lot nicer than the HPs but still no match for the C the D was made be Dumont Obviously being a plug in model if a module fails it can be replaced often cheaper than fixing 465 s while nice do have so
366. ight Next morning found two shorted caps and was a believer Date Wed 7 Mar 2012 20 11 57 0500 EST From Roger Ruszkowski lt flowertime01 wmconnect com gt Subject R 390 Cap Testing Worry not what is in your R390 or R390 A It can all be fixed and returned to service It can be done with a pair you want to use them both at once of mulitmeters and a signal generator The flavor types and calibration are not important All R390 A s were not built equal but they all are of a minimum standard that can be brought back to good performance If they had just spent the extra 2 cents and used some thing better than those cheap brown plastic things passed off as caps Date Wed 07 Mar 2012 20 29 52 0800 From Jim Hill lt JJan 3 cox net gt Subject Re R 390 AN URM 25D Repair Info More Thanks to Bob and others for all the interesting links downloaded them all Dallas also wrote a number of articles for two BCB Dxing clubs which had the publications called DX News and DX Monitor Back when had pneumonia couldn t do much and attempted to repro all issues that contained technical articles discovered you could become winded just operating a repro test gear page 399 machine Dallas had articles on lossless feedback amplifiers plus some receiver mods etc Bob downloaded all of your links Those containing the word index didn t work but the others worked fine cut and pasted so don t think had any typos Ni
367. ight well have a satellite connected local frequency standard that is continuously monitored for drift and error This thing is part of a system that does the monitoring allows for periodic higher level calibration reports it s condition and provides suitable output frequencies for use in calibrating other equipment Nowadays it s unlikely that such a frequency standard it actually sent to NIST for calibration because satellite transfer methods exist This establishes the traceable nature of that measurement The procedures used in frequency measurements are probably not too complicated but if you were to get a signal generator calibrated you will be test gear page 121 paying them to have a trained experienced technician carry out the measurements according to the established procedures Measurement of frequency is easy out to 10 12 or so but that kind of accuracy in voltage and power measurement is not feasible A check of the manual specs on the HP 8640 will show that the accuracy for output level is far lower than for the frequency On Why do we do this Some folks like John KB6SCO are responsible in an organization to make sure things are correctly calibrated The organization s goals and customers require it and he has a full time job making that happen Few Amateur radio stations need such calibration Some Amateur radio folks WANT to know that their quipment is calibrated correctly If a frequency counter is a little bit off
368. ilitary vacuum tube gear undoubtedly is the TV 7D U Because the TV 7 was the standard tube tester used in the maintenances all over the world this tester isn t rare Lookout for the most recent model D Here a TV 7D U in pristine condition http schmid mainz de TV 7 D Ecco Final Ecco 04 jpg No do not sell one test gear page 402 Aug 6 2012 7 45 AM Bob Camp lt ham rtty us gt wrote gt Even in the best case tube testers aren t perfect In this case even less gt so The 392 runs the tubes at 28 volts on the plates Tube testers are gt going to test them with something much higher gt gt Yes do get a tester Better yet get two of them so you have a backup Date Mon 6 Aug 2012 08 26 10 0400 From Robert Newberry lt N1XBM amsat org gt Subject Re R 390 Testing tubes r392 have an EMC 205 tube tester bought so guess its time to figure it out Date Mon 06 Aug 2012 11 10 14 0500 From Randy and Sherry Guttery lt comcents bellsouth net gt Subject Re R 390 Testing tubes r392 have a different opinion on this while the TV 7 series is indeed a fine tester and period correct for much military vacuum gear it is by no means the most on several counts In my opinion the TV 3B is far more collectible as a period piece and certainly as competent as a TV 7 for most early military tube gear With it s built in Multi meter and hidden power cord compartment it s coolness factor is almos
369. info to contact Wendell E Hall who still repairs them try Bill Waters wate juno com who services Hickoks and has a ton of replacement parts and tube data See http www vacuumtubes com specifiacally http Awww vacuumtubes com manuals html He offers the lates Hickock roll chart in book form for 15 From AL MANHAN lt capt al verizon net gt Date Sun 23 Mar 2003 11 21 55 0500 Subject R 390 Re R 390 digest Vol 1 622 10 msgs test gear page 79 You can find all the original HP manuals at Consolidated Surplus cs usimperio com A little pricey but available From toburr dixie net com Date Tue 8 Apr 2003 09 03 10 0500 CDT Subject R 390 Suggested Test Equipment for R 390A Alignment Can anyone suggest recommend a good basic list of test equipment to check the operation of the R 390A Is the AN URM 25 absolutely a must or can anyone recommend a specific substitute type signal generator have two R 390A s in storage that were operational years ago and want to get them out put them to use If my back does not give out on me plan to be asking a lot of stupid questions in the future so please do not be too harsh on me am not a tech but am sincerely interested in learning about the R 390A Date Tue 8 Apr 2003 09 11 51 0500 From mikea lt mikea mikea ath cx gt Subject Re R 390 Suggested Test Equipment for R 390A Alignment ISTR people swearing by and some swearing at
370. ing a URM 25 56 years old because it doesn t do alinement tests or whatever to current standards pays no respect to history Vintage Used for R 390 s it s perfectly satisfactory why you can align a R 390 using the calibrator if you read the manual and have your druthers about you Any noticeable useable improvement using later sophisticated gear is fetishism to extreme lengths get real Date Sun 15 Feb 2009 12 22 01 0500 From Bob Young lt youngbob53 msn com gt Subject R 390 backlash on URM 25 test gear page 369 My URM 25 bought from a vendor who sells them on epay it came with some back lash and it has gotten worse have tried the fix making the gears tighter with the adjustment and it helps but there is a point of diminishing returns where it gets so hard to turn that it is useless even sent it back once after shorting out something from my fix and got congtatulated on my fix or in other words don t send it back to us haha This is the only flaw I ve found the backlash is terrible on high frequencies so guess will be looking for a better frequency generator or another one without backlash Date Sun 15 Feb 2009 15 48 08 EST From Flowertime01 wmconnect com Subject Re R 390 backlash on URM 25 You may be going the wrong way with your back lash My recollection from the late 60 s early 70 s was the generators always had some back lash You just could not roll up on a frequency and then expect to jus
371. ing and the cap rotor and stator are now rubbing gt The modulation still works For now The D model is susceptible to modulator failure The cause is drifted resistors and or leaky capacitors paper most likely in the bridged Tee circuit in the oscillator Dallas Lankford wrote a multi page description of how to overhaul the D model while he was editing Hollow State News The HSN publisher can still supply a paper copy of that think also that it has been transformed into digital form but I m not sure of it s availability No owner of a URM 25D should be without one He does not deal with the tuning mechanicals Also he did not write a similar one for the F model gt Worst of all a little set screw fell out of it or it was a huge gt coincidence and can t figure out where this came from Anyone have any gt ideas or does anyone know a place where can get this reconditioned Do you have the errant set screw If you report the size of the thing it may help locate the place it belongs It may well be left over from years ago and there really is no missing set screw There has been one person who worked on these things and has sold refurbished ones on ebay or mailing lists Can t remember who That may be in my notes file Date Mon 22 Oct 2007 12 02 41 0700 From Brian Bjerkelund lt k7ais msn com gt Subject Re R 390 speaking of AN URM s Roy and group That would be cornelius_connie ebay id have no connection or
372. ing data etc I m debating on possibly taking the data once it s all typed in and well checked for errors and putting in into a database format with a nice little search interface The killer is the initial typing of the data After that cut and paste will be REAL nice Also the next project will be an electronic version of the TV 7 series tube tester data had originally planned to do it before the TV 2 series roll chart but my response for supplements and changes to the 1962 manual really sucked so I m still in the information gathering stages for the TV 7 testers If you go to http www acadiacom net nlee tv 7_ index html you can see the TV 7 source material that I ve got need a mess of missing supplements to the 1962 11 6625 274 12 1 manual don t want your originals Sharp clear photocopies are fine Even though the I 177 series project is finished I m still looking for manuals or supplements other than the dozen or so that used to create the Excel file for it A list of the manuals that used is available at http www acadiacom net nlee i177_index html along with the actual I 177 settings data file think that there s a total of 3000 or so lines of settings data in it for using the I 177 series both with and without the MX 949x adapter box Date Sun 13 Feb 2000 18 44 49 0500 EST From Norman Ryan lt nryan duke edu gt Subject Re R 390 Wtd TV 7 info The best thing you can do for your TV 7 bar none is to
373. ing received from the TV 7 man Hope this helps From Daniel Nelson mailto djn ieee org Sent Thursday July 07 2011 8 43 PM To Foster Subject RE R 390 TV 10 Lid Gasket do not have any original gaskets make them up with a 1 4 half round gasket get from a local Auto supply store Hope this helps Regards Daniel Nelson djn ieee org Date Wed 7 Dec 2011 11 29 13 0800 PST From John Flood lt kb1fqg yahoo com gt Subject R 390 TV 7 meter needed Ok when you all stop laughing do need one My movement is hanging up got it working better than it was but I ll be needing a replacement see them from time to time on epay but wanted to check here first lt snip gt test gear page 377 Date Thu 08 Dec 2011 07 36 57 0600 From Jerry K lt w5kp hughes net gt Subject Re R 390 TV 7 meter needed John check this lt http www gvtc com Eedengel TV7Meter htm gt out for a slick idea for replacing the TV 7 meter plan to try this if mine bites the bullet hacking a DMM for use in a TV 7D ed Date Thu 08 Dec 2011 08 57 21 0500 From k2cby lt k2cby optonline net gt Subject R 390 TV 7 Meter had a TV 7 meter problem some years ago The cause turned out to be the little electrolytic that s hung across the meter terminals which had failed open By the time traced the problem the meter movement had gone west from oscillating back and forth and had to be replaced discovered that t
374. ink bought my buddy lunch for testing it for me I ve got a recent 1990 s ten digit Racal Dana counter and a 1970 s vintage SD counter that dropped off to him Both have optional high end time bases that still easily exceed the original specs All had him do to each of them was run them for a week and tweak the oscillator in each to the facility s standard Total cost of two cases of cheap American beer With the basics of resistance voltage and time covered can calibrate just about everything else that need to use It still amazes just how basic the three requirements are when you think about it Date Fri 15 Dec 2000 10 25 53 0500 From Al2Q Alex lt ai2q ispchannel com gt Subject R 390 Instrumentation blues All this talk on the thread about URM 25s mine is exceptionally stable and certainly worth the 20 paid for it got me thinking again about one of my favorite instruments a 1954 vintage Weston Model 785 Type 6A Industrial Circuit Tester which is a VOM It s a beautiful metal encased instrument with a black engraved bakelite front panel complete with impressive machined meter shunt and accompanying foot square hardwood carrying case It hails from the same era as my beloved Motorola R 390A receiver which also carries a date tag of 1954 had been using it as my reference standard whenever calibrating meter circuits in the shack etc but the bobbin seems to have opened up tested the movement s resistance an
375. into private mode with a very limited membership It is a shame was really enjoying his work on antennas Norton pre amplifiers and BCB expeditions Date Tue 06 Mar 2012 16 12 06 0500 From rbethman lt rbethman comcast net gt Subject R 390 HSN Docs The following are being posted to MY site for a month or two Another list member provided them to me with the intent that load them on my site This should be more than adequate for folks to get a copy of am NOT going to become an Edebris don t have the time nor the patience for such not to mention the site space However do my best to assist the list Here s the list HSN Accessories pdf HSN Accessoriesindex pdf HSN Hammarlund pdf HSN Hammarlundindex pdf HSN R390 pdf HSN R390index pdf HSN TestEQ pdf HSN TestE Qindex pdf Best of Hollow State by Reid Wheeler doc Each of these is preceded by lt lt http nome comcast net rbethman gt am going to load them right after this is sent Date Tue 06 Mar 2012 16 31 23 0500 From Jim lt jbrannig verizon net gt Subject Re R 390 Hollow State News Index have an 11 page pdf titled URM 25D Maintenance Notes Dallas Lankford Nov 1988 If anyone wants a copy e mail me Date Tue 06 Mar 2012 16 46 33 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 Hollow State News Index test gear page 390 That is part of the zip file that posted earlier It resides within the zip file alon
376. it often interferes with sensitivity measurements There is a reason that re furbished and guaranteed 8640Bs are so pricey they still outperform almost everything else in several key areas But most of us don t buy them re furbished and guaranteed so we don t pay nearly that much for them I didn t pay 200 for any of mine Date Wed 12 Jan 2011 07 42 49 0800 PST From Rasputin Novgorod lt priapulus yahoo com gt Subject R 390 HP 8640B usage Thanks to eBuy and other sources have some beautiful and functional HP test gear that used to only dream of having Unfortunately though have theoretical book knowledge of it s usage I ve got very little practical experience test gear page 236 Right now have an active HF antenna amplifier splitter multicoupler one antenna to several radios that died and I m trying to fix The power supply is good I d like to connect my HP 8640B to the antenna input then trace the signal But have no idea for the power level to set the HP 8640B to Indeed I d be very grateful if someone could suggest all the HP 8640B settings for this to reduce my chance of coming to grief Date Wed 12 Jan 2011 10 59 40 0500 From Roger Gibboni lt rgibboni dulye com gt Subject Re R 390 HP 8640B usage Set the output at 10 dB above the sensitivity of whatever you are using to trace the signal Spectrum analyzer receiver Date Wed 12 Jan 2011 11 29 57 0500 From Jon Schlegel lt
377. it works fine Date Wed 03 Jan 2001 17 22 52 0500 From Phil VA3UX lt phil vaxxine com gt Subject Re R 390 R 390A Manuals and O Scope Both good recommendations Jerry Both are relatively cheap now and are good performers Anything by Tek is good and nearly everything by HP is good too Bear in mind that neither company supports the older instruments anymore You should be able to get decent 100 Mhz scope for 100 to 200 on eBay I m referring to the Tek 45X series Date Wed 3 Jan 2001 19 33 45 0500 From Barry Hauser lt barry hausernet com gt Subject Re R 390 R 390A Manuals and O Scope Anybody have any experience with the Tek 564 storage scope Don t ask me why I m askin Oh well if you insist paid 50 bucks including manuals for the mainframe and two plug ins plus a probe some time ago It s been waiting for me to do what I m not sure maybe to capture a plot of my EKG for posterity before flatline also have a matched set of Tek Electroluxes T 922 s plus the rack mount version which the gov t saw fit to buy at one time My understanding is that these are not exactly the pinnacle of Tek s past product line Also the blue ones don t have much suction only about 15 mhz worth test gear page 23 At least the knobs aren t broken on those have a couple of HP s a 100mhz 1701B and a 200mhz 1710B of more recent vintage but the triple concentric knobs are broken These weren t abu
378. ith it By the way if you do this and keep a pile of the capacitors you have pulled out and replaced you will find that 99 if not actually 100 of them test good and the others are passable for non critical applications If you are determined to use a capacitance checker the Heathkit IT 11 is test gear page 393 about as good as it gets Stay away from the CT 1 it s not very useful My next choice would be the EICO Model 950B R C Bridge It is about the same as the Heathkit IT 11 but not quite so fancy and not as easy to use but usually a lot cheaper Next on my list would be the military ZM 11 U and finally the ZM 3 capacitor analyzer This is the cr me de la cr me of 1950 1960 capacitance testers Caveat Both of the latter two are R 390 vintage tube type equipment test instruments they are SUPER on tube type equipment but aren t very helpful for solid state electronics especially electrolytic and tantalum capacitors built to modern specs I ll withhold comment on the Sencore instruments since I ve never used one Date Tue 6 Mar 2012 19 58 48 0600 From chacuff lt chacuff cableone net gt Subject Re R 390 Capacitor tester John I m a firm believer in using a cap analyzer in tube radio work The cap really needs to be tested at its rated voltage for leakage current have been using the Sencore products for years The LC 53 LC 73 and currently the LC 102 They work great A bit pricey at times
379. ith wiper fingers Round holes leak less than slots test gear page 318 Improving stability is harder The band switch or turret contacts are a big problem That s one of the fundamental ways the R 390 a is so much better than a Hammarlund or Hallicrafters of similar vintage The variable frequency oscillator has no band switch contacts The only contacts are at the crystals and in far less critical gain stage tuned circuits Crystals band switch with lots of variation in contact resistance without a significant change in frequency One of the fundamentals of stable oscillator design is to minimize tuning range and keep most of the tuned circuit capacitance in stable fixed capacitors But that s in conflict with a wide tuning range on each band So most of the tuned circuit capacitance is in the variable capacitor which makes stability very much dependent on the quality of the capacitor and its rotor contacts Good oscillator circuits use large valued feed back capacitors Colpitts circuit to swamp tube capacitance changes with a small coupling capacitor to the tuned circuit Often signal generators because of their wide frequency range use a tapped coil Hartley circuit That makes it harder to isolate the tube from the tuned circuit If the grid C is isolated with a small coupling capacitor the cathode tap has to be moved and is always a compromise to keep the oscillator level reasonably flat across each band Sometimes the compromise is just to
380. ive but I m not sure what it is used ODs and dipped silver micas caps The only two fixed caps did not replace was a coupling cap and a bypass that was made like a little stand off insulator common style in those days suppose Is this sort of temperature sensitivity normal in a simple circuit can breathe on the R390A all want and it isn t affected Once the thing is sealed up and in the case won t be able to breathe on it so this problem won t exist but was left rather curious about what could cause this kind of sensitivity This generator uses a large variable cap to change frequencies Would the capacitance of this component be that sensitive to temperature changes wouldn t think so The grid tanks are comprised of a slug tuned coil and a ceramic trimmer for each band Would these be suspect The temperature sensitivity isn t isolated to one band so it seems to point to a common component Any thoughts Wish had a schematic to share Date Thu 14 Dec 2000 08 50 44 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 URM 25 Stability gt To state it a different way the drift is 100hz per minute think that his drift problem is only during the warm up period If not Joe s got problems gt My 25D is stable enough at low frequencies Mine too gt At progressively higher frequencies it is less stable cccceeeees I ve never tried using
381. ively It starts out a little high goes low briefly then back to high until nearly the upper end where it crosses back to low again Not sure if this is the best way to do it but it does get me closer know the R390A s IF transformers are peaked something like this not at the endpoints but somewhere near the end Maybe this is good for calibration procedures as well Hope this isn t too OT for this reflector Date Sat 1 Aug 2009 12 18 56 0500 From Tisha Hayes lt tisha hayes gmail com gt Subject R 390 Tuning linearity The deal with the HP 606A sounded like an interesting challenge think your solution would be very applicable in many radios other than in a permeability tuned radio such as the R 390A and most vintage car radios As most know we can adjust the linearity of an R 390A tuning through the compensator disc and it s million tiny screws on the PTO If you have ever chased the tuning on a radio that was wildly out of alignment you know that you can get what appears to be decent spots As a youngster had a Soundesign clock radio that could barely pick up WLS Chicago at night decided to tune it up and as a bit of a neatness freak throught that those little yellow red and green screws on the metallic tuning cans should really all be tightened down snug Then tried to tune the radio with the two or three tiny little capacitors on the back of the main tuning cap After a bunch of misguided tweaking and pure
382. ize damage see the electrolytics that you mentioned mean just barely see them Just how does one go about changing them That module has to come out of there is there a tried and proven method There s a BIG one w a a ay down in there near the bottom gt Fair Radio used to sell the attenuators for 20 or so don t know whether they still have them l Il find out gt If you have to rebuild it finding resistors is going to be interesting Getting them in there is too Date Sun 3 Oct 1999 19 31 53 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 Yeah just got me a URM 25 D Got em Roy Just hadn t gotten to reading them yet see what you re talking about they re as good as the manual big help But taking the Buffer Amp out still looks like a bear This unit was built think in 1962 and still has the original tubes in it Of course the inside looks new and it seems to have been taken care of except for having had its rubber feet removed I m wondering if the caps are going to be a problem at all see NO Evil Caps i e Black Beauties of Death etc Just electrolytics Date Tue 5 Oct 1999 19 15 43 EDT From SBJohnston aol com Subject Re R 390 Yeah just got me a URM 25 D test gear page 271 gt It HAS to be terminated with the 50 ohm load which don t have yet You can use a BNC T connector and a 50 ohm BNC terminator as intended for 10Base2 thin net ethern
383. ked it against WWV and it was off by 1852 Cps after being used for 15 years Not to shabby Because of its name and funky rf patch panel inputs almost no dealer or epay surfers know what they are good for This of course makes it a good buy for the BA crew Here is the icing on the cake free operators manual written by Bill Feldmann N6py on the BAMA site as well as the service manual is available from several sites got mine from the W5JGV website These are BIG files Volume 1 is 113Mbytes ZIPPED It took me all night do download it on dial up Bill s operators manual is far superior to the HP one which assumes that you have an EE degree from MIT Just Kidding HP has kindly given permission to reprint its material Also it looks the US military used a bunch of these Last but not least the unit weighs 40 something pounds and takes up almost the volume of one of are beloved receivers No rice box here got mine from a company on epay called atvm in MD which usually sells Mercedes Benz parts VERY well packed UPS couldn t screw it up a pleasant change They still are selling some under receivers Even if they sell out this unit will show up from time to time Download the operators manual from BAMA and see all the good stuff this thing can do Good scrounging Perrier Date 21 Mar 2006 14 06 12 0000 From n4bug knology net lt n4buq knology net gt Subject R 390 HP410B rectifier tubes Many of you own the HP410B VTVM and us
384. kes clinging to the back of the panel but none near the switches managed to fix the problem false short reading in position 5 on the shorts test switch But suspect that wasn t the switch at all more like shorting under the 7 and 9 pin tube sockets However do have a switch issue On the rotor contacts of most of the switches and smeared on parts of the ceramic wafers was this black stuff that looked like graphite lubricant The design of the wafers is such that it was unlikely to cause shorting there are deep grooves in those wafers that accommodate the stationary contacts It seems as though the undersides of the rotors were coated with the stuff It cleaned off fairly easily but consumed a lot of swabbies Funny thing though the stuff turned the swabs black but it wouldn t come off on my fingers the way most goopus will At first thought was silver oxide or some kind of oxide but no Anyway DeOxited the switches as best could with the swabs mostly relying on coating the rotor metal and working the switches Although it might be safe enough to spray DeOxit on ceramic switches they re just too dense in there and it would make for a drippy mess Before did that blew out the works with compressed air Now for what looked like the real problem which suspected from the start The TV 7D U has ferrite beads on every tube socket terminal Normally at least from what know ferrite beads are placed on insulate
385. knowledge on this outfit test gear page 368 Date Mon 22 Oct 2007 12 13 36 0700 From Kenneth G Gordon lt kgordon2006 verizon net gt Subject Re R 390 speaking of AN URM s Yes That is the one Connie is very capable honest and thorough She routinely sells URM 25s and other like items on the bay sometimes have heard nothing bad about her at all from any source Date Thu 6 Nov 2008 19 08 24 0800 PST From David Elsea lt dkelsea sbcglobal net gt Subject R 390 sg 103 Is the SG 103 URM 25F the same thing as the AN URM 25F They look the same Can t seem to find anything on the SG 103 however it brings alot of an urm25f hits on google Just wondering Dave Date Thu 6 Nov 2008 22 29 18 0600 From Tom Norris lt nu4g radio gmail com gt Subject Re R 390 sg 103 Yep best as can tell have an SG 1 which was navalized by painting it gray over a flawless silver gray hammertone dangit and stenciling URM 25 on the back and sides The front is brushed chrome and hard to read but is calibrated perfectly It was the civvied up version of the URM 25 by the same contractor that was on the Navy tag whom forget By bet is you ll be hard pressed to find any differences in yours and an official URM 25 other than possibly two tags Date Sun 15 Feb 2009 11 28 40 1100 From Pete Williams lt jupete bigpond net au gt Subject R 390 Test Equipment G day well for goodness sakes guys belittl
386. knuckles came into contact with the lugs managed to skin my knuckles quite nicely Pain ensued as well as some conversation with the meter which I m sure it didn t understand but it helped me feel better anyway resorted to tapping the ring back into place with a hammer and large screwdriver I know a screwdriver isn t a punch but don t have a nice assortment of punches At any rate it tapped back into place rather easily with no more lost flesh on my part and no damage to the meter put it back together and it is working smooth as ever test gear page 65 Subject Re R 390 Need Meter Repair Help From Roger L Ruszkowski lt rlruszkowski raytheon com gt Date Fri 8 Mar 2002 09 47 37 0800 Yes there are spanner tools to do it a 1 x 2 pin stake Drill two holes in the stake with 4 penny nails at the correct span to fit the ring Grind end of 4 penny nails to fit the slots in the ring OR You can put a pin punch against one of the slots and tap the ring loose You will want to grip the meter in a big bench vise if you can Just a challenge in tools Tim Allen never addresses these real life problems From N4ue aol com Date Sun 7 Jul 2002 16 27 42 EDT Subject R 390 no subject Dallas this is excellent information on the R 390 can t wait until my new home is done so can git back at it One question for the group just acquired a nice HP 410C but natch the RF probe was missing Any good inform
387. l If you use the digital multimeter in the voltage mode it will indicate very low currents Put it on the scale high enough to measure the voltage of the power supply you have Lets say that is the 1000 volt scale The input impedance of the meter is likely to be 10 meg ohms you should check this So if it reads one volt that means one tenth of a microamp Just test gear page 273 hook the capacitor from the DC supply to the plus lead of the voltmeter the other lead of the voltmeter goes to ground or negative of the B supply Watch the voltage decrease down from some high value toward zero as the capacitor charges up When it gets done decreasing you have your leakage current in tenths of microamperes The actual voltage on the cap under test is the difference between the supply voltage and the voltmeter indication but that likely will not matter at all If you want to measure the current in microamperes just put a one meg ohm resistor in parallel with the voltmeter 11 10 megohm for better accuracy Newly made film caps will measure nearly zero Old leaky paper caps will often measure half of the supply voltage or more Cap eat emptor Roy Who has two SP 600 s and two URM 25 s waiting for new caps Date Sat 1 Jan 2000 12 18 01 0500 From km1h juno com Subject Re R 390 Signal generator connection questions Hi Jerry and the group woke up this AM and found the planet still in one piece use both a URM 25D wi
388. l com Subject Re R 390 URM 25 Stability Place it on a very sturdy table bench test gear page 316 Date Fri 15 Dec 2000 19 47 43 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 URM 25 Stability gt Do you have any suggestions to reduce the leakage on an old URM 25 If was going to aim for the least possible RF leakage from a 25D G H the first thing I d do is replace the internal coax lead from the casting to the attenuator with a the best shielded coax could find Maybe even some type of semi rigid copper tubing outer covering like is used in microwave applications The next step would be to put a BNC caps on all of the unused BNC jacks on the front panel Next I ve verify that the internal cover on the attenuator is fully seated along it s circumference I d look at possibly adding finger stock or copper screening along the perimeter of the front panel where it slips into the main cabinet The step would probably be a pain in the ass but I d verify that the cover of the cast housing screws up dead flat against the main housing You can verify that the inner walls mate with the cover with plastigauge If it isn t then a machinists straightedge would let you know if the cover was at fault or the main casting If it was the cover a little time spent on a lapping block would fix it If the main casting was the problem you have to remove whatever components that would prevent it from lying flat on the lapping
389. l iaxs net gt Subject RE R 390 recommendation for rf signal generater Fair Radio used to have URM 25x attenuators at a reasonable price They have excellent shielding and can be used easily in the configuration John describes The one got only had one overheated resistor in it Date Thu 6 Sep 2001 03 16 19 0400 From Tom Leiper lt twleiper juno com gt Subject Re R 390 recommendation for rf signal generater On the counter ary with the URM 25 you can use the high power output with a series resistor of value in my case is 50K to just allow the counter to work reliably which has almost no effect on the calibration of the padded adjustable output How many of your modern sand state generators have TWO outputs huh Take THAT you sniveling snide assed silicon valley girls wherever you are Date Thu 6 Sep 2001 21 22 07 0700 PDT From John Kolb lt jlkolo cts com gt Subject Re R 390 recommendation for rf signal generater gt On the counter ary with the URM 25 you can use the high gt power output with a series resistor lt snip gt Ah can t do that with my HP606 or Logimetrics generators Remember though it s important to keep good shielding between the sig gen and the counter and the attenuator ended up using coax with two layers of shield when needed to make critical measurements Otherwise the high level output would leak enough out through the braid and be picked up directly by
390. l in love with the 606A on your journey to upgrade now use the 8640B which is the cats meow There are a lot of other signal generators that fill the bill as well Date Tue 18 Jan 2005 02 22 13 0800 From Dan Arney lt hankarn pacbell net gt Subject Re R 390 HP 606 vs URM 25 Glen have all of them plus the 8660C which is the Tiger of the bunch for sure Date Tue 18 Jan 2005 08 00 58 0500 From B Riches lt bill riches verizon net gt Subject Re R 390 HP 606 vs URM 25 uses both when was in the Air Force in 1960 Both good units but wait until you use the 606 great generator Congrats Date Tue 18 Jan 2005 07 27 35 0600 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 HP 606 vs URM 25 I ve had both and liked the 606 much better so much so that gave my URM 25 away The 608 is a great machine as well especially the E model now use an 8640B but still Keep the 606 on the bench as well and use it often Date Tue 18 Jan 2005 12 13 46 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 HP 606 vs URM 25 The synchronizer was not required The B version of the generator had very few differences compared to the A The ones that can think of are facilities to use the synchronizer DC voltage output proportional to the dial setting a variable capacitance in the oscillator L C circuit and input output connectors for the needed signals t
391. last place it was test gear page 217 at The 8640Bs were all together something different suspect that the issues regarding the gears was some management decision to do things on the cheap Lord only knows what else they did that way Date Sat 20 Feb 2010 09 29 08 0800 From Jeff Anderson lt jca1955 sbcglobal net gt Subject Re R 390 HP 8640B Question Know of a couple of reasons why an 8640B might be showing all zeros The first is very simple There s a switch on the back panel that allows the user to select between an external frequency reference and the internal frequency reference If it s in the Ext Ref position and there s no reference attached you can get an all zero display An all zero display can also be caused by moisture in the oscillator cavity if I m remembering this correctly Apparently this can lower the Q to such an extent that the oscillator no longer oscillates for example if the display goes to zero while you re changing frequency this might be the cause The fix for this involves pulling out the cavity assembly removing a plug on it and then putting the assembly into an oven for a period of time to out gas the moisture Date Sat 20 Feb 2010 11 38 02 0600 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 HP 8640B Question Nope the display should show the current frequency being generated if it s all zero s would say there is a problem Mine comes up co
392. ld on whatever frequency left it on plus or minus the warm up drift If the lock button is depressed it will go straight to a flashing display indicating it is out of lock which is common while warming up Even then it s not all zeros Date Sat 20 Feb 2010 13 41 50 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP 8640B Question test gear page 218 If they are treated carefully proper mechanical maintenance and no manhandling of the controls and not subject to temperature extremes they are not so failure prone assume that ome nylon gears were made better than others better and worse days at the gear factory so some are inherently less failure prone Plus HP made an enormous number of 8640Bs so even large attrition leaves lots of them in service The problem with a fix is that since there are so many of them professional industrial users can just get a working unit from a reputable equipment vendor The broken ones go to hobbyists who won t pay 200 for parts to fix them gt doubt spectral purity is all that critical 00 No argument there For those of us who use a generator to aid in designing low noise low distortion amplifiers and mixers it can make quite a difference Date Sat 20 Feb 2010 10 50 19 0800 PST From Kim Herron lt kim herron sbcglobal net gt Subject Re R 390 HP 8640B Question The display will come up all zeros when the internal external switch is
393. le won t use a VOM to measure AGC voltages Most VTVMs have a constant 10 or 11 Megohm input impedance HP is 100 Megohms while the input impedances of VOMs vary with range and price and are usually far less than this This lower impedance can load a high impedance circuit and pull the voltage down producing an inaccurate reading Also most VOMs are easily damaged if overloaded and many will not survive being dropped Most modern DVMs have a 10 Megohm input impedance similar to a VTVM Thus these can be used in place of a VTVM and will usually be more accurate as well VOMs are still sold by Radio Shack and others and are still not a good choice for BA work I ve used many types of DVMs and most were more than satisfactory Any name brand DVM should serve you well Price depends upon accuracy and features most any DVM will make adequate BA measurements so let your wallet decide One caveat many radios have impedances on the order of one Megohm in their AGC circuits In these circuits 10 Megohms can be a significant load This is usually not a problem since AGC voltages can vary a lot just due to differences among vacuum tubes If you need to measure accurately in these circuits consider using a 90 Megohm resistor in series with your probe or use a high voltage probe which is also a series resistor to raise the input impedance Remember to correct for the voltage division that this creates Also lab grade DVMs are available
394. least noisy tubes closest to the antenna You ve brought up an interesting idea here I ve never bothered to test tubes for noise other than tapping on them and looking for either the shorts light to flash or the meter to drop in the tube tester Anyone have a good method to actually test tubes for noise don t mean loose elements or microphonic etc mean normal integral noise We know that it varies from tube to tube I ve never tried it but what about using a scope on a tube while in the tube tester gt At the end of the day it does not matter what measurements on a 30 year gt old tube tester tell you You cannot connect an antenna and speaker to a gt tube tester Only performance in the real radio counts True but that 30 year old tube tester can alert me to shorted elements in the tube or gas etc before install it in the receiver I ve found that the gas test is important and often overlooked by people I ve had some really quirky problems over the years that ended up being gassy tubes Especially in the AGC circuit of the R 390A Date Sun 11 Mar 2001 14 38 06 0600 From Nolan Lee lt nlee gs verio net gt Subject R 390 TV 3 amp TV 10 tube testers update The data collection continues for the TV 3 TV 10 knowledge of the ancients project just updated my TV3 TV 10 page at http Awww acadiacom net nlee tv 3 amp 10 html with the data have accumulated so far and what I m still looking for I ve laid out
395. least that was what read on one of these lists awhile back gt gt gt gt And more attenuation stages in it Date Mon 22 Oct 2007 09 01 41 0700 From W6GER lt w 6ger uci net gt Subject R 390 RE AN URM 25 Richard you can download manuals for the URM 25D amp URM 25F from The BoatAnchor Manual Archive BAMA at http bama sbc edu military htm Date Mon 22 Oct 2007 13 43 55 0400 From Bob Young lt youngbob53 msn com gt Subject R 390 speaking of AN URM s My AN URM 25F has always has severe backlash since bought it took it apart and found an adjustment that should have taken care of it it presses the worm gear against the round gear driving the variable cap It was not even touching so adjusted it down a little bit put it back together and have no RF output now all tubes are good can t see where did any damage the modulation still works Worst of all a little set screw fell out of it or it was a huge coincidence and can t figure out where this came from Anyone have any ideas or does anyone know a place where can get this reconditioned Date Mon 22 Oct 2007 14 26 05 0400 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 speaking of AN URM s AH The dreaded worm gear heheh NOTE the D and F model have different drive mechanisms if remember right The F model is quite similar electronically to the D but quite different mechanically Backlash in the D model can some
396. lieve they are that beloved worldwide though since those things have been dropping like flies from the same ailment for years now and nobody has bothered or paid the to come up with a fix for them like a new set of replacement gears You can bet your bippy that Agilent isn t the least bit interested in providing a cheap sensible fix for dying 8640B s they d be tickled silly if they ALL ended up in a landfill doubt spectral purity is all that critical to running an alignment signal through a 50 year old vacuum tube receiver anyway which is 95 of what do with my generators Heck I m happy to just FIND a signal at the other end of an RF deck or an IF strip sometimes spectrally pure or not Date Sat 20 Feb 2010 10 46 03 0600 From Barry lt n4buq knology net gt Subject Re R 390 HP 8640B Question I m curious about something Many of the 8640Bs see display all zeros apparently on start up Some of the ads state the display simply shows all zeros apparently even when the frequency change knob is exercised Is this a common Is there something one has to do to get the frequency to display Date Sat 20 Feb 2010 12 13 06 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 HP 8640B Question Barry Not owning one nor having the manual s couldn t tell you have older HP gear A 410B and a 312A One is analog all the way the other uses a nixie tube display that always comes up displaying the
397. like to mess around inside our gear without having the manual handy got a very nice reprint from Robert Downs Cost exceeded the TS s but was worthwhile for peace of mind alone Main reason for acquiring the manual was for having calibration instructions at hand Turns out this chore is a piece of cake Here s how to calibrate any model TS 505 DC ZERO DEFLECTION Open the meter and after warmup adjust for DC Zero Deflection as follows 1 With FUNCTION switch turned to DC set ZERO ADJ control on front to its mid range Leave it there throughout all the following procedures 2 Short together the DC and COMMON probes 3 Set RANGE to 2 5V Rx1 position 4 Loosen locknut on R18 pot and turn gradually to suit This is a rheostat wired in series with the filaments of tubes V1 and V2 that causes the meter to come around slowly If you run out of range try reversing tubes V1 and V2 Wait at least a minute for the meter to settle as close to zero as possible Fine tune with the ZERO ADJ control 5 Tighten R18 locknut and verify meter pointer is still on zero DC FULL SCALE DEFLECTION 1 Keep FUNCTION and RANGE at above settings and loosen R10 locknut 2 Apply 2 5 VDC or 1 across DC and COMMON probes and adjust R10 for full scale reading Wait and watch for one minute 3 Lock R10 verify meter reading then disconnect probes from DC source DC ZERO CENTER SCALE 1 Turn FUNCTION to DC position Short DC and COMMON probe
398. lipping collars as well have a pile of them here that folks know bought on eBay hoping they had good gears and not one of them works due to gear failures probably 3000 worth of eBay mistakes in one pile Some of them have other problems as well Personally would not risk buying any 8640B had not personally seen and played with have repaired several gears with split collars by machining new brass collars and attaching them to the existing Nylon gear flanges have threatened to machine new large gears out of brass but have not done so as yet Maybe when retire test gear page 214 Date Fri 19 Feb 2010 07 14 42 0600 From Jerry K lt w5kp hughes net gt Subject Re R 390 HP 8640B Question went through two 8640b s several years back and ended up with the same gear and output attenuator problems as everybody else before threw up my hands and bought a clean used HP 8656B from a defunct New York TV studio no less and it has been the best test equipment money I ve ever spent Even though it s relatively old technology it s like stepping up from a Yugo to a Lexus for receiver work when compared to the 8640B especially like being able to quickly program sets of IF and RF alignment freqs and output levels for a bunch of different receiver bands and recall any of them instantly with a couple of button punches during an alignment procedure That is a HUGE time saver for bench work on R 390A s and such hate
399. lists and news groups and selectively strip them for the parts that people need to restore theirs and offer them at reasonable prices lt subliminal message on gt Keep me in mind for a 547 CRT a matched pair of nuvistors out of the front end of a late model 503 a diode risetime plugin a transistor risetime plugin and a couple of manuals I m missing lt subliminal message off gt gt have about 150 000 tubes but guess could pull those if they have value It s sad but that s where the money is test gear page 36 gt That is unless you have something better to suggest Hey drop a note to Stan Griffiths at w7ni teleport com He s a hell of a nice guy and has regular contact with probably the greater majority of 5xx scope fans on the net think that he s still running a discussion group on his website You should be able to find other Tek collectors looking for parts there He s sharp as a tack at running down problems too gt hate to do it but am hurting for space gt And of course cannot store them in my 2 car garage either as we gt have not had any cars in there in about 8 years Cars in a garage Why lt grin gt can t remember the last time the wife could park a car under cover Come to think of it in over twenty years she hasn t need more space Date Sun 22 Oct 2000 19 51 40 0400 From Al Solway lt beral videotron ca gt Subject R 390 Signal Gen HP8640B and HP8640B W OPT 323 am lo
400. little better dynamic range have looked on the web and can t find information on the differences Would any of the users of this list know any differences off line or not Perhaps the B model uses better FET s in the front end The A model seems to be very available and the B model a little harder to find am wondering if one were to buy the A model could it be upgraded to the B by changing out a few parts Any help will be appreciated Date Wed 12 Jan 2011 13 57 43 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 Spectrum Analyzer They are both great machines if you don t need to go above 40 MHz The primary differences are the display and control functions and other microprocessor circuitry For example the A has its reticle grid on the CRT while the B generates it with the electron gun They have a different set of GPIB commands as well Functionally they are peas in a pod have never noticed any difference in DR but there may be one Certainly have never needed anything better in that regard than an A The B models were not made for nearly as long as the A s which accounts for the present difference in availability gt if one were to buy the A model could it be upgraded to the B by changing out a few parts No In fact some A modules will not work in other A s of different eras For this reason one has to be careful when acquiring spares Date Wed 12 Jan 2011 20 09 57 0800 PST From
401. ll them for cost including shipping and taxes from Mouser plus postage plus 20 in blocks of 25 Your savings will be about 50 of the single unit price To make this work I ll need a commitment of 500 minimum The HP 5370B uses about 46 If enough people are interested am willing to make a group buy in blocks of 100 The capacitor is a Panasonic 105C 6 000 Hr P N 667 EEU FR1H151B am willing to sell them for cost including shipping and taxes from Mouser plus postage plus 20 in blocks of 50 Your savings will be about 50 of the single unit price For this to work I ll need a commitment of 1 000 minimum Parts will be cash up front If you do the math you will see I m better off working for Mickey D If interested PLEASE send me an ORIGINAL email off list inform everybody by email if it is a go Some have not been doing this and it screws up my Yahooey mail and may miss your order test gear page 413
402. loating floors anechoic coatings etc Hard to imagine anyone doing similar work without extraordinary measures Date Thu 1 Mar 2012 15 03 55 0600 From Tisha Hayes lt tisha hayes gmail com gt Subject R 390 URM 25 RF leakage and test gear originally picked up a URM 25 just to use the same piece of equipment as shown in the R 390A manuals found it to be a fine piece of mil grade gear for getting in the ballpark particularly when considering when it was made but not on par with modern test equipment plan on letting it go fairly soon When that happens as always the first option would go to folks on this list before ever went the eBay route for someone who just wanted to tear it apart to make a cool crystal radio When get in the mood will let y all know Date Thu 1 Mar 2012 13 24 04 0800 PST From Steve Toth lt stoth47 yahoo com gt Subject Re R 390 URM 25 RF leakage and test gear FWIW when aligned the HQ 129X I picked up used my URM25D with a frequency counter hooked in externally to the output Worked great After warm up the URM25D was rock solid and was able to bring in the required freqs spot on Date Thu 01 Mar 2012 16 43 06 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 URM 25 RF leakage and test gear I ve had the same results with mine also It simply is time to go through all the old caps and a few resistors to ensure the old gal stays up and running for a
403. lso advertises a reproduction of a ZM 11 U manual have been trying to find out without success which version of the ZM 11 these offerings describe before shell out hard money for either Any help Clues From Sam Doughty lt sdman cableone net gt Date Sat 29 Nov 2003 20 28 43 0600 Subject R 390 Deoxit Thanks everybody for the info on the Deoxit Another question What s a good signal generator for the 390 Looks like the URM 25 series is a good choice also the HP8640 might be a good one From Walter Wilson lt wewilson knology net gt Subject Re R 390 Signal Generators was Deoxit Date Sat 29 Nov 2003 10 00 05 0500 had the URM 25 for a while but it is harder to use and does not get down to the low signal levels you need to measure sensitivity on the R 390A Even with attenuators inline it leaks too much signal to be accurate for low levels now have the HP 8640B with options 1 and 3 This is a really nice signal generator includes a frequency counter is accurate at low levels etc etc If mine ever broke beyond repair I d have to quickly find and buy another one From Cecil Acuff lt chacuff cableone net gt test gear page 93 Subject Re R 390 Signal Generators was Deoxit Date Sat 29 Nov 2003 09 56 33 0600 Another excellent option and much more inexpensive than the 8640B is the old HP 606 A B They are built like a tank and seem to last forever Very easy to use and a true boat ancho
404. lt barry hausernet com gt Subject Re R 390 URM 25 Stability test gear page 317 Hi Nolan You wrote lt snipped gt read somewhere that copper screen strips a ete have some equipment with seals or whatever you call em like that Just picked up an R 2142 UGM 112 which is a glide slope localizer test receiver think This of course will help me in my work About the size of a URM 25 but much lighter similar case design in a way It has a groove in the backside of the front panel that goes all around with a metal mesh welting that crushes against the flange on the case when you screw it down A little like the grooves with rubber seals on the R 1051 panels but wire mesh have some mil computers with the same thing It s a silvery metal not copper as far as can tell maybe plated and it s a bit springy I m sure it must still be used on mil and certain industrial equipment so it should be possible to buy it by the foot Looks like a cross section would be about 1 8 X 1 4 rectangular or oval thereabouts Date Fri 15 Dec 2000 22 05 05 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 URM 25 Stability Yes the castings warm slowly which may slow thermally induced frequency changes And are fairy rigid minimizing thermally induced motion which can be hard on frequency stability Leakage is hard to improve Takes things like changing feed through capacitors to fee
405. lt chacuff cableone net gt Subject Re R 390 test equipment question Yup used the URM25 and it did do the job But is wasn t real easy because of it s accuracy Had to use a frequency counter to make sure it was on frequency test gear page 370 and wasn t drifting currently use the HP 410c love it and the 505 is a great analog meter My biggest gripe was the signal generator moved up to the 8640B because it had digital display but don t let that fool you It s a boatanchor too Probably was current issue in the early 70s if had to guess so it s nearly 30 years old It s not a synthesized modern marvel set the range switch dial up the needed frequency on the display and push the lock button which does a PLL type function to hold it exactly on the frequency desired if it drifts out of lock range the display flashes Release the lock reset the frequency and relock Works much easier and presents a 50 ohm load work on modern gear as well so it was needed for that too What you have is all one really needs to do the work on the R 390 series and don t think anybody is trying to sell you on something else But if you ever decide to upgrade you know what s out there to go to also have an HP 606A which like using as well It s a necessity on the 50KC IF s Date Sun 15 Feb 2009 21 05 45 0500 From frankshughes aim com Subject R 390 HP 8640b really wanted an HP 8640b but when Googled found so
406. lt grin gt Fair Radio used to have some real good deals on coax connectors You might want to drop them a note and see Surplus Sales of Nebraska had a really good price on NOS milspec type C connectors a while back think that they were three or four dollars each Oh while you have the URM 25D apart replace the male BNC connector that sticks out of the black aluminum box J103 with one with a hex head base flange Any time you remove the buffer amplifier subassembly you need to back that coax test gear page 284 connector out about 8 turns or so for clearance The one that s installed from the factory has no hex head and is a pain to mess with With the hex head a wrench makes it a snap gt Took a look with a decent web browser and see only Times EMR 200 that claims to be 100 coverage with two shields Is that an appropriate coax or is gt there another suggestion thought that 98 was the minimum guaranteed shielding for all milspec RG rated coax gt Also thought saw someone who said he d bought some surplus double shielded HP cables Ain t none of them there place like that in these here parts gt gt gt Equally good results are had with some surplus DEC Belden 50 Ohm gt gt gt double shielded extra flexible network RG 58 size cable It might be worth checking with one of your larger local computer shops One that does a lot of network work for businesses and schools etc Ease by
407. lt rgibboni Imdulye com gt Subject RE R 390 OT 30V regulator test gear page 160 How about using a 28 or 30 volt wall wart from a computer The 9 volt batteries are a good idea Roger WA3YTM Date Tue 18 Sep 2007 09 22 16 1200 From kenny lt igloo99nz yahoo co nz gt Subject Re R 390 OT 30V regulator have recently been searching for a voltage regulator for a 50 volt supply that want to build So far have had no luck at all and may have to consider using transistors to help with regulation although on the circuit that found one of the author s first comments was the regulation is not as good as with a IC regulator so I m probably back to the drawing board on that one Someone suggested the LM317 Yes would agree They are cheap and easy to obtain and you can adjust the voltage Even though the 30 volts is only used on the high ohms range would go ahead and build it if were you as it would bug me if had a piece of equipment that couldn t get full use of expect many of us are like that that s part of the reason we embark on restoring our BA s Regarding the 1 5 volt supply don t recall the type numbers because during my search 1 5 volts did not interest me but did notice many regulators that can be adjusted down to this voltage Regarding the supply that want to build My wishlist is for it to be fully regulated and stable 50V and adjustable over a small range 48 51V don t want to buy one
408. luck ended up getting WLS at 890 KHz but it was way down at the 540 KHz side of the tuning dial Sweeping the tuning dial up on the radio found that it was filled with Morse code some AM voice SSB in the 160 meter band and a few international shortwave broadcasters borrowed a few of my dad s alligator clips and attached the rather wimpy line cord wrapped FM antenna lead to my bedsprings left that radio in that state of mis tuning until was out of high school and on my way to college Date Sat 01 Aug 2009 13 26 22 0400 From 2002tii lt bmw2002tii nerdshack com gt test gear page 206 Subject Re R 390 OT Problem with HP 606A linearity gt Someone suggested that reorienting the dial That was me glad it helped You can probably get the saddle in the error curve out if you fiddle some more it all depends on how much time you re willing to spend on it Best regards Don Date Sat 1 Aug 2009 12 56 07 0500 From Barry lt n4buq knology net gt Subject Re R 390 OT Problem with HP 606A linearity Yes it was you and a fellow from another list who used to work at HP and seemed to know this was the right way to go Yes do plan to try to at least move the saddle point the plot looks kind of like a sine wave in an attempt to at least get the dial within spec If there are other things can do to reduce the errors I d be interested in knowing what they are I hope it doesn t involve rebending
409. lure mode intermittent modulation Starts up when you switch it on then quits Switch the mod off for a second then back on works again for a while Phil don t know if that F manual will be much help As recall Nolan Lee s explanation there are substantial differences even between some adjacent letters like the C and the D If my foggy memory serves best as it can think he said the F returned to the C style circuitry though the front panel doesn t look the same Whichever it is though a buck or two in caps fixes it Did you try switching the modulation on and off to see if there s anything there at all Date Wed 19 Dec 2001 19 27 54 EST From Llgpt aol com Subject Re R 390 URM 25D info The URM 25F has more attenuator steps that s the only difference test gear page 330 Date Wed 19 Dec 2001 19 12 41 0600 From blw lt ba williams charter net gt Subject Re R 390 URM 25D info It s good to hear from you again and on this list too have a nice URM 25D that bought from Fair Radio It was 90 as unchecked but was assured that it would be checked over without the checked price You can t beat the service as they sent me the upgrade caps xeroxed instructions all accessories and a replacement cover as the original case cover was heavily dented also got a little bag of spare bulbs and knobs The 400 Hz and 1 mHz mod are 4 caps that have to be replaced It sounds easy but getting in there to do th
410. ly will outlast the plastic several time The 465 was sold in very large quantities The 465B probably was an improvement The functional difference between the 465 and the HP 1740 a good scope too some thought easier to teach to new users is that when you check the trigger wave form on the 465 that s all you get to see while that can effectively be a third channel on the 1740 Seems to me that 900 series were Sony s anyway Compared to any HP scope BEFORE the HP 1740 any Tek scope was two generations better Compared to any maker s scope at any era Tek scopes are generations better HP caught up with the 1740 I m satisfied with my 475 and I ve not looked back or forward at other scopes since Date Sun 28 May 2000 12 40 54 1000 From Chris Gill lt micro iig com au gt Subject Re R 390 probes have to agree with you Jerry and others re the Tek scopes was the tech responsible for ICAR in IBM in the late 70 s apart from 549 564 storage types there were 100 453 s a few 454 s plus the modern 465 amp 475 and a few 485 s Without exception they easily surpassed their spec s early 50Mhz bandwidth 453 s with nuvistor front ends tended to roll off 8db down above test gear page 13 65mhz but later Fet front ends typically achieved the 90 100mhz and could still read up to about 150Mhz Good performance is achieved with the 465 475 series as Jerry points out the only criticism we had of the 475 is that the trace was
411. ly set up for 3 6 MC though the URM 25F states authoritatively that it is responding to 2 9 MC Sez so right on the dial it wouldn t lie not to mention the modulator works on this one I d like to make it do 455 KC but a canned coil would have to be changed out Anybody familiar with these Yeah know wrong list As long as I ve gone this far lt yawn gt will share with you guys that someone who will remain nameless suggested that the siggen of choice is the HP 8640 Why he even went so far as to say the URM 25x is crude and he wouldn t use it on an R 390 x Hmmmph The URM 25 is the official siggen of the R 390 the one in the line drawings in the how to section of the official manuals like Gatorade is to sports etc Also while I m at it there are other considerations with the proper wadding you probably could fire a URM 25 from a 16 inch gun Probably can t do that with the HP Here s a test requiring no special lowa class equipments close up one URM 25 of any particular letter denomination with all accessories in the lid and fasten with the spring loaded latches as per manual Secure HP 8640 of any particular letter model B etc as best you can put the line cord and any accessories in a suitable container as this siggen lacks the wherewithal to store its own stuff Test phase one Drop the URM 25x onto the HP 8640 from a height of 24 inches Test phase 2 Drop what remains of the HP 8640 onto test gear pag
412. ly the 590As have seen are not as good by 15 20 dB at gt some frequencies Date Thu 1 Mar 2012 18 54 19 0600 From lt wb5uom hughes net gt Subject Re R 390 receiver sensitivity testing Yes agree sort of If do the standard test and can follow the 1000hz tone all the way down with my ole going deaf hearing think should be able to do the same test in SSB mode with voice using my aforementioned service monitor I will let others say if its lab grade or not aeroflex 3920 Covers on screws tight and a 1 foot coax from generator to antenna input in my living room wih not much electrical on in the house Date Fri 2 Mar 2012 08 59 15 0800 From Francesco Ledda lt frledda att net gt Subject Re R 390 AN URM 25s worked on the Nike myself as a sys engineer for an European defense contractor Our systems were Block 3 with solid state receivers digital angle encoders replaced the potentiometers for az el and a norden pdp 11 dig ballistic computer replaced the 2 cabinets of the analog mech computer The reliability of the block 3 system was very good No need to balance those vacuum tube op amps It was fun Date Thu 1 Mar 2012 19 07 59 0600 CST From nryan mchsi com Subject Re R 390 AN URM 25s DUT device under test Date Thu 1 Mar 2012 21 37 53 0500 From Barry lt n4buq knology net gt Subject Re R 390 AN URM 25s gt they leak RF like a sieve 5 test g
413. m shadow lt shadow gilroy com gt Subject R 390 Dallas Lankford Mod notes URM 25D have scanned the Mod notes Walt W2OKF is going to convert them to a PDF file When completed The people that have requested them will receive them Date Sat 04 Jan 2003 19 05 46 0500 From Bob Camp lt ham cq nu gt Subject Re R 390 kilocycle megacycle movement test gear page 340 There is nothing particularly magic about the URM 25 generator Obviously it s the one in the TM s and that is a nice thing Other than that there are other generators both tube and solid state that will do the job very well Several of the HP tube type generators come available on a regular basis at a price below what you usually see URM 25 going for For that matter the radio will wind up working every bit as well set up properly with your Heathkit as it will with a URM 25 Now an analog VTVM is something that you can t easily replace From Kurt Schnabel lt classicmotorcycleclub hotmail com gt Date Fri 17 Jan 2003 16 55 40 0200 Subject R 390 URM 25 D Signal Generator am trying to repair two URM 25D Signal Generators but need the schematics Is there any Site which can download it Many thanks for any info Date Fri 17 Jan 2003 13 13 24 0600 From r390a enteract com Subject Re R 390 URM 25 D Signal Generator http bama sbc edu under Military Test Gear Date Fri 17 Jan 2003 15 05 14 0500 From Roy Morgan lt roy
414. m the extending wires to size IMHO the army method is far faster and safer suspect that one could make 10 of the Army design before one could make one the other way But this is America and one can pay ones money and can do what s a personal preference Date Mon 17 Sep 2007 14 17 34 0400 From Barry lt n4buq knology net gt Subject R 390 OT 30V regulator Not much on the list for a while so would like to ask an OT question have an old Triplett 630 NA meter and would like to use the ohmmeter section It takes a 30V battery which is still available and a 1 5V D cell for ohm functions was thinking of making a small 30V regulated powerr supply and house it inside the cabinet This is an older kind of rough condition meter that keep because my father gave it to me so modifying it doesn t bother me too much was thinking of a 24VAC xfmr with a full wave bridge a cap and possibly a 3 terminal regulator but didn t know if a 30V 3 terminal regulator is available Also would like to make a 1 5V power supply for the D cell but not sure if a 1 or 1 5 xfmr could be had as well as whether a 1 5V regulator is available Any thoughts Thanks Date Mon 17 Sep 2007 14 27 48 0400 From Steve Byan lt stevebyan mac com gt Subject Re R 390 OT 30V regulator test gear page 159 The LM317 will handle up to 40 volts on the input and can be configured to supply 30 volts If the unregulated input is above 30 volts then
415. me weaknesses that are a real pain to repair some variants are worse than others so some research is appropriate 465 s can t be reconfigured to improve or add new capabilities either Date Fri 27 Oct 2000 11 51 10 0600 From Chip Owens lt owens atd ucar edu gt Subject R 390 MX 1487 Adapter The R390A maintenance manual in section 6 2 8 specifies use of the Adapter Test MX 1487 URM 25D or Impedance Matching Network CV 206 URM 25F This is in conjunction with the adjustment of the Gain Adjust pot R519 Since don t have a URM 25 signal generator could someone please tell me what this adapter consists of and what people actually use in place of it Is it one of the little aluminum boxes that you use between the signal generator and the point in the circuit the signal gets injected Date Fri 27 Oct 2000 13 23 46 0500 From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 MX 1487 Adapter I m not sure if it s the same thing but Nolan Lee recently posted a link to the TB SIG 319 document which is a technical bulletin that shows the dummy loads that should be used to connect a URM 25 to an R390A They are different numbers than mentioned in the maintenance manual but think they are the same thing If they aren t would be interested in knowing the difference Are these dummy loads the same thing as what the maintenance manual calls an impedence matching network Along these lines does anyo
416. ment between the two to cancel out the temperature coefficient of the diode The chopper in the box switches between the two diodes more or less Sounds like yours is in working condition I d hang on to it They are not as forgiving of high voltage AC as some devices but they are great for low level signals From JM CO lt jmerritt2 capecod net gt Subject Re R 390 Manual copies HP 200CD and the older HP 200C Date Sat 31 Aug 2002 03 52 38 0400 HP manuals are serial number specific Please look at the first page for the numbers included and post them Newer manuals contain back dating information for older manuals but only up to a point Date Tue 10 Sep 2002 20 42 37 0700 From Walter Salmaniw lt salmaniw shaw ca gt Subject R 390 Re Capacitor Checkers test gear page 70 Fellas attended my local hamfest last weekend and picked up a couple of capacitor checkers to be used during my R390A rebuild I m almost embarrassed to say that paid 2 00 for one and 0 50 for the other The first is the Eico 950B while the other is unknown to me It s the Cornell Dubilier BF 90 Handicheck Does anyone have any experience with this one How useful is it in repairing boatanchors This one says that capacitors may be checked while in circuit but disconnect from the powerline before attempting to do this Comments By the way found on line a manual for the Eico but nothing about the BF 90 Date Tue 10 Sep 2002 22 42 23
417. ment with different capacitors for the SLOW AGC setting Probably not the big selling point here but it s a possibility have another alternative I m working that won t look quite so hokey but haven t scheduled time to go to the machine shop for it It too won t require any hacking to the deck and it will look a bit more like a real component Date Fri 20 Apr 2007 20 54 32 0500 From Don Reaves lt don reatek com gt Subject RE R 390 Capacitor checkers can offer you a pdf of the TO 4 manual about 1 6MB can email it direct to you or post it somewhere if your email would reject that size No attachments permitted here on the list Date Sun 3 Jun 2007 11 30 47 0700 PDT From W Li lt wli98122 yahoo com gt Subject R 390 re tube test extenders tip Here is a handy hint re tube extenders Some of them are faulty in that an internal wire has opened This is easy to spot if you confirm continuity between each pin its test point and its socket for EACH and EVERY pin prior to putting them into service We all know that they can be a convenient aid in checking operating tube pin voltages but what none of us need is a unrecognized faulty test tube extender ran into this problem as found out by rendering an operative R 390A inoperative by inserting a tube extender Took me a while to tumble to the fact that it was the extender and not me that was at fault Dumb me test gear page 146 One thing it pays t
418. mercury batteries You can solder two sets of three AAA cells and put them inside the meter case just fine The C cell it also uses is common and goes in the normal place for it The batteries are used on the ohms range the mercury cells ran a single FET for the ohms detector circuit The FET is NOT used on voltage measurements so hamfest hawkers who tout them as FET input meters are stretching the facts gt thought a TV 7 was a tube tester What are you doing that is so gt exact that you are worried about the voltage reading you are getting gt from you today s meters with there higher resistance per volt Adjusting the signal voltage in the TV 7 is the most critical setting think Date Sun 20 Mar 2005 14 13 14 EST From Llgpt aol com Subject Re R 390 OT Looking for TS 352 or AN URM 105 or 10000hm v tester Ah the Federal Government in their all consuming stupidity always does something like this The TS 352 series used 1 D cell and 3 4 5 volt batteries In their wisdom they surplused them out because the 4 5 volt batteries are no longer available That s the kind of thinking that has our country in financial trouble as type simply take a couple of plastic battery holders one for 3 AA batteries and one for a 9 volt battery Let s see 3 X 1 5 volts 4 5 volts 9 volts 4 5 volts 13 5 volts Gee why didn t they think of that have refitted more of the TS 352 series than you can shake a stick at over the year
419. mixer injection points Digital multimeters except for the rare Simpson with an auxiliary bar display are rotten for alignment First they are relatively slow to change then the user has to interpret the readings to detect the peak instead of merely moving the needle for a peak Real quick now is 2 73 volts more than 2 37 and 2 32 and 2 83 Though the front panel meters can be forced to work for nearly all alignment indications sometimes they are unhandy to see while keeping the alignment tool on the capacitor or slug needing peaking And they are fairly small compared to the scale of a VTVM A Heathkit or RCA or Eico VTVM is a worthwhile restoration project bad news if the ohmmeter battery has been left to rot inside and adequate for BA troubleshooting and alignment They are generally in low demand at hamfests and so don t bring much test gear page 45 Date Sat 20 May 2000 06 51 44 0500 From Tom Norris lt badger telalink net gt Subject Re R 390 Instruments gt A Heathkit or RCA or Eico VTVM Another recommendation is the Simpson 269 VOM it is 100K ohms per volt and has a meter face as large as a VoltOhmist with no AC cord to worry about tripping over They pop up every now and again We have them at work on every bench in the main lab been there since the lab opened in 1963 64 and except for a couple all are still in service and still to spec They are one of the few examples of instruments that HAVE
420. more mass to raise the temperature of in the 25D G H design than the 25F design gt That inside chamber has separate smaller chambers to isolate other parts of gt the circuit too And makes it a lot harder to work on gt So l m thinking that this unit has to be allowed to warm up for at least 2 hours before everything gets stable Did you let the beast run overnight and put the counter on it yet Date Fri 15 Dec 2000 10 46 20 0500 EST From Paul H Anderson lt pha pdq com gt Subject RE R 390 URM 25 Stability For my amusement and to test perceived stability of my URM 25D and HP 5328A counter ran the pair for nearly a week monitoring the drift wish I d been more careful recording the values but when set to the 1MC area it was drifting 2KC over a 24 hour period Now that know it is also sensitive to power line voltage should monitor that too Better yet can run some experiments with a semi fancy power conditioner I ve got and a Variac to see how far it allows voltage to drift then test gear page 315 use that in to power the URM 25D I ve enjoyed reading the URM 25 and other test equipment threads lots of good information there For the time being I m happy with the BA test gear but am aware could do better Date Fri 15 Dec 2000 11 11 59 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 URM 25 Stability The weight of the chamber
421. morgan nist gov gt Subject Re R 390 URM 25D info YES The resistors and capacitors in the Twin Tee oscillator circuit have drifted You need the Overhaul Notes written by Dallas Lankford and published by the folks who publish Hollow State news Do not tear your generator apart without reading Dallas s notes DO tear your generator apart and replace all repeat all of the now leaking paper foil capacitors in there You ll be glad you did gt downloaded the manual for the URM 25F test gear page 328 gt from the BAMA site but haven t looked at it yet How does the 25D compare gt circuit wise and mechanically to the 25F The circuit is very very close Mechanically they are quite different gt It appears that this would be a very good generator to align my longwave gt beacon receivers as it goes down to 10kHz YES this is right Date Wed 19 Dec 2001 18 08 29 0500 From Barry Hauser lt barry hausernet com gt Subject Re R 390 URM 25D info I m not the expert on these tho should study up as have a flock gaggle of URM s some of which need tending However looks like nobody has replied so far and can tell you this much Yes there are common failure modes concerning modulation with the URM 25x s When Fair Radio sells a checked unit they routinely replace 2 or 3 caps in that circuit When bought a reparable URM 25C a couple of years ago they threw in the caps with it but never got around to
422. n 31 May 2009 22 20 27 0500 From Barry lt n4buq knology net gt Subject R 390 HP 11042A Can someone please tell me what s inside of an HP 11042A Is it simply a capacitvely coupled tee device with two N connectors and a socket for the HP 410 RF probe can t seem to find much information on these on the net Date Sun 31 May 2009 23 53 37 0400 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 HP 11042A gt Can someone please tell me what s inside of an HP 11042A Information have a list of HP devices says HP 11042A probe T connector N for 410 series same as HP455A and the HP 410 manual indicates to me that it s simply a line section short coax line no capacitors from input to output with the port for the 410 probe can t put my hands on mine right now or the similar ones have made by some other company see below for an explanation for what those might be but seem to remember a capacitor coupling the center conductor to the RF probe tip found this in my notes file about the HP 410B gt did my homework last night and have got the information your requested gt Since several list members sent me comments about the overall 410 posting test gear page 199 gt thanks to all of you who replied there may be others desiring the same gt information So here goes gt gt The H P probe to which referred and which was used by the military as gt well as comm
423. n So had to take a look which was a 2 hour download of the BAMA TO 6a 8 meg file on 56k modem but it was worth it It looks like insulation resistance with the TO 6a is measured by matching instrument grid current to the capacitor leakage with some appropriate resistances to scale the resultant current measurment in the plate circuit of the instrument tube would guess nil here is still a pretty high resistance maybe in the 100 kohm range judging from the resistors in the circuit The manual indicates 100 Megohm to 100KMegohm ranges so maybe the lower limit is even above 1 megohm Maybe someone else knows the answer can t see the meter scale in the downloaded pic clearly enough to tell Thanks for the clarification only downside is I ll look twice at a TO 6a at some future swapmeet and be tempted Dan Date Thu 07 Apr 2005 10 43 42 0400 From Roy Morgan lt roy morgan nist gov gt Subject R 390 Ramblings on Calibration was HP 8640B Here are some ramblings about the topic of calibration On Accuracy of Measurements The expensive cal labs have three or four things we normally don t 1 Fancy specialized equipment to do the calibrations with 2 Reference standards traceable to NIST which costs them to keep current 3 Well worked out accepted and proven procedures 4 Trained experienced people to do the work For example in the measurement of frequency as done in the calibration of a signal generator the lab m
424. n extended period of time plan to keep her around for quite awhile Even though also have more modern equipment the digital HP 3336B love the old gal She has got a certain thing about her I m only making her a little bit better and overhauled It is sort of like keeping the HP 410B as primary with a TS 505D U also Even though have a good quality DVM on hand Then test gear page 381 also have a TEK 5440 that can read up to 25Mc and down to less than 1mv per graduation All things get brought to bear when necessary My primary reason for the HP 3336B was to use as the VFO tied to my BC 610 and or T 213 However it is very readily shifted in duties since have a WECO to BNC adapter AND a cable already built with the WECO connector on one end and a BNC on the other Flexibility is a great commodity Makes challenges easier to overcome Date Thu 01 Mar 2012 19 43 19 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 AN URM 25s I ve worked with the guys performing repairs on radar sets and the like all the the same time the massive search radar was just above us in Western PA It saw out into the Atlantic We certainly didn t have all this isolation that has been described Yet we were able to get the MTRs Missile Tracking Radars repaired and tested Sorry but these were antiques in the early 70s Some of the circuit boards had discrete components such as 2N110s on one of the little boards
425. n eye out for small calibrators at surplus dealers I d love to find some I ve got and use test gear that spans from WWII to the early 1990 s Most of the stuff is way past it s prime as far as a commercial establishment would be concerned This doesn t mean that it s accuracy potential sucks it s just that the normal cost of commercial maintenance and calibration typically exceeds the value of the gear A lot of the gear isn t really user friendly by today s standards and is slow to use like the Leeds and Northrup resistance bridge and the Fluke differential voltmeter Anyone that has used a null meter type differential voltmeter or a galvanometer type decade resistance bridge knows precisely what I m talking about A modern digital meter will give you a reading in a fraction of the time But can make accurate measurements down in the hundredths of a percent accuracy range with these don t know about you guys but have a lot more time than money lt grin gt I ll spend 15 or 20 seconds getting the reading rather than shovel out the big test gear page 39 bucks for an instant reading of the same or lesser accuracy I ve spent money for professional calibration of certain instruments of mine sure The Fluke AC DC differential voltmeter cost me about 60 bucks for calibration only paid thirty five dollars for the instrument itself The L amp N resistance bridge was still well within specs and needed no adjustments th
426. n for 25 years so far and still works fine Also haven t been able to find a manual yet though it s so intuitive to operate a manual isn t needed for general use Trust me if you see one of these at a reasonable price GRAB it BTW this one isn t for sale Date Thu 16 Mar 2000 11 32 23 0500 From km1h juno com Subject Re R 390 frequency counter Agree on the RS and clones with a different name tried one a few years ago to assist in repairing a TS 940 where needed 3 counters to track the shenanigans of the PLL synthesizer The readings had a mind of their own Finally borrowed another HP5245L and finished the job The Heathkit IM 2410 is a fairly decent unit and covers 10Hz to 225MHz An old favorite if you have bench space is the HP5245L which is a basic 50MHz counter The 5253B plug in will take you to 500MHz and others go to 12 4GHz The 500 Mhz combo is often at flea markets for 50 or less They seem to run forever have both the Heath and the HP and both do the job and have never given me grief 73 Carl KM1H Date Thu 16 Mar 2000 17 10 24 0600 From Tom Lutz lt telutz pclink com gt Subject Re R 390 frequency counter test gear page 35 You are correct mine is the Radio Shack 22 306 You are also correct in that the sample size is somewhat small But for what use it for it works great Usually leave it hooked up to my URM 25 as a read out and find it very stable and accurate against other standar
427. n t done much fixing in that spot lately IIRC the tuning rate is a bit fast in some instances but the lock on feature is really neat The small footprint is a big asset The overall freq range is great was worried about it s operation in the HF area but it seems OK Not great for doing the alignment of a multi band HF revr with lots of back amp forth freq work but probably easier at that than a URM 25 If you can think of any specific questions I ll play with it a bit amp see what we learn Date Sun 09 Jan 2011 17 08 46 0600 From n4buq lt n4buq knology net gt Subject Re R 390 HP 8640B vs HP 8654A 8655A 11710B Yes aligning a set like the R390A where one might have to switch between the converter and the straight output because the frequencies are the 10mgc point might be a pain and wondered about that As for other questions assume the counter must be also switched back and forth between the two outputs so there s double the work when going above below the 10mgc point as well do like the smaller footprint though as have a fairly small work area Date Sun 09 Jan 2011 20 02 45 0500 From Al Parker lt anchor ec rr com gt Subject Re R 390 HP 8640B vs HP 8654A 8655A 11710B test gear page 229 No IIRC you don t need to do any switching of the counter it s cabled in at the rear do have manuals for all 3 units I think so if you want any of that info I ll get a look Date Sun 09 J
428. n using a tube tester would imagine that lots of tubes are discarded prematurely have always regarded the circuit the tube is working in as the best tester for the tube Tube testers have their place ie in a lab to check batches of tubes are in Spec etc Our family had a TV set that was purchased in 1956 it was still working well with most of the original tubes in 1975 Tubes like vertical and horizontal output damper diodes and the cascode triode in the front end were replaced a few times as they work harder but about twenty tubes were original and had survived daily use for two decades But if one had tested them on a tube tester regularly They would mostly have tested BAD Regards to all Bernie VK2ABN Date Sat 23 Mar 2013 23 19 09 0400 EDT From L L bahr lt pulsarxp embarqmail com gt Subject R 390 B amp K Dynascan Model 177 VTVM picked up a really nice B amp K Model 177 Dynascan VTVM today at a local hamfest and would love to find a manual for it It looks like it is new Bye chance is there anyone on here with a manual for one they would sell or steer me to where might find a copy checked the B amp K site which has manuals on it but this instrument is too old to list think this VTVM will really be useful aligning my old boat anchors Il see one was sold on e bay awhile back and the manual is 15 pages in number From Don Cunningham lt donc martineer net gt Subject Re R 390 B amp K Dynascan Mod
429. n your TV 7 Allow me to speculate on the black stuff This was probably conductive grease At IBM we used some of that stuff on a rotating medium velocity ground contact The contacts were gold but due to the necessity of having a good ground in the system constant current we had lots of problems with running different greases and running it dry We contacted William Nye Co and they suggested the conductive grease which solved our problems It is jet black and it is full of carbon black believe in a synthetic base If memory serves me correctly it was about 60 one ounce tube It like the Moly based greases are messy to use The particle size of the conductive particles is so small it gets into your pores and is tough to get oult Hope this helps Date Thu 1 Feb 2001 22 51 18 0800 From keith lt khgrant ix netcom com gt Subject R 390 Tube testers I m a new owner of a R390A and have been in the process of getting working I ve recapped all but the RF module so far I ve found a number of bad caps so far it operates much better already Now that I ve gotten this far my thoughts are turning to tubes and tube testing get the impression that most of you have some type of tube tester at hand to check your babies What type of tester should consider getting Which ones are good or bad Should look for one of the military issue TV series or something else would rather not invest as much in a tester as my radio
430. nce and vice versa The first thing would do is what you did straighten the outward bent fins It sounds to me as if the variable cap is not adding capacitance fast enough as it enters mesh from the high end of the band so try increasing this either by i bending the outer plates inward starting at the end where they start to mesh or ii if you have rotation to spare change the mechanics to give slightly more mesh when the dial is at the top limit In either case you would then adjust the inductor and trimmer cap Remember to adjust the inductor for the low end and the trimmer cap for the high end Do you have a manual for the 606 don t but some other HP oscillator manuals give detailed instructions for linearizing the dials so I d check the 606 manual Best regards Don Date Tue 21 Jul 2009 21 13 36 0500 From Barry lt n4buq knology net gt Subject Re R 390 OT Problem with HP 606A linearity Yes have a copy of the manual but it doesn t discuss linearity Just set the endpoints and not much else As far as trying to move the plates of the tuning capacitor closer together I m almost afraid to try that as there s minimum clearance as it is might be able to squeeze 0 010 or so but not sure if that would be enough to matter Maybe I ll try it though Date Sat 1 Aug 2009 08 55 40 0500 test gear page 204 From Barry lt n4buq knology net gt Subject Re R 390 OT Problem with HP 606A linearity Just th
431. nd 545 for a long time But those aren t movable without a couple army troops or a couple mules can move the 475 and paid for it hauling it to customer s locations even when was only looking at 60 Hz power problems Yes it was overkill but considered it a really long term investment And it has been serving me for at least 23 years and isn t yet obsolete for my needs Though it would be a little slow for troubleshooting a 1 4 GHz computer but I ll do that by the computer s guts not a scope anyway The maintenance man for the labs felt the 1740 were more modular and so were easier to maintain though I ve found the 475 is fairly modular and fully accessible while working when troubleshooting is needed Date Wed 03 Jan 2001 22 24 21 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 R 390A Manuals and O Scope Tek 564 don t think want one The main frame bandwidth is only 10 MHz The storage scope was a pain the tube expensive and prone to failure ISU s labs that used 561 before they went to the HP1740 found them very sensitive to humidity If left all summer in unairconditioned labs and fired up without drying they would consistently blow high voltage power supplies If dried for a week in an airconditioned office they didn t blow the power supplies test gear page 24 The normal gain of the input probably isn t great enough for an EKG though there probably was a narrow band s
432. nd each trace gt would display 100 of the time there was no switching back and forth had to go look at the scope to see if it had two independent time bases It doesn t It has two independent sets of vertical plates but only one hosizontal set But expect what Nolan is remembering is that you can use the sweep magnification function to simultaneously look at part of the waveform shown on the upper trace magnified on the bottom trace test gear page 5 gt It s too bad that the bandwidth of the 500 and 502A were only gt a Mhz or so Come to think of it think that the 502A had more gt bandwidth than the 502 Maybe it was a 2 Mhz scope or it was the 1Mhz gt one and the 502 was a 500Khz scope need to dig around and find the manuals to be sure have the 502 and the 502 manual It s specs are 200 microvolts per centimeter deflection at 100 kc that s what the manual says not kHz and 0 2 volts cm at 1 mc These scopes are still of interest to audiophiles not for the tubes but probably for that as well but because they are very high sensitivity and have very good differential input rejection ratios seem to recall Stan Griffith telling me that it was this that made these scopes so unique but to maintain the ratios required great care in selecting replacment tubes for the vertical amplifier Of interest is that there are transistors in this scope kid you not A 2N301 and 2 2N214s Germanium think Even then sand was
433. nd is prone to an aging problem of nylon gear breakage Nevertheless the 8640B is reasonably easy to work on and with patience the broken gears are typically fixable know that there are other common vacuum tube generators that will fit the bill but I m not really up to speed on what s available Perhaps others on the list can help out there Date Fri 25 Jan 2008 19 02 05 EST From JRFKESRI aol com Subject R 390 no subject Harold if you can find an old URM 25 they are perfect for the job In fact that is what used in the Navy when repaired R390A s Sometimes they show up on ebay or try Fair radio http www fairradio com catalog php mode search amp query URM 25 Date Fri 25 Jan 2008 18 16 14 0600 From Bill amp Becky Marvin lt wmarvin hickorytech net gt Subject Re R 390 no subject test gear page 169 bought mine also from Ebay and was fortunate to buy URM25G model that is refurbished Date Fri 25 Jan 2008 19 38 24 0500 From Harold Hairston lt k4hca alltel net gt Subject R 390 Re Collins Re TEST EQUIPMENT RECOMMENDATION Dern forgot that have a good Frequency Counter That s it though Sry Date Fri 25 Jan 2008 22 36 32 EST From DJED1 aol com Subject Re R 390 TEST EQUIPMENT RECOMMENDATION It sounds like you have most of what you need The VTVM is critical for some measurements and the scope is useful for troubleshooting You will need a signal generator my Heathkit gene
434. ne know the impedence of the cable mentioned in that bulletin It is CG 409 U assume it would be 50 ohm from the signal generator to the dummy load but they use the same thing from the dummy load to the receiver where the impedence is about 150 ohms I think notice they are pretty specific about the lengths which is assume why they chose a particular cable Any comments Date Fri 27 Oct 2000 13 09 18 0500 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 MX 1487 Adapter Yes MX1487 URM 25D and CV 206 URM 25F are little boxes that are used between the generator and the radio In this case simply a 51 ohm feed through test gear page 19 termination E g two connectors connected together with a 51 ohm resistor to ground Quite easily simulated with a BNC T connector and a 51 ohm coaxial termination found this out by looking at my partial URM 25D manual which shows the adapters in the schematic and by opening up the accessories in the front of my URM 25F cover Date Fri 27 Oct 2000 13 22 30 0500 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 MX 1487 Adapter The GC s in my URM 25F cover look like RG 58 Two are 5 long the other one is several feet long but not tagged so probably isn t the original and it doesn t reach from connector clip to connector clip Next time stumble over that way I ll look at the cables to see if the
435. ne of the digits became intermittent Opening the case revealed that the Icd was a pressure fit to the contacts cleaned the contacts with an eraser then reformed I was taught long ago that you never bend anything the contacts to provide more pressure and the meter has worked well ever since BTW it reads within a few tenths of my Fluke 87 III As for the Taiwan machine tools consider them a work in process From krk ix netcom com Date Fri 09 May 2003 18 10 10 0700 Subject R 390 Re OT CHEAP DVM S Actually H F has two different meters One which is part no 30756 is the one they have on sale at 2 99 while the other one is part no 35761 which is on sale at 3 99 The difference is the 35761 has a couple of greenish LED backlights for the display which can be turned on off with a slide switch located in the upper left of the panel have both of them in front of me just tried them on a 1k ohm 005 lab precision resistor and the 30756 said 1002 while the 35761 said 998 They say it does 0 8 of range 2 digits Looks like they are close enough for 3 or 4 If you can get the 35761 for 2 99 you scored a buck Either way they come with the 9 volt battery BTW the panel lights work well Just like a 45 keep one in every room plus one in the truck lt grin gt Durn those Chinese lt nuther grin gt From Darryl Jones lt sherri darryl erols com gt Subject Re R 390 Re OT CHEAP DVM S Date Fri 9 M
436. need it It sure is a handsome thing and weighs about as much as an R390A so it has a built in cool factor but not sure if I d know how to fix it if it didn t work correctly It hasn t been powered up by the current owner but he said the fellow he bought it from said it worked Date Thu 15 Mar 2007 15 14 17 0400 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 General Radio Sweep Generator 1025A sent Barry some impressions that are summarized It s a GREAT instrument not easy to use but very capable and of course it IS a General Radio thing which makes me love it no matter what know of only a very few folks who have them Date Thu 15 Mar 2007 18 16 11 0400 From Mark Huss lt mhuss1 bellatlantic net gt Subject Re R 390 General Radio Sweep Generator 1025A test gear page 143 Not acquainted with it The only thing on an R 390 that will benefit from a sweep generator is the R 390 NOT R 390A IF Deck If it will sweep 445 to 465 kc it will turn a two to three hour job into a ten minute one Date 29 Mar 2007 14 04 38 0000 From n4bug knology net lt n4buq knology net gt Subject R 390 probably shouldn t admit this but About a year or so ago noticed the probe for my HP410B stopped heating and was getting no AC readings After checking discovered the probe has an EA53 a 6 3VAC filament diode instead of a 2 01C a 5VAC filament diode and the heater voltage had been set to 5VAC
437. net gt Date Fri 4 Jan 1980 09 17 32 0600 Subject R 390 Plastic Gears Help my 8640B just busted a gear in the Range selector assembly Would anybody know where could find one or does anyone of you have a spare or a junker for sale Was in the middle of an alignment and can t go any father Subject RE R 390 Plastic Gears Date Mon 2 Feb 2004 13 53 07 0800 From David Wise lt David_Wise Phoenix com gt repaired one of the bevel gears in mine The plastic they used shrinks over time and eventually gets so tight on the metal core that it bursts ground out the hole until when the break was squeezed shut it was a sliding fit on the core Then roughened the core and glued them together with JB Weld A plastic wire tie held the break shut while the epoxy hardened Not satisfied with this also reinforced the gear with a washer JB Welded to its flat backside As with the main bond roughened the surfaces Being a bevel gear the slight decrease in diameter was inconsequential It s been trouble free for a couple of years now This technique may also work on the spur gears One other thing found the detents to be ridiculously stiff on the Range and Deviation switches and took out a couple of leaf springs from each They re much lighter now without being sloppy which is very important for my unit as it doesn t have the original Range and Deviation knobs No doubt the originals got their flanges broken off from th
438. ney and ya takes ur choice Personally like the TV 2 have here also have a Triplett 3444 which like a lot Date Sun 20 Mar 2005 09 27 22 0800 From S Majerick lt stevem ci steilacoom wa us gt Subject R 390 RE B amp K 1602 Power Supply question Here s where you can order a manual for it http www bkmanuals com 1601 2000 htm Date Sun 20 Mar 2005 13 31 57 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 Looking for TS 352 or AN URM 105 or 1000ohm tester gt think the TS 352 is a battery powered meter If was surplused out gt as it used some non standard shaped batteries If you find a meter gt you likely cannot find batteries If I remember correctly the TS 323 is a very heavy indestructible VOM with cover and handle fine for boatanchor work but you have to move the probe lead to change ranges on it Not all that convenient Neat meter however The batteries were two three cell batteries with screw terminals on top you can simply solder together three AA batteries and put them into the battery compartment The batteries are only used on the OHMS scale There may also have been a D cell for the lowest range test gear page 115 If anyone has one of these and needs a manual think have a copy here also have a manual for the TS 505 VTVM mentioned in the R 390 repair and alignment procedures The TS 223 is another animal a much more modern plastic cased unit that used
439. ng up in the Northwest places like Fair Radio o0n Craigslist and last preference Epay Date Fri 13 Feb 2009 06 40 37 0500 From Roger Gibboni lt rgibboni dulye com gt Subject Re R 390 test equipment question The only thing would add to the list is a 1OOMHz scope A Tektronix 465 is a great scope that you can get for a few hundred dollars This will be invaluable in troubleshooting and will do the job of the RF VTVM as well Roger WA3YTM Date Fri 13 Feb 2009 08 58 47 0500 From Miles B Anderson K2CBY lt k2cby optonline net gt Subject R 390 Test Equipment Question test gear page 175 If you re cutting down to the essentials really don t think you need anything more than you ve got If you need an audio generator you can take 400 Hz and 1kHz from the URM 25 An RF probe for the VTVM is helpful but you ve got to be careful that the input Capacitance is small enough so that you don t overload the citcuit and kill off the signal you are trying to measure have several scopes in the shop but frankly I ve never needed to use one to service an R 390A though it would be handy to check whether the crystal oscillators are running I ve also used a scope with a vertical amplifier output to act as a preamplifier for my frequency counter Perhaps the best oscillator check in the absence of a scope is to listen on the oscillator frequency or multiple with another receiver You can also use the VTVM to check the DC
440. nice it isn t mine http tinyurl com 2wbknr Date Thu 24 Jan 2008 21 49 01 0500 From Bob Camp lt ham cq nu gt Subject Re R 390 FA GR Audio Meter Cute little thing Certainly worth the money if it s even close to working Date Fri 25 Jan 2008 00 26 44 0500 From roy morgan nist gov Subject Re R 390 FA GR Audio Meter Would be audio power output measurers The GR 1840A output power meter is the fourth and last of such things GR made It is in fact superb Once you have one you wonder how you got along without it till then It measures from 0 1 milliwatts up to 20 watts directly and can be set for any practical impedance load 0 6 ohms to 32 kilohms It is for all practical purposes flat and plenty accurate for any uses we would have Cute trick get a separate load resistor put the output power meter in parallel with that and set the meter for 10 times the load resistor The thing will then indicate one tenth the power in the load This gets you to 200 watts easily Or you can make a T network as the manual explains Note the one for auction has a bid of 15 just now but normally they go on ebay for up to 100 or a bit more though lately one or two have sold for more modest prices 300193100784 There is a manual scan available at http www jptronics org radios for anyone who might buy it or already have one Date Fri 25 Jan 2008 18 13 53 0500 From Harold Hairston lt k4hca alltel net gt Subject
441. nnected to the adapter didn t think of unscrewing the probe tip but can see how that would work had seen the xreference to the 455A as well but haven t seen any of those available either I ll have to keep watching the bay Date Mon 8 Jun 2009 13 05 54 0500 From Barry lt n4buq knology net gt Subject R 390 OT just a bit From whence cometh the grid current have an HP 606A that I m checking over and have found the voltage on the screen grid of one of the 6AW8A amplifiers in the power supply is off low a bit The voltage is supplied to the screen grid via a voltage divider from B that consists of a 1 2M and a 100K resistor from B 500V to ground With a 500V supply and nothing else connected this theoritically gives 38V at the junction of these two resistors If unplug the tube and measure the voltage at the screen grid pin get close to 38V however when plug in the tube it drops to about 32V My question is where is the grid current coming from Is it coming from ground up through the 100K or from B down through the 1 2M assume it draws it from ground because as little as 1mA would drop a significant amount of voltage through that 1 2M resistor Sorry if this is a really dumb question but just don t seem to understand how the current flows in this simple little circuit assume that since I m measuring the voltage from ground to the screen and plugging in the tube drops the voltage then the cu
442. nob helped some and fitting a larger knob with a crank handle helped even more let it go at that having no frame of reference for how smoothly one of these signal generators should tune The parts rig got test gear page 306 me to investigating the working unit found the cover over the frequency adjust section had no rubber gasket the Dayton one did removed the two knobs on the bench unit and loosened the cover Immediately the tuning shaft freed up After a lot of fiddling found the cover needed to have the four holes on the cover enlarged a bit to enable the screws to go through the cover and into the studs underneath without causing the tuning shaft to bind While in there took off the black masking disk clear plastic piece with the line scribed and the frequency dial under it Cleaned everything put a drop of oil on the bronze bushings and put everything back together being careful to preload the two piece split dial gear Shaft resumed binding Drat Took the cover off again and after a while determined that the cover needs that missing gasket to elevate the cover a millimeter or so Even one of the dial lamps those teensty 323 s was pressing on the clear plastic bit and contributed to binding It s a wonder didn t break the little bulb In the end added spacer washers to the four studs under the cover to elevate it and made a promise to locate some replacement gasketing It s the U shaped profile stuff that I m at a l
443. nslating stage and pass stage are inverting common emitter or non inverting common base emitter follower have successfully built regulators for over 1000 volts and up to 1000 mA this way Op amp application notes are full of circuits like these Date Tue 18 Sep 2007 00 09 24 0400 From Mark Huss lt mhuss1 bellatlantic net gt Subject Re R 390 OT 30V regulator Linear makes the LT3012 3013 3014 that provides up to 60 volts regulated at from 20 to 250 mA remember we used a linear high voltage regulator that could take up to 105 volts in and provide up to 95 volts out If memory serves it was made by National Semi Can t for the life of me remember the part number and a look at the site does not reveal it Could not provide much current And it used a MOSFET pass transistor so the voltage drop was humungous TubeCad Journal has a selection of high voltage power supplies greater than 30 volts using tubes semiconductors or a combination of both Date Mon 17 Sep 2007 21 53 38 0700 From John Kolb lt jlkolb jlkolb cts com gt Subject Re R 390 OT 30V regulator Having to plug in the meter whenever took it somewhere besides my bench would be a real drag You might consider putting a plastic baggie around the battery with just two small holes for the battery holder contacts to prevent damage from leaks Got my 30V battery at Radio Shack Date Tue 18 Sep 2007 23 51 13 1200 From kenny lt igloo99nz yahoo c
444. nt gt lt venting gt Big Evil Grin All the above being said can t think of a better signal source than the URM 25 Like the Energizer Bunny TM it just keeps on going and going The frequency range covers EVERYTHING in LF MF HF communications which am liable to run into in the natural course of things If one carries out proper maintenance and uses deoxit etc etc one doesn t have any problems From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 Suggested Test Equipment for R 390A Alignment Date Tue 8 Apr 2003 20 41 47 0500 used a URM 25 for a while until picked up a nice HP 606A gave away the 25 Probably the same vintage as the R 390A larger than the URM 25 but think easier to use personal opinion also have a HP 8640B and love it but it don t go down to 500Khz unless you use the audio out as the generator at that freq From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 Suggested Test Equipment for R 390A Alignment Date Tue 8 Apr 2003 22 08 49 0500 Mike is right the 8640B does go down below 500Khz was confused I picked up the 606A because of several radio s have that use 50Khz IF s not 500Khz as stated have a couple Halli s and HQ series Hammarlunds All that said the HP 606 is a good alternative for the URM 25 if one wants something closer to Lab Grade for someone working on an R 390X series or any of the above mentioned Cost is about the s
445. nt them from doing something stupid just saying read your manual should have made it clear that the external reference is 5 MHz for the 8640B but did not really plan on delving into the optional nicessities of my set up in that post The external refenence is really not needed since the 8640B is very accurate on it s own test gear page 235 use an external reference s to make the many pieces of my equipment closely agree with each other As they say A man with a clock always knows the time A man with two clocks is never quite sure Date Tue 11 Jan 2011 22 50 04 0700 GMT 07 00 From Richard W Solomon lt w1ksz earthlink net gt Subject Re R 390 8640B Gee my 8640B goes a LOT lower than 450 MHZ Date Wed 12 Jan 2011 03 40 28 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 8640B It s a function of the individual cavity assembly They are specified to 500 kHz most will get to about 445 Date Wed 12 Jan 2011 04 28 34 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 8640B Contrarian opinion The 8656 57 synthesized oscillators don t equal the 8640B where close in spectral purity and low phase noise are concerned Note that they are not specified for spurious output within 5 kHz of the carrier and for good reason Their output attenuators are prone to problems also and signal leakage from the enclosure is much worse than an 8640B enough that
446. num ber2 amp partnumber3 amp pq Search for distributors with stock and http www keyelco com kec standpro sprod15 htm and http concord elex com cgi bin partO cgi pg SL 0 amp pi 319 These pages show pictures and part numbers but refrained from overloading the qth net server and those without browsers from sending them to any but Nolan last night Mon 07 Feb 2000 13 34 27 0600 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 URM 25D Refurbishment The simple wide band oscillator in the 25D should have a great deal more phase noise than the R 390 There was an article or letter to the editor in a Proceedings of the IRE long about 1963 a couple years Proceedings of the IEEE after 63 that suggested an odd multiple of a quarter wave of coax and a double balance mixer could be used to extract phase noise from an oscillator The coax makes a phase shifter the longer the better and when the frequency or line length is adjust to make the phase shift exactly 90 or 90 degrees the double balanced modulator acts as a phase detector then the phase noise can be read out with an audio spectrum analyzer Far simpler than using a pair of oscillators to cancel out the carrier and probably double the phase noise Far cheaper than finding a spectrum analyzer with noise lower than the oscillator I ve not yet tried the coax scheme and don t remember the calibration but it can be calibrated Date Thu 17 Fe
447. o Best regards Don Date Sat 14 Feb 2009 05 51 33 0800 PST From Michael OBrien lt mikobrien yahoo com gt Subject Re R 390 test equipment question have 2 of the 8640B s and like them How can you tell if the gears are cracked or broken One of mine had been rebuilt that bought from a guy on ebay that does that kind of work Date Sat 14 Feb 2009 08 54 20 0500 From Kim Herron lt kim herron sbcglobal net gt Subject Re R 390 test equipment question Peel the covers off and look If the gears are cracked you ll see it Date Sat 14 Feb 2009 08 06 55 0800 PST From Steve Toth lt stoth47 yahoo com gt Subject R 390 test equipment question Thanks for the inputs on test equipment now have a schematic for a simple RF probe to use with the VTVM good input on choices for my next signal generator and good suggestions for an inexpensive O scope the info actually helped me avoid what could have been a potentially bad purchase of an O scope locally Received some good troublshooting tips too Date Sat 14 Feb 2009 14 49 58 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 test equipment question The gear hubs sometimes crack and you can tell by inspection as has already been mentioned Also look at the one large nylon gear it can shrink enough that it loses proper tooth engagement and can skip even if it is not cracked this is the most common gear fault have observed
448. o hated to waste the other type J but really didn t have much choice I ve been keeping my eyes open for a spare 2 5K type J pot with the shaft lock but as of yet it appears that they re non existent As much trouble as it is to remove that pot if do I m going to put a new one in it s place The one in the F model is a snap to get to though wouldn t hesitate to experiment with it gt Also treated the set microvolts to 10 rheostat 000 That ones another one that s commonly bad The ones that are currently in both my D and F models are good and lucked into a NOS spare last year They re hard as hell to find and when you do pretty evil to change gt Bottom line on the two pots cceeeeeees I m glad it worked out for you OK The way that my luck runs I d have done what you did and have had to end up pulling them out again and replacing them lt grin gt gt Stabilant isn t cheap secccoes scenes seseeed cosus ta eanecteese Their prices are a lot higher than I m willing to pay especially after the way they treated me on the phone called them for an MSD sheet a couple of years back nolan test gear page 304 Date Sat 05 Feb 2000 19 16 45 0600 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 URM 25D pots Actually http www hhsmith com shaftaccess html for a picture http www netcomponents com cgibin hhsmith asp partnumber1 181 amp part
449. o the nearest 1 Hz and know it will stay there And of course its got a nice HP attenuator to set the signal level down to 01 microvolts It makes it easy to check test gear page 364 the PTO just dial up the frequency in 25 000 KHz steps and see what the dial reads There are a couple of drawbacks it s heavy so it costs a lot to ship and it s a lot more complicated to maintain if something breaks But if you want to be authentic to the 50s era then the URM 25 is the way to go Date Sun 10 Jun 2007 13 47 20 0700 From Kenneth G Gordon lt kgordon2006 verizon net gt Subject RE R 390 WTD AN URM 25 The AN URM 25 is a pretty good OLD unit but there are better more useable signal generators which do a far better job don t like their drift at the higher frequencies and you must use a frequency counter with them in order to really know where you are If you really want an AN URM 25 get hold of Ashley in Oregon who completely rebuilds them for IMHO peanuts She does a superb job and often times has rebuilt units for sale on the bay Do a search for URM 25 to see what pops up Personally would prefer to use practically any of the more modern units which cover the required frequency ranges The HP 8640B WAS an excellent choice but since those used nylon gears many of those units are becoming unusuable since the gears are gradually going away and there are no replacements have an HP 8640B which use a lo
450. o back diodes in parallel so long as its has no internal multiplier The diodes can be substantial at least and amp or two rating and need to be silicon The typical 1 ma meter movement has about 50 millivolts drop and at that voltage the forward current of the silicon diode is pico amps essentially an open circuit While germanium diodes conduct at a lower forward voltage their leakage is significant at all voltages so they can upset the meter calibration Silicon power Schottky may give more protection than ordinary silicon For some reason at Collins in 1964 that was NOT standard practice and with the high voltage multipliers located outside in the power supply cage we lost a few meters until added that meter protection Once added the diodes and proved to the old timers that the diodes didn t change the calibration foggy days didn t wipe out plate voltage meters they just read very high Any fuses need to be rated for interruption voltage fear the pico fuses may not be rated for high voltage interruption Read their specification Ordinary fast blow fuses may be cheaper or may not be The very low current fuses classically used a platinum hair for the fuse element and were several bucks each The same fuses were used for microwave bolometers where the RF power applied changed the resistance and the test equipment measured that change often by putting reducing the DC bias voltage to keep the same resistance so the RF power was equal
451. o deOxit all the pins when you get them They are often crudded up One principle that have learned through the years is to continuously go thru and double check my test equipment It is a bit like preflight checks 99 boredom and 1 panic at discovering a fault As an example use a T BNC connector on my URM 25F and monitor its frequency with a modern counter This advice may seem elementary but sadly it is the simple obvious stuff that often gets us W Li Date Mon 25 Jun 2007 14 18 09 0400 From Roger Gibboni lt rgibboni Imdulye com gt Subject R 390 Tube testers Does anyone have an opinion on a TV 7 versus a TV 2 tube tester need one Date Mon 25 Jun 2007 14 20 56 0400 From Tracy Fort lt beerbarrel cox net gt Subject RE R 390 Tube testers had both The TV 7 is quicker for sure but liked the TV 2 because it is much easier to work on and is not to hard to set up when you get used to it Date Mon 25 Jun 2007 14 38 11 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 Tube esters like my TV 10D but you will have a tough time finding one they are rare Date Mon 25 Jun 2007 18 14 40 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 Tube testers Both will tell you approximately how good the tube is Neither one is going to be 100 for telling you if the tube will work in a R 390 or not would get which ever one looks to be in better shape Date
452. o know that your signal generator is giving you one half microvolt to three decimal places you probably have a ways to go In the meantime do have fun and tell the rest of us about what you are up to Date Thu 7 Apr 2005 15 29 46 EDT From DJED1 aol com Subject Re R 390 Ramblings on Calibration was HP 8640B Boy you guys put me to shame was going along setting the R 390A to WWV and thought 100 HZ was close enough Then got the 8660 signal generator and figured out how to measure the beat note so could read frequency to 1 or 2 Hz Now you tell me that 0 1 Hz is only OK accuracy And frequency was the one thing was doing good on accurate to 1 part in 107 On my voltmeters was going by the consensus method if two of them read the same then it must be correct The trouble was that the two that agreed were a precision power supply that got from a garage sale for 5 and a Radio Shack digital VOM from a similar source finally borrowed a calibrated Fluke 0 025 accuracy on DC from my son s shop and verified the the power supply and VOM were indeed correct to 0 1 Also verified that my H P 400E was still good to 1 on AC volts Fortunately calibrated my scope to the power supply so it s good test gear page 123 And used the scope to set up the URM 25 so it s good Now if could only get some precision caps and resistors to calibrate the rest of the VOM I d be all set Ed Date Fri 08 Apr 2005 09 16 52
453. o nz gt Subject R 390 OT 50 Volt Regulator Thanks guys for all your ideas and input the idea of floating the regulator had never occured to me that s a great idea will be studying the application notes on the LM723 and LM317 and build up a prototype and see how it goes The power supply want to build is rather elaborate it s for a linear amplifier project test gear page 164 that want to pursue It s actually three supplies in one enclosure need 50volts 50amps peak adjustable 38 to 50volts to set the bias and 12volts for the control circuitry No point even thinking of starting the amp project until the power supply is sorted and if make it adjustable over the full approx 40volt range of the regulator the supply can be used for other things as well Date Tue 18 Sep 2007 08 37 51 0400 From Tim Shoppa lt tshoppa wmata com gt Subject Re R 390 150 V regulator Any transient increase in load above the dropout current even say a module with some capacitance in it being plugged in would cause the regulator to go into foldback resulting in more than 40V across the terminals resulting in all the magic smoke coming out With the regulator on the audio deck but all the loads scattered about the other decks this is pushing it If BIG IF you wanted to solid state the OA2 the right choice truly is a solid state shunt regulator There s no shortage of 0A2 s especially mil spec OA2 s It s a very nice regulator t
454. obal net gt Subject Re R 390 URM 25 replacement Bob s post reminded of something saw in my URM 25s The URM 25 generator uses a switched series of resistors in its output attenuator the last being a 50 ohm ish to ground It s not 50 ohm but either 49 9 or 50 1 or something like that can t remember which In both of the URM 25s have owned that 50 ohm resistor was open Unless you actually measured the output of the generator you probably wouldn t notice the problem Then a couple of years ago Fair was selling the attenuator assembly as a separate part and bought one Guess what That resistor in that was open as well Another thing to check on your URM 25s Date Sat 26 Feb 2005 16 44 03 0500 From Bob Camp lt ham cq nu gt Subject Re R 390 URM 25 replacement According to the manual on Bama the magic resistor is 59 ohms It is DC coupled to the output jack If you hit the output jack with 12 volts then E 2 R gets you up test gear page 353 above 2 watts Most 1 4 watt metal film resistors aren t going to take that for a real long time The interesting thing is that it s always the final resistor that blows The 65 6 ohm parts in the rest of the attenuator aren t all that less likely to blow out With R 390 type stuff would suspect the whole attenuator goes if you have B on the antenna connector Not to mention a bit of a surprise to who ever is working on the radio Sounds like a great way to rig the
455. obe that became detached The wife went on a tear and moved things ALL over There are similar ser no issues with the manuals for the 410C Date Mon 18 May 2009 11 16 41 0400 From Jon Schlegel lt ews265 rochester rr com gt Subject Re R 390 HP410B Intermittent s The recent thread on the AC probe for the HP410C prompted me to look at a nagging problem on my 410B On Rx1 scale with leads open circuited and meter indicating full scale an intermittent existed somewhere as the full scale adjustment was not stable To make a long story short the problem looked like a solderability problem AT THE TIME OF MANUFACTURE The problem area was the smaller of the two resistor boards located on the left side of the instrument same side as the function switch The specific problem seems to be poor solderability of the foil on the circuit board They used rivets in the through holes of the board to keep the foil anchored and the solderability problem of the foil looked like it prevented a good joint between the two from the get go Removing the old gucky solder then liquid flux and heat seemed to give an OK joint It was surprising to see that kind of problem inside of an HP instrument It may be worthwhile to check for problems like this on anything that has intermittent problems that uses this construction technique As an aside it looks like the schematic symbol for CR1 metallic rectifier is reversed unless they were using some other cu
456. od peak reading wattmeter will should read 506 Watts 3 However an average reading actually RMS a misnomer wattmeter like a Bird 43 or thermal heating value wattmeter should read half the power i e 253 Watts just verified this with a pSpice simulation Lazy man s way of calculating the result The math is too tedious given the cyclic change of phase test gear page 222 relation between baseband exciting sources and you have to sort out an appropriate integration period Date Tue 20 Apr 2010 09 38 05 0400 From Barry lt n4buq knology net gt Subject R 390 HP 8601A Anyone have experience with an HP 8601A particularly for aligning R390s etc It seems like a decent generator as it covers the entire spectrum needed for these radios and think it is fairly leakproof Just wondering if there are any particularly bad things about them that would make them not a good choice for this application Date Tue 20 Apr 2010 15 11 19 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP 8601A It s a useful piece of equipment but IMO clearly in the don t pay real money for it class I ve seen a few go for 200 or more at auction which think is way too high you can get an OK 8640B for that money if you look If you find an 8601A that works for 50 75 however that s another story My experience is based on buying three working units with relatively minor problems for 40 and fixing them up fo
457. of Windex into the area to lubricate the thing If it s stuck push down at many places on the ring from straight above with a screwdriver to loosen it There is a rubber gasket to allow a tiny bit of play Once it starts it will go more easily If that fails take the thing to the home store and search for some copper pipe the right size to make a wrench Pipe a bit bigger can be bent in to fit Ensure equal pressure from each of the four fingers by careful filing Date Fri 8 Mar 2002 16 49 26 0800 PST From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 Re TS 505C U Manual This manual is on the R 390Y2K manual disk at least sent it to Jeff and some one else too Its out there somewhere If not have a copy of the manual think remember sending it to Ken Grimm of BAMA fame Date Fri 08 Mar 2002 18 09 20 0700 From Jordan lt jordana nucleus com gt Subject Re R 390 Re TS 505C U Manual The Link is http www logsa army mil etms find_etm cfm Type in TS 505 in the bottom dialogue box 73 de Jordan P S Please be prepared to wait awhile as I m sure the site will be flooded with requests as this gets out test gear page 64 Date Sat 09 Mar 2002 22 46 50 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 Re TS 505C U Manual gt gt http www logsa army mil etms find_etm cfm You will get three hits one is the spares parts list one is for the 505 model
458. of her work and it is really superb Furthermore she is a delight to talk with have no idea how old she is but she is someone whose services some of us may want to use sometime I ll try to dig out her e mail address mailing address and telephone number and will post them here later this evening after get home from work Date Sat 09 Jun 2007 16 18 20 0400 From rbethman lt rbethman comcast net gt Subject R 390 WTD AN URM 25 Subject says it Want to get one at a reasonable price Fair Radio has hit 200 Date Sat 9 Jun 2007 17 02 25 0400 From Al2Q lt ai2q adelphia net gt Subject Re R 390 WTD AN URM 25 Got mine at a hamfest for 25 Date Sat 9 Jun 2007 22 01 26 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 WTD AN URM 25 There is nothing magic about a URM 25 It s just what the military stocked for the job Any of the HP lab generators that cover the frequency range will do an equally good job on an R 390 have seen them show up cheap from time to time test gear page 363 Date Sun 10 Jun 2007 06 33 40 0400 From David C Hallam lt dhallam rapidsys com gt Subject RE R 390 WTD AN URM 25 know what you mean have a very nice HP 606B that picked up at a hamfest for 35 The only thing can find wrong with it is the frequency calibration is off Since connect my frequency counter to the uncalibrated output anyway have not bothered to fix that Maybe one of thes
459. of it think that the 502A had more bandwidth than the 502 Maybe it was a 2 Mhz scope or it was the 1Mhz one and the 502 was a 500Khz scope need to dig around and find the manuals to be sure The 502 and 502A were common as dirt around the New Orleans area about 15 years ago NASA Michoud and Stennis Space Center cut a bunch of them loose on the surplus market along with a mess of the higher numbered models and thousands of plug ins almost everything that was sold off was current as far as Calibration certification You don t see that much anymore gt Philips used to make some dual beam scopes back when was in technical school circa 1970 Nice scopes which put everybody to shame except Tek and HP in that order Those old Tektronix 500 series scopes were true works of art Wonderful examples of quality craftsmanship Date Mon 19 Jul 1999 14 51 46 0700 From dma islandnet com Subject Re R 390 Tek scope 502A gt It s been a few years since I ve owned any of them but seem to gt remember that Tektronix actually used the wording Dual Beam on the gt front panel and in the manuals to differentiate between them and the gt less expensive Dual Trace scopes Sure did I m looking at the manual and scope as hunt and peck gt The CRT used separate guns and deflection plates for each of the gt two channels for a really nice non flicker display You could set one gt beem to sweep at say a second and the other at a ms a
460. oken at any given point in time recall the outputs of the function generators and pulse generators were always blown The scopes of that era were hot pluggable but if you did that with the TM500 modules you would likely blow the plugin Date Sat 27 May 2000 11 20 45 0500 From Dr Gerald N Johnson lt geraldj ames net gt Subject Re R 390 probes test gear page 12 didn t consider the 5000 and 7000 series scopes when last shopped because needed portability Can t bring a power plant home to the shop nor a room sized printing plant motor controller or type setting system liked the 465 that I ve used found them to have enough screen intensity to see 100 ns pulses triggered by hand with full room lights was a little disappointed that the 475 doesn t quite have that sensitivity In the time period I ve owned the 475 its not been absolutely perfect though some of the failures have been mine one major one Tek s broke front end attenuators playing with arcing high voltage Have spares because ordered more than needed to fix it A rectifier in the power supply failed open and the worst thing was that the plastic cam for the delayed sweep switch coupling failed Though there was a Tek part number for it Tek would only sell the entire horizontal sweep board for half the going price of a used 475 carved a new cam out of aluminum with a little lathe work and a dremel cutter in the milling machine and it works perfect
461. oking into buying a signal generator to align my R 390A Is there a difference between the militarized 8640B with Option 323 and the standard 8640B What should be concerned about Also the differences between the URM 25D and the URM 25F One more question On my EAC from Fair Radio Z501 was cunched bad enough to break the phonelik tube supporting the core and winding was able to repair the damage and cosmetically it is quite good The DC resistance of the winding is 18 6 Ohms prior to and after repair The Y2K Manual Page 5 31 indicates DC resistance should be 4 8 Ohms believe that this is an error in the manual Z503 which has a similar winding measures 18 7 Ohms The Manual indicates the DC resistance is 18 Ohms for Z503 Need confirmation that my Z501 is OK before ordering another Z501 Date Tue 24 Oct 2000 10 24 45 0500 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 Re Test Equipment question There is nothing wrong with the 410C that know of hadn t noticed the C more available than the B around here Date Fri 24 Nov 2000 19 29 04 0500 From Jim Brannigan lt jbrannig optonline net gt test gear page 37 Subject Re R 390 Multimeter Any comments on the Hickok 1605M multimeter Fair has them listed in their current catalogue Would this item be a decent replacement for my tired old HP 410B Date Sat 25 Nov 2000 11 24 10 0500 From JM CO lt jmerritt2 cape
462. olve that problem with this cure That s what I m doing to my URM25D Date Sun 23 Jan 2000 18 03 35 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 SG 103 URM25F Question gt have a 25F and am curious wheather the same information regarding the gt D is appropriate to the F model I m a big fan of the 25F They re a hell of a lot easier to work on than the 25D or it s clones and use cheap as dirt dial lamps rather than the 323 s gt Since the F is newer have some of those problems been resolved in the later design Actually the 25F is newer AND older All of the 25F s that I ve seen were built about 1955 or so I ve seen D s that were built in the 1960 s In addition the later models like the 25G 25L etc are clones of the 25D Even though the 25F is different design with a totally different tube lineup it contains about the same number of potential problem capacitors as the 25D type The good news is that you can replace all of them in less than one tenth of the time that it would take to replace them in the 25D told you the 25F was easier to work on gt I d like to restore what makes sense in my F but not disturb gt components that don t need replacement do have a manual for the generator and see very few paper caps Drop me an email with the contract number and serial number of your 25F and the NavS publication number and date of your manual have a scanned supplement changes
463. om gt Subject Re R 390 Nixie Tube Freq Readout Methinks the term dog to be overly complimentary also have a Heathkit Tunnel Dipper and note its many problems Chief among these is its tendency to refuse to oscillate at all in the lower 1 3 of its dial range and an extremely touchy meter seting adjustment It really is much better largely confined to use even as an absorption wavemeter Date Mon 26 Apr 2010 01 30 11 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 Nixie Tube Freq Readout Really The only three ever liked were the 50s 60s VTVM V 7 V 7A IM 11 IM 18 etc after you drilled as few cooling holes in the case the DX 100 the original not the B and the W 5M audio amp before they changed the output transformer Everything else ever worked with or on could be described as nearly serviceable at best but always full of gratch I ve heard that some of the tube linears were OK but I ve never played with one Date Sat 24 Jul 2010 20 42 01 0600 From Transmaster lt 22hornet gmail com gt Subject Re R 390 R 388 lt snip gt You may have run into or own one of the many transmitter Receiver BC 22X XX calibrators which were used in the 1940 s and early 1950 s the one have is a BC 221 AL The R388 receivers where very accurate frequency standards in there own right and where used to calibrate the transmitters they worked with This one radio made the all of these HF
464. on dielectric precision capacitor sitting around Value is not real critical as long as it s in roughly the same range as the R390 capacitors Teflon caps have a very high insulation resistance Metal can parts generally last a long time You should be able to trust the markings on the part even 20 years later If the meter reads the indicated value and a very high insulation resistance say gt 50 gigaohms the meter probably is working just fine for R390 purposes There s nothing in an R390 that needs anything close to that kind of insulation resistance Date Sun 3 Apr 2005 08 47 00 0700 From Craig C Heaton lt wd8kdg worldnet att net gt Subject RE R 390 Speaking of TO 6As Just looked at the manual downloaded from BAMA s website Nothing in it on calibration or repairs but it does have a parts list and schematic Date Sun 3 Apr 2005 14 27 06 0700 From Dan Merz lt djmerz 3 cities com gt Subject RE R 390 Cap Leakage Hi Bob Dave Lee etal once again fine coverage here was thinking BAMA when someone mentioned TO 6a was used and that insulation resistance test gear page 120 was a standard measurement at least for the TO 6a instrument didn t realize that the only vintage capacitor checker ever had left my hands pretty quickly it was a cheaper variety and the only plus could see for keeping it was that it actually put high voltage on the cap when checking My interest was renewed by the discussio
465. once asked where the tube tester was and was told that TV repair guys used them because they didn t stock many spares and besides testers weren t conclusive We always had several new tubes of each type to try IMHO It s best to spend your money on a set or two of running spares to have on hand Most likely you ll need a few over the years anyway since the R 300 390A disease is usually severe and generally lasts a long time Date Tue 17 Sep 2013 13 14 46 0400 From rbethman lt rbethman comcast net gt Subject Re R 390 Tube Testers agree that THE circuit is the best place to test However have sufficient NOS spares for quite a few different radios So have one of those Hickock made Western Electric KSXXXXX testers am NOT giving it up Besides the price was right Take it home Bob Date Tue 17 Sep 2013 23 54 53 0000 From lt chacuff cableone net gt Subject Re R 390 Tube Testers Yep and that was back in the 70 s when tubes were young Now days many of the tubes use are really old NOS or in many cases pulls from other stuff over the years I m not fond of shoving a tube with a potential short into a radio without checking it before it goes in on something that won t go up in smoke and cause me grief The tube tester is good for that weeding out gassy and test gear page 411 shorted tubes sometimes NOS tubes that have been banged around for years now While agree the radio is the be
466. onnection questions gt One last note if you are measuring very low signal levels and have your counter hooked up to the High output on the URM 25 or similar output on the later HP 606 s you are fooling yourself and your receiver Agreed it would affect the calibration of the RF voltmeter circuit in the signal generator The amount would vary with the load of the counter Wait a sec Come to think of it think that it would be more than just the normal load of the counter Adding a second 50 ohm coax in parallel for the counter would totally change the output impedance of the circuit wouldn t it If so that could make a hell of an error in the calibration of the RF voltmeter circuit I ve chatted with dozens of different people about the military URM 25 series in the past Many of them use the thing pretty much as they got it and have never checked the calibration of the meter circuit Date Sat 08 Jan 2000 23 11 18 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Signal generator connection questions gt gt One of the URM 25D contracts NObsr 75083 came with an additional gt gt adapter the CN 530 URM 25D which was used to match the old 70 gt gt ohm input WWII RBB RBC type receivers that use the concentric style gt gt coax connectors A similar adapter the CU 408 URM 25F was supplied test gear page 282 gt gt with all of URM 25F contracts It s handy of you mess with the gt gt W
467. onsidered selling it in lieu of buying a 25 but might keep it if it will do the job guess what I m asking is does it suck for aligning the 390A Thanks Barry N4BUQ Panic Not If it radiates energy on a single narrow spectrum frequency and you can zero beat it against the BFO its good enough to align the receiver with The TM goes on and on about signal levels Worry not Do a relative test Measure the signal plus noise to noise do a change Measure the signal plus noise to noise again Compare the two values Your change either improved your signal plus noise to noise or it did not Undo the change if necessary and go on to the next item you have on the fix it list Remember the alignments in the RF bands are to get good flat response across the band At a flat response the exact point of test is not a do or die issue Run the receiver to the recommended frequency Set the BFO to zero Inject a signal and tweak the generator as close to zero as you can get Adjust the power level to a mid scale test meter reading Roll the KC know to peek the receiver to the generator Reset the power output to a mid scale test meter reading again tweak the adjustment under alignment Remember that for the crystal oscillators in the converters you are going for max output for the whole megahertz band So a specific frequency is not relevant in these adjustments The two places in the receiver where you would like real accuracy is to get the BFO to 455KHz
468. opy have had very good luck getting manuals Date Fri 21 Feb 2003 19 01 28 0600 From blw lt ba williams charter net gt Subject R 390 Hickok 600A manual wanted test gear page 78 Got one tester today a B amp K Dyna Quick 350 with tube data book I ll get the 600A on Sunday Does anyone know where to get the manual tube data tried BAMA already These were free so they have a new home here These testers came about from the free wanted ads that run most of the time brought home 3 boxes of good tubes from what saw saw some 6C4 and 6EW6 boxes in there There is a pickup bed worth of more tubes to get Sunday when it isn t raining so much Also brought home a Wurlitzer mono amplifier that uses 2 6L6s I ll get a Rockola amp with matching speaker on Sunday and more electronic goodies The guy said that he had a lot of TV and radio repair books to give me too From Al Parker lt anchor ec rr com gt Subject Re R 390 Hickok 600A manual wanted Date Fri 21 Feb 2003 20 34 32 0500 Hi Barry Sounds like a good haul I ve thought about doing those ads like a few guys do but the shopper here charges pretty hi for them Here s some stuff from my archives some is old info amp links might not work but first one is good There are schematics manuals and settings for this and other Hickock testers at http www 0Owned org hstraub hickok htm in the TESTER DATA data section In the ABOUT section there is
469. or long time gt I ve a bias towards Tek scopes from using 543 and 545 for a long time I ve been using my NASA surplus 547 for a long time When think scope think Tektronix gt But those aren t movable without a couple army troops or a couple mules Not that bad It s got two handles lt grin gt gt can move the 475 and paid for it hauling it to customer s locations even when was only looking at 60 Hz power problems like using a little Tek 503 for power audio use Only about a half a meg in bandwidth but it s cute and has a very bright and razor sharp display Using it in direct sunlight is not a problem like the tube input vertical amplifier when screwing around with voltages above line voltage too Much more forgiving One thing like about the old 500 series is the brightness and sharpness of the displays test gear page 25 learned a long long time ago is that you should never own just one scope If it breaks it s a hell of a lot easier to fix if you have another scope handy Been there and done that with the time base in the old 547 lt grin gt Date Wed 3 Jan 2001 21 48 17 0800 From Wayne Rothermich lt rother impulse net gt Subject Re R 390 R 390A Manuals and O Scope have a Tektronix 564 and also the Radio Shack probe scope The 564 has only 10MHz real time bandwidth even when you use the fastest plug ins and it uses relatively early storage tube technology The storage writing rate i
470. or 30 years We used to check the conductivity of the floors in the hospital operating rooms Cyclopropane was still used as an anesthesia gas You might guess it could be an exlplosive hazzard with electrosurgical units RF generators used as an electronic scalpel making lots of sparks Floors had to have their conductivity measured between two foil covered weighted electrodes 3 feet apart Acceptable readings Lower limit 25 000 ohms upper limit 1 000 000 ohms Just for the nostalgia cranked the handle this morning After all do own an R 390A Gary L Webb NI9V CBET III Clinical Engineering Specialist Date Wed 5 Aug 2009 07 54 32 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 Series 4 Megger Yup the local film producer the big yellow box used the same type of thing to check the conductivity of shoes in every building that had silver solutions in it Didn t want any stray static sparks to affect the light sensitivity of the silver stuff Date Thu 17 Sep 2009 21 36 07 0400 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 KA9EGW s n 4214 preliminary test results Not surprised you get signals all over the place AEA an N to BNC adapter There is a better way gt Suggestions I m halfway tempted to rip the C for an S0239 UGH Don t do that That C connector is part of the antenna relay here s what you can do get a twinax connector good ones can be had for 4 or 5 bu
471. or accuracy gt Equally good results are had with some surplus DEC Belden 50 Ohm gt double shielded extra flexible network RG 58 size cable Interesting never even considered trying any of the network cable gt have also found that clean BNC connectors with no tarnish are gt necessary for maximum performance have not tried RatShack or similar import gt connectors test gear page 275 As many surplus military and high end commercial connectors as there are on the market it s not work the gamble Date Fri 7 Jan 2000 20 51 42 0500 From km1h juno com Subject Re R 390 Signal generator connection questions gt When bought my URM 25F and 25G they both came complete with gt covers and all of the adapters cables fuses etc gt The MX 288 URM kit didn t come out until the 1960 s or 70 s gt The Navy version lists all the cover mounted items as part of the 25D not an gt accessory gt That is correct They were shipped together along with two copies of the tech gt manuals wonder what happened to all of the manuals It took me ages to track down originals gt gt CX 1363 U Test Lead actually a can with 2 BNC connectors Actually one BNC connector and two leads with alligator clips If you run into one of these make sure that you replace the blocking capacitor inside of it If it s leaky you can smoke the attenuator in the signal generator which is next to impossible to track down the
472. or to align my longwave beacon receivers as it goes down to 10kHz Date Wed 19 Dec 2001 17 30 35 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 URM 25D info YES The resistors and capacitors in the Twin Tee oscillator circuit have drifted You need the Overhaul Notes written by Dallas Lankford and published by the folks who publish Hollow State news Do not tear your generator apart without reading Dallas s notes DO tear your generator apart and replace all repeat all of the now leaking paper foil capacitors in there You ll be glad you did The circuit is very very close Mechanically they are quite different lt snip gt Date Wed 19 Dec 2001 18 08 29 0500 From Barry Hauser lt barry hausernet com gt Subject Re R 390 URM 25D info I m not the expert on these tho should study up as have a flock gaggle of URM s some of which need tending However looks like nobody has replied so far and can tell you this much Yes there are common failure modes concerning modulation with the URM 25x s When Fair Radio sells a checked unit they routinely replace 2 or 3 caps in that circuit When bought a reparable URM 25C a couple of years ago they threw in the caps with it but never got around to putting them in The routine for the D model is similar but different caps have an F model too URM s for all occasions That one still modulates as needed The C has the more common preliminary fai
473. oscillator in the counter and the frequency being measured at the time A 10 MHz master oscillator and measuring a frequency of say 15 KHz would show about 100 times less drift than a counter with a 1 MHz master oscillator being used to measure a frequency of 50 MHz gt Unless you dropped your new 0 95 Ramsey counter out of gt the tenth floor unto the freshly fallen snow of another gt Chicago blizzard it ought to be very much more stable gt than 50 Hz test gear page 311 lt ROTFL gt love it Date Thu 14 Dec 2000 11 01 54 0500 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 URM 25 Stability One thing I ve noticed is that they are very gt susceptible to instability caused by external mechanical forces CHECK THE SHAFT END PLAY had a URM 25D that would jump frequency if pushed pulled on the frequency knob It turned out to be end play caused by the rear shaft ball bearing load screw being loose 1 Get into the RF compartment and locate the rear end of the frequecy set shaft You will find a ball bearing whose clearance is set by an adjustable setscrew The thing has a locking nut 2 IMPORTANT Loosen the nut and screw a bit and CLEAN it with alcohol naptha acetone or some such Do not use finger nail polish it has oil in it for milady s skin Flux remover would be ideal 3 after a thorough warm up period set the end play so it just disappears no end play and no binding 4 Hol
474. oss to know where to find Bottom line is the cover is a fussy item If anyone has trouble with stiffness in the frequency adjust knob this post might help you If all else fails however there s always mayonnaise packets The crank knob had added to the unit makes frequency changes fly I m looking forward to lots faster alignments The knob is also a bit larger than the original although in the same shape and style For fun carefully removed the vernier skirt from under the original knob and drilled and tapped it onto the underside of the crank knob Looks factory cool Oh yes the parts unit works electrically perfectly frequencies are spot on Are BA s fun or what Date Wed 13 Dec 2000 20 00 00 0800 PST From Joe Foley lt redmenaced yahoo com gt Subject R 390 URM 25 Stability So my new freq counter says my URM 25D drops 2 kHz in 20 minutes after a 2 hour warm up period How bad is that If it was worse than that what would be the best place to start fixing it If its best to warm up an old tube for several hours before using it should also warm it up for a long time before testing it right Date Wed 13 Dec 2000 23 44 25 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 URM 25 Stability gt S URM 25D drops 2 kHz in 20 minutes after a 2 hour warm up period How long did you let the counter warm up Joe lt grin gt never checked the variance during warm up Is the drift consistent
475. ought I d post a follow up to this found a very badly botched job someone did of replacing a resistor in the plate circuit of the oscillator and finally got a replacement for it this week was thinking the resistor someone had used might have some inductance that was upsetting the circuit so replaced it with a carbon composition After replacing the resistor rechecked the linearity and it hadn t changed at least not significantly Someone suggested that reorienting the dial in relation to the tuning cap is the correct way to do this was skeptical since thought that changing the endpoint frequencies was equivalent to slipping the dial however gave it a try was pleasantly surprised to find this had a very signicant effect on the linearity The first test got me very close and the second attemp moving the dial a little more in the same direction got me pretty much within spec Worst case is 1 1 spec is 1 created an Excel spreadsheet with some charts that show the baseline deltas the before condition the changes after straightening one set of fins then the other set of fins and finally the curve after moving the dial Pretty interesting think if move the center point the linearity goes a bit negative and then a little bit positive think can get the entire dial within 1 Just thought I d report back in Maybe someone else will have the same kind of issues in the future so this might serve as reference m
476. out all over the bench now being re capped so a very good time to ask where one gets good double shielded RG58 style coax and good connectors like which particular BNC connector is the one of choice Took a look with a decent web browser and see only Times EMR 200 that claims to be 100 coverage with two shields Is that an appropriate coax or is there another suggestion Also thought saw someone who said he d bought some surplus double shielded HP cables If they re available where Interestingly enough with test gear page 278 all the electronics stuff flying around here in the Research Triangle Park area we don t have a decent surplus store that I ve found Maybe somebody in Silicon Valley or Route 128 land can suggest a place gt gt Equally good results are had with some surplus DEC Belden 50 Ohm gt gt double shielded extra flexible network RG 58 size cable Where does one find this stuff above gt It s amazing how much debris and oil film etc can end up inside gt of the attenuators in the URM 25 s I ve also seen contacts in gt them that weren t adjusted right or where dirty and would have gt measurable resistance levels Some as high as 30 ohms of so Not gt good for accuracy Nolan sure glad you mentioned the attenuator would never have thought of taking it apart I ve checked my URM25 against an HP 8405A vector voltmeter and find that the actual microvolt millivolt output reading isn t particularl
477. own of the cap Paper Caps such as Black beauties commonly show resistance of under 1 mega ohm which is clearly showing breakdown inside the cap New plastic caps such as orange drops show in excess of 150 mega ohms mica s show infinity Cranking the handle around 1 turn a sec produces the max out which is around 500 Volts which is good for many caps Slowing down the cranking speed reduces the voltage it is easy to crank out 200 or 300 volts for lower voltage caps One caution have a wire with allagator clips on the ends to short out the cap after testing a good cap will hold it s charge real well as have experienced this It can also be used for testing primary transformer windings before applying power coax cables etc They are available on ebay now and them bought mine for 10 00 and glad that did Date Sat 20 May 2006 15 26 11 0500 From Barry lt n4buq knology net gt Subject R 390 Capacitor Analyzers I ve read of the Sprague TO 5 s mentioned here Is there a preference for the TO 5 vs the TO 6 Date Sat 20 May 2006 16 37 10 0400 From Larry Kirkland lt Ikirkland sc rr com gt Subject Re R 390 Capacitor Analyzers test gear page 140 I m still using a TO 4 have an extra one gathering dust if anyone s interested Date Sat 20 May 2006 13 48 43 0700 From Kenneth G Gordon lt kgordon2006 verizon net gt Subject Re R 390 Capacitor Analyzers The TO 5 will measure turns ratios and imp
478. ownish ones should have written it down to note on the schematics Date Tue 25 Dec 2001 19 25 45 0000 From Phil Atchley lt ko6bb elite net gt Subject R 390 A URM 25D Success Story Howdy folks Since had time this morning before going to the In laws this afternoon decided to see what could do about my lack of modulation on the URM First thing did was to check the email responses I d received and check my junkbox YES had some nice new 1000pF 5 1000VDC silver micas On the 01 s wasn t so lucky But I did have some pull Mylar 01 s at 630 Volts checked and found a couple reasonably closely matched Next pulled the unit out of the case and surveyed the matter It quickly became apparent that this wasn t an easy task to do in the precise remove and replace way that like to do things So get out the long nosed dikes splice some wire onto the capacitors the pulls had come from a PC board the NEW ones had short PC board leads also and then splice the replacements into the original leads NOT the way like to do things Fired her up and voila have modulation and nice clean sounding tones of 400 amp 1000Hz or was it CPS in those days This unit was supposedly overhauled by Tobyhana in 1983 must presume that overhaul didn t include capacitor replacement unless they were known bad Man dig all that cast metal in there Now know why the Navy liked these things Run out of shells Load a f
479. page that may apply to your manual and signal generator and can attach it to you It s about 200K gt have heard about the other types Micamold Ceramic lakage problems gt and am curious about other s experience with the F model Same Better Worse Ect There are a series of metal cased rubber sealed axial leaded paper capacitors in the URM 25F that are prone to give problems Most of the ones I ve seen were made by FAST They re a hell of a lot better cap than those micamold paper caps in the 25D but change them all test gear page 299 Most people ignore them because they think that they re a glass and metal sealed cap but they ain t In addition make sure that you replace the 047 blocking capacitor in the CX 2919 U test adapter It s leaky or will be soon gt currently have a problem where my modulation drops out after the gt equipment is on for a while do use this for R 390 alignments as gt well as other restoration work On topic association I ll bet you a beer that it s a bad capacitor A quick run down on the capacitors that I d change in a 25F even if it was working are C602 on the power supply C130 C131 C132 C133 C134 C136 C139 C141 and C142 on the big board C121 and C116 on the small board Also you might want to remove C114 the 120 mf electrolytic can that s clamped next to the 6AG7 and test it Reforming it at its rated voltage couldn t hurt I ve also seen a sprinkling of fail
480. pe can attest to the fact that 5000 and 7000 series plug ins are not compatible have a 7000 series plugin that bought cheap at a hamfest Someone had test gear page 17 forced it into the wrong connector was told that the wrong connector was in a 5000 series scope Now the plugin will work in neither Date Fri 02 Jun 2000 21 04 48 0500 From Tom Norris lt badger telalink net gt Subject R 390 RE DQT Was Need Advice on O Scope The specs used in out PME lab are fairly simple just hook the scope to the scope calibrator and press a button errr Well on scopes with IEEE ports we can do that On normal scopes we usually use the point where it rolls off to 95 of the lowest freq reading usually 50Khz as the maximum bandwidth Sync is tested separately and if it will not sync at spec ed bandwidth the bandwidth is limited to the highest sync freq and noted as such for the user If a 250Mhz scope will not sync above 175Mhz then it is no longer a really a 250 Mhz scope Just some more non 390 related scope trivia for the bored Date Sat 02 Sep 2000 08 09 16 0500 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 O Scope gt what is the best scope for BA s Tek 465 with Tek probes Date Sat 02 Sep 2000 10 02 55 0500 From Randy amp Sherry Guttery lt comcents mississippi net gt Subject Re R 390 O Scope I m sure you ll get the usual Tek 465 adv
481. pect that is still the case For one thing they make low C probes with special low loss coax and they provide superb compensated attenuators where the RC time constants of the two elements of the attenuator are totally matched or can be by proper calibration would not recommend any other brand than Tek s own probes You can t really go wrong with them but there are some that afficianados will say are less good than others Date Fri 26 May 2000 21 49 52 0700 From Larry Shorthill lt rfssi shorthill mindspring com gt Subject Re R 390 probes The Tek 5000 series was a lesser cousin to the 7000 series of scopes It was the economy version and doesn t have near the performance although it came out about the same time Also the 900 series of scopes was built like an Electrolux vacuum cleaner in size and shape It was the bastard child of the Tek lines It was portable but not distinguished If you want a real bench scope aside from the 54x especially the 547 the 7000 series especially the 7704 and several others are prefered If you want a portable scope of that era the 454A and the 475 and 485 are great Inside Tek the 465 was considered very fragile and not a favored variant the rookie engineers always got the 465 s because they were prone to breakage and because they sucked in general Also the TM500 series of instruments were not very robust had a bench full of the TM500 mainframes and plugins and about 50 were br
482. per All way overkill for the hobbyist though too expensive except mayby the 500 Date Sun 15 Feb 2009 20 54 36 0600 From Jim Shorney lt jshorney inebraska com gt Subject Re R 390 test equipment question I ve got an IFR1000A that have to whack once in a while OK for FM work but not really stable enough for SSB It needs a good cleaning and probably caps Do any of you guys know how to fix a Com 120A Stole one at an employee auction and it worked for about a month Won t boot now just beeps at me Haven t had time to crack the cover Date Sun 15 Feb 2009 22 24 11 0500 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 test equipment question gt One reason the Wavetek is so cheap is that it is a 75 ohm output device not meaning to sound sassy And this makes a difference how Date Sun 15 Feb 2009 21 41 52 0600 From lt wb5uom hughes net gt Subject Re R 390 test equipment question Well have a 120A and a 120C and don t consider them junk and waiting on the new Aeroflex 3920 to arrive Have very little trouble out of either but the maint agreement sure helped every now and then Date Mon 16 Feb 2009 20 49 48 0500 From bonddaleena aol com Subject Re R 390 8640B gear question Hi I ve really enjoyed the discussion about vintage test equipment too enjoy collecting TE and working on them as much as my vintage radios am fortunate because I ve been collecting thi
483. ple leaf springs just take a couple out don t know if it s endemic but it had several cracked nylon gears and plastic switchplates was able to repair them but those little contact fingers are hard to keep track of when they fall out glued them back on with epoxy Option 001 is a variable frequency modulation source very handy You may be spot it in a photo look for a viewing window in the second knob from the left Option 002 extends the frequency to 1024MHz Option 003 is reverse power protection to 50W These have a stick on label above the RF Out connector Option 004 is an extra precise step attenuator and modulation cal The single big rotary dial at the right is replaced by two smaller ones sort of side by side Date Fri 25 Feb 2005 22 20 09 EST From DJED1 aol com Subject R 390 URM 25 replacement For the last 5 years I ve beeen doing my alignments on my R 390A with a URM 25 got from Fair Radio It s worked OK as long as put a frequency counter on it to get on frequency But as was repairing it a couple of weeks ago saw that it was from 1952 and decided it was time for an upgrade after 50 years of service looked at the HP signal generators on the e place and test gear page 352 picked up an HP 8660A for only 300 not bad for something that cost 25 000 when it was new The R 390s certainly hold their value better think they only cost about 2000 new and are worth over 500 now Anyway it s
484. pper crew did not remove the old elctrolytics but merely scabbed in the replacements So measured the resistsances of the old electrolytics with my DVM They seemed fine no shorts no leaks reasonably high resistance after charging for a while Later will actually power up the electros with a DC supply and check the m for leakage under operating voltage If they pass that test will remove the replacements and restore the originals gave seen this kind of thing before in a Hammarulnd HQ 180A Fortunately that zipper crew also left the old electrolytic can in place and restored it Have fun Dallas Date Mon 10 Jan 2005 20 43 26 0500 From Bob Camp lt ham cq nu gt Subject Re R 390 Servicing Advice on Signal Generator URM 25D asked this back a few years ago and maybe it s time to ask it again Has anybody seen any of the black or brown body epoxy coated paper and foil capacitors made in the 1950 s and 1960 s show up good As originally asked the question was specific to the R 390 Since then have seen a bunch of posts on a number of reflectors about these parts They all seem to indicate these parts are a problem At least in my experience testing pulls from a couple dozen radios they show up leaky as in 5X out of their original specification roughly 80 of the time They show up at least 2X the specification gt 90 of the time Certainly there are places where you will not notice leakage even if it is 5X the sp
485. problem I d pass Date Tue 11 Jan 2011 20 41 32 0500 From wa4aos aol com Subject R 390 8640B Yes As Don has pointed out TWICE the external reference for the 8640B is 5Mhz and 10 Mhz as had mistakenly stated earlier sorry for my error made that conversion in my distribution box for a number of HP units have that require 5 Mhz external reference as opposed to 10Mhz used on many other devices in my lab My point was to give my two cents worth with regard to the quality of the 8640B as it pertains to most HF alignment issues It s a very good sig generator and can be bought at a reasonable price It s great for almost any application that have needed it for during the last 10 plus years that have been restoring receivers Since we need to NITPICK the 8640B does NOT go much below 450 Mhz out have two 8640 s that go to around 435 and two that go down to about 445 Perhaps revision differences have the option that allow all of my generators to go above 1Ghz If you are working on receivers with lower IF s and need to do alignments then another generator will be best With regard to blowing up the internal counter by over driving it The owner can adjust the input level accordingly with an attenuator However for most of my applications have not had to attenuate an input signal would expect most users of such equipment would be INTELLIGENT enough to not exceed those parameters without the need to install a plug to preve
486. quency The 606A B is big heavy and takes up a lot of bench space Date Tue 17 Jan 2006 16 34 08 0800 PST From Joe Foley lt redmenaced yahoo com gt Subject R 390 Bulb NSN Does anyone know the NSN for the bulb in the URM 25 s Date Tue 17 Jan 2006 19 55 12 0800 From Craig C Heaton lt wd8kdg worldnet att net gt Subject RE R 390 Bulb NSN Looking in one of my manuals AN3136 323 Lamp incandescent 3V 190 ma bulb T 1 1 4 clear 35 64inch Ig o a special screw base C 2R tungsten filament burn any position This is for the dial lights Don t know if anyone still makes this lamp do believe Ashley Hall on that e place has some VO 16 Lamp neon 105 125V 1 25W bulb T 3 1 4 clear min bay s c burn any position This is for the ON lamp Date Thu 17 Aug 2006 11 31 35 0400 From David C Hallam lt dhallam rapidsys com gt Subject R 390 URM 25D SM 35 Antenna Simulator am going to build a SM 35 antenna simulator for my signal generator It uses a 20 uH choke which is no longer a standard value Will a 22 uH choke make any difference suppose could put 2x10 uH in series Date Sat 19 Aug 2006 09 05 43 0400 From WD9INP 4 lt WD9INP isp com gt Subject URM 25D SM 35 antenna simulator test gear page 359 Go ahead and use it That s a 9 variation Date Mon 28 Aug 2006 21 08 37 0000 From eldim att net Subject Re R 390 DA 121 U Dummy Antenna If memory serves me correctly
487. r VR tubes OK after spending several nights and a half a fifth of Rebel Yell studying life in general it appears that the settings used by the TV 3 and TV 10 series testers are identical Why the settings data for voltage regulator tubes was not included in either the manual or roll chart for the TV 10 series tester but was included in both for the TV 3 series tester will probably remain one of life s great mysteries The voltages supplied by the power transformers in both the TV 3 and TV 10 series testers looks to be the same So here s some settings that you guys with TV 10 s can try This is purely experimental so if you put an eye out or create a black hole and destroy your town or something don t come bitching to me The format is the same as the roll chart so didn t bother to type the column headings in OA2 BLST KRO 3020 0 42 A P4 Volt Reg Read As Rectifier OA3 JPO 5010 0 67 A P4 Volt Reg Read As Rectifier OB2 JPO 5020 0 42 A P4 Volt Reg Short on 3 Read as Rectifier OB3 JPO 5010 0 69 A P4 Volt Reg Read As Rectifier 0C3 JP0 5010 0 65 A P4 Volt Reg Read As Rectifier OD3 JP0 5010 0 46 A P4 Volt Reg Read As Rectifier 5651 APO 3070 0 56 A P4 Volt Ref Read As Rectifier 5783 APO 3050 0 72 A P4 Volt Ref Read As Rectifier test gear page 49 5787 BLST JPO 3010 0 67 A P4 Volt Ref Read As Rectifier 5823 BLST AP8 3010 100 87 A P4 Volt Reg Read As Rectifier Holler back with
488. r a missing accessory That s it for now Hope didn t bore anybody Date Tue 8 Jun 2004 15 16 13 0400 From Jim Amos lt jimamos cisco com gt Subject RE R 390 SG 25 bought a URM 25 C at Dayton in which the modulator didn t work It also turned out to be one of the paper capacitors After replacing the cap everything worked great It was one of the ones that was part of the oscillator function and not a coupling capacitor Date Mon 12 Jul 2004 16 03 01 0700 From Dan Merz lt djmerz 3 cities com gt Subject R 390 DMM bounce Hi here s a general question related to making resistance measurements when an inductance is involved e g the winding on an audio transformer Generally make such measurements either with my BK DMM on a fixed scale setting or with a Simpson 260 old style multimeter and usually have no problem But recently repaired an audio transformer and sent it to the lucky guy and he emailed that the primary was ok but his digital meter just bounced on the secondary and never settled on a reading thought maybe made a bad solder connection The approximate inductance of this secondary is about 360 henries He sent it back to me and measure it as ok about 1500 ohms test gear page 105 using my usual methods do notice that the reading shows a couple of high reading before settling down This doesn t happen on the primary which is much lower inductance My question are there some DMMs maybe
489. r filter could be eliminated and power borrowed from the R 390x by means of a tube socket plug or clip leads fuse protected of course The aforementioned site has settings readings for testing many tube types more can be found at another audiophile site triodeel com Date Tue 26 Oct 2004 21 14 15 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 Tube Tester certainly will not argue that a tube tester is a perfect gizmo A working radio will always be a better way to check a tube than any tube tester made That said a tube tester does have it s place If you have a dead IF strip on your only working radio you need to start with something DC voltages are one way to go a quick run through the tube tester to find a dead tube is another way to go test gear page 112 Probably the most use have ever gotten from a tube tester was on a piece of gear that had been run so long with the same set of tubes in it that they all were low gain Not a single tube in the set made it above about 1 4 of the minimum good reading on the tester Needless to say with every tube in there near dead troubleshooting the thing was a bit much The thing that bothers me the most is that pretty much all of us spend a lot of money on tube testers that do so little for us Date Tue 26 Oct 2004 21 59 19 0400 From Bob Camp lt ham cq nu gt Subject Re R 390 Best R 390A Tube Tester The reality of a tube tester is actually worse th
490. r friends during which process learned more than really wanted to know about them They are not easy to work on Stability is decent never measured leakage but never noticed any problem in this regard The 8601A has a fair degree of line hum mostly 120 Hz that appears as FM on the RF output found it was virtually impossible to remove If having a sweep generator is one of the reasons for considering the 8601A its sweep mode is pretty clunky The calibrated sweep widths in symmetical sweep mode only go down to 100 kHz above 11 MHz and only to 10 kHz below 11 MHz so you re left to use the vernier and guess how much sweep you re using for most radio alignment tasks Like many RF generators the attenuator is not well protected against overload so you need to be sure nobody ever transmitted into it which for some reason is much more common than I d expect My advice for anybody who may ever hook up a transceiver to a signal generator is to leave a 20 dB coaxial pad permanently installed on the generator output Date Sat 24 Apr 2010 22 26 24 0400 test gear page 223 From jrfke5ri aol com Subject Re R 390 Nixie Tube Freq Readout Many years ago Heathkit made a tunnel dipper It was a real dog compared to Millen tube type meters still have the darn thing and it works but don t use it Perhaps should offer it on e bay Date Sun 25 Apr 2010 15 01 15 0700 PDT From Drew P lt drewrailleur807 yahoo c
491. r in it s own right From Don Reaves W5OR lt w5or comcast net gt Subject RE R 390 Signal Generators was Deoxit Date Sat 29 Nov 2003 11 18 46 0600 second the HP 606 boatanchor nomination especially the HP 606B model It has a high level secondary output independent of the calibrated output that is useful for connecting to a frequency counter As Cecil says they are built like tanks and the only trouble I ve had with mine is that the grease in the band turret got old and gummy and finally prohibited easy band changing used a degreaser to soak out the old grease over a period of a week and then applied new lubrication Works like new Be careful buying signal generators they often have the attenuator fouled up and you will need a functioning calibrated output for tweaking your R 390 The URM 25 is the genny called out in the manuals They are much smaller and compact and a bit harder to work on should you need to repair one But it is the classic choice I ve never owned an 8640B but you can trust Walter s recommendation 8640s are on the workbenches of Chuck Ripple and Rick Mish Be sure you get one that does not have the attenuator burned out A friend who is tuned into the used test equipment market says prices for high quality older test equipment are just absolutely sinking So it s a great time to upgrade your workbench At a recent Texas hamfest test equipment was nearly being given away For example picked
492. r some tube extenders Date Sun 07 Aug 2005 06 27 28 0400 From Barry Hauser lt barry hausernet com gt Subject Re R 390 tube testers gt circuit that the tube is in That s true and many of the tube tester manuals say so another YMMV disclaimer Tube extenders are well worth having though some are a bit too big to fit some places in R 390 s You might want to roll your own but it s not easy to find 7 and 9 pin bases There are various tradeoffs in tube tester design so they may be more accurate with some types of tubes than others and there can be errors in the tube charts The manufacturers did not necessarily calculate the correct minimum reading for every number Many of the entries were probably determined through extrapolation interpolation if that Or they cheated and used a conversion factor on the values from some other tube tester And of course what s good enough in one socket in a particular piece of equipment might not be in another for the same tube number YMMV prevails Tube testers do have their uses such as Sorting through batches of old tube finds Pre testing for shorts grid emissions burnt out filaments before installation Making relative comparisons matching or selecting tubes such as tubes that should not be too hot Checking for burnt out tubes that are part of a filament string Yeah you could do that with an ohmmeter moving the tube extender aroun
493. radio simply fails or smokes _ when the substitution is made On the whole my own preference is to use a tube tester of some kind Date Tue 26 Oct 2004 13 02 21 0400 From Veenstra Lester lt lester veenstra Imco com gt Subject RE R 390 Tube Tester While tube testers are fine for gross checks an evaluation of real goodness that is gain at RF or at IF or at AF or IF AGC Action or and particularly front end noise is best done by substitution in the receiver finding better best or in many cases does not make any difference tubes The exercise of testing nominally good tubes in a tube tester and using that data as a predictor of which is the best in a critical spot in the receiver is not one would waste time with Of course all the above is predicated having a receiver available that is in reasonable good condition From that point running substitution checks with the available stock is a way to get reasonable condition up to really hot condition Still would like to see design of the 1 95 do it yourself tube tester Date Tue 26 Oct 2004 10 26 45 0700 From Doug Millar lt dougnhelen moonlink net gt Subject R 390 Best R 390A Tube Tester The best R 390A tube tester is a set of substitution tubes Most tube testers only measure tube performance at low frequencies and may not give a good picture of what the tube is like am trying to find an article written in the 50s test gear page 111 that d
494. rarily then do need to account for the forward voltage drop across it Does the EA53 and or 2 01C have a similar voltage drop so it won t be an issue For larger voltages it wouldn t matter but on the low ranges it might be an issue Date Fri 29 May 2009 20 53 31 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 Parts Request Yes You can minimize this by using a germanium diode preferably gold bonded or Schottky diode in either case use a small signal diode The forward drop will affect the low voltage ranges more than the high voltage ranges but note that germanium and Schottky diodes have rather low reverse breakdown voltages gt Does the EA53 and or 2 01C have a similar voltage drop 000 don t have curves for the EA53 and 2 01C handy but indirectly heated small signal diodes operated at very low current generally start to conduct when the plate is slightly negative WRT the cathode A 1N34 would be one of the likely candidates and it has a reverse voltage rating of about 60 V IIRC Why not use half of a 6AL5 Those are good for 330 PIV The 6H6 the once common octal dual signal diode has a PIV rating of over 400 V Best regards Don Date Fri 29 May 2009 23 50 33 0400 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 Parts Request A kind list member did have data handy for the EA53 and it appears that it draws 1 uA when the plate is 0 5 V negative yes it
495. ration Fixture surplused by the local FAA cal facility very cheaply because the junque dealer wasn t sure what it was or if it worked and didn t think he could sell it very easily He got it in a pallet load of more common and popular stuff Don t recall the Tek model number offhand but it puts out or DC voltage plus a perfect looking p p calibrated square wave from tenths of millivolts up to 200V in 20 steps and also has a single value 5 milliamps think current calibration output DC output appears to be extremely accurate when matched against a couple of new calibrated Fluke and Wavetek DVM s probably more accurate than either meter actually although the unit was last calibrated by the FAA lab over 4 years ago The square wave appears to be spot on also when compared to two different Tek scopes neither of which have been calibrated since George Washington was president Doesn t take up much shelf and has turned out to be extremely useful around the bench Date Thu 14 Dec 2000 08 45 00 0600 From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 URM 25 Stability test gear page 309 recently did a partial rebuild of the HF module in my signal generator AN TRM 1 replaced suspect caps and out of tolerance resistors When put it back together found that if simply breathed on the oscillator section it would change frequency by as much 1000cps or more Certainly something is temerature sensit
496. rator left a bit to be desired The URM 25 was originally used with the R 390A and is available at reasonable 100 200 price If you want to take a step up in the generator you could go to an HP 606 tube type which is a real boatanchor by itself still have my URM 25 but moved up to an HP 8660A 300 which was the first of their solid state synthesized signal generators can trust the signal levels a bit better than the URM 25 and the frequency readout is infinitely better also picked up an HP AC voltmeter to use in measuring the signal and noise in sensitivity measurements and a HP frequency counter mostly for setting PTOs The VTVM can serve the same purpose as the AC voltmeter also have an inexpensive tube tester guess the only other test item that I m looking for is a capacitor tester which will then allow me to check every kind of component in the radio Good luck in your search Date Sat 26 Jan 2008 10 20 06 0800 PST From wli lt wli98122 yahoo com gt Subject R 390 test equipment recommendations The list has provided a comprehensive listing of test equipment for you use a BNC T connector off of my URM 25F and use my frequency counter as a readout of this venerable RF generator Should mention that a real VTVM is what you need at the diode load not a cheapo digital high impedance voltmeter Capacitance values may be measured using simple 555 timer circuits But for capacitor leakage measurements you
497. rd HP 410 C VTVM No Chuck you mixed it up this is true for the Boonton RF Millivoltmeters Model 92 or something but does not apply to the HP 410B and HP 410C Also check the manual there is nothing written about not to change the probe You have to adjust a pot inside the meter to set the filament voltage but that s all you need to do The voltage is either 5V or 6 3V depending on the tube 2 01C or EA53 used in the probe have acquired a separate probe on eBay much cheaper than a 2 01C from AES for the HP 410B which was still sealed in the military packing and it works exactly as the original probe The probe for the HP 410B is wired to a terminal block underneath the instrument The probe for the HP 410C has a standard 1 4 plug The schematic for both probes looks identical Check eBay for probes or a broken HP 410B HP 410C with probe have seen both going quite cheap From Rob Dunn lt robdunn1 earthlink net gt Subject Re R 390 FS Hewlett Packard HP 410 C VTVM Date Mon 14 Oct 2002 14 10 19 0700 don t believe this is true do know that the 410C could be purchased with or without the AC probe and the AC probe could be purchased separately as well can believe that the calibration is only valid for a specific probe paired with a specific meter to account for variations in the vacuum tube UHF diode characteristics but the 410C is very easy to recalibrate and the procedures are in the manual have a 410C and it develope
498. re A B C D E F and a G There was also a civilian model There were many other flavors We should have a link to a schematic for each model on your R390 pages Maybe they should be an add on to the Y2K CD The tube set did vary from model to model The internal drum tuning section mechanical vary from model to model The later models are considered better than early models The best change is to solid state the rectifier tubes like we do with the R390 s This of course changes the B and frequency So you need to re calibrate This change does get a heat generator out of the case and lets the unit run cooler The D models are considered Good No problem keeping any of them running Check the tubes every 4000 hours and calibrate whenever the signal gets so far off the dial number you cannot stand it any more replace the dial lights as needed Watch for the blue gas glow in the tubes The tubes will still test good in a tube checker But get them out of the signal generator New tubes will drift Just leave the generator on for several days to cook the new off Microphonic and noisy tubes are my worst problems You can hear the generator noise in the receiver headphones when you bump the generator around on the bench This noise is not a problem Roger AI4NI Date Tue 28 Nov 2006 23 38 31 0500 From Mark Huss Subject Re R 390 Differences between the various URM 25 generators test gear page 361 We taught that unlike most mili
499. re else Rainer Foertig http www rainer foertig de unterlagen hb htm has it available for EUR 48 40 which is about 70 http www rainer foertig de unterlagen RS 30_2010 htm bought a couple manuals from Rainer in the past and they are high quality xeroxed copies No connection just a satisfied customer Contact Rainer at lt archiv rainer foertig de gt may be able to assist you if you have any difficulties with the transaction am about 20 minutes drive from him Date Tue 5 Jul 2011 08 19 21 0500 From Ben Loper lt brloper gmail com gt Subject R 390 TV 7 lid gasket Does anyone know where can find the rubber gasket material for a TV 7 test gear page 375 tube tester lid saw it before and have checked several websites but can find it The orginal gasket is about 1 4 wide and has a V shaped groove Date Tue 5 Jul 2011 19 51 12 0500 CDT From nryan mchsi com Subject Re R 390 TV 7 lid gasket think it s called welting I ve not tried this on a TV 7 but you might want to check out the aftermarket stuff used to protect car door edges found some at WalMart that works fine on my car My material came in strips think you may need two of them to go around a TV 7 s lid Have a look in a Super Store automotive section or an automotive store and check if this might work for you Best of luck and let us Know what you find Date Wed 6 Jul 2011 23 52 31 0600 From Transmaster lt 22hornet gmail com gt
500. read exactly what the lab standard read for that tube Note that the tube would only have to drop to about 70 of its new tube value before it reached the bottom of the area and start to be rejected That s why a lot of tubes that test in the fail or reject part of the scale still work in equipment Remember tube manufacturers wanted to sell tubes and it was test gear page 128 better to err on the side of conservatism better to throw away a still usable tube than to keep a bad one When was doing this back in the middle 60s there were only about 3 4 models that had their roll charts upgrated with the new tube types There was also that cardmatic one that got the new types If you wanted data on a tube for an older model that didn t have it on its roll chart all you had to do was call customer service remember dragging those oldies out of the morgue and getting the settings for a customer or two A new cardmatic model was also being develolped for the military but don t think that ever got pass the prototype stage remember doing the layout on the power supply pc boards for those By that time tubes were on their way out Introducing new tester models was a nightmare you had to go and verify every tube type with the new tester settings spent many an hour doing that on their mustang model Kind of boring but lots of overtime enough rambling pete KH6GRT Date Fri 12 Aug 2005 07 46 21 0500 From Cecil Acuff lt
501. red with a large probe with sensitivity of 0 5V FS to 300V FS 2 accuracy from 100 Hz to 50 MHz 4 from 50 to 100 MHz and 1 5 db from 100 to 700 MHz from the 410C manual There s also a useful AC probe adapter that converts it from a 1 2 spike tip to a shielded pair of N connectors for placing in a transmission line So to measure audio signals get a 400 To measure transmitter output voltage and calculate power into a dummy load get a 410 From scott lt polaraligned earthlink net gt Subject Re R 390 Tube testers and other babblings Date Sun 18 Aug 2002 08 54 51 0400 Your B amp K tester is a good middle quality mutual conductance tester that should serve you well lt snip gt From Scott Barry Clyde B lt cbscott ingr com gt Date Thu 29 Aug 2002 08 54 01 0500 Subject R 390 Audio Signal Generator question An HP200CD followed me home from the local hamfest recently figured it was worth 15 since it was working plus it matches my HP410B It is a 200CD model Last night someone was advertising a 200AB on Ebay a very nice looking one at that Is the CD a later version of the AB Is that only difference Anyone From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 Audio Signal Generator question Date Thu 29 Aug 2002 10 41 39 0500 Great NOW you tell me it has expensive output tubes sigh lt g gt gt No The C version uses a different pair of output tubes and te
502. related items were published in the HSN periodical 2 If you have a URM 25F these overhaul notes may be quiet helpful but the F model is laid out differently so some adaptation will have to be made Years ago had an email exchange with Dallas in which he indicated that he had never made a corresponding set of notes for the F model Date Wed 7 Mar 2012 02 00 35 0500 EST From jrfke5ri aol com Subject Re R 390 Capacitor tester test gear page 396 IO have been using a Sprague Tel Ohmike Capacitor Analyzer model TO 6A for many years like the fact that it can also be used to see if electrolytics can be SALVAGED disconnect one side and slowly raise the applied voltage keeping the current within reason If can reach the specified voltage and have leakage current also within spec feel fairly safe in keeping the old capacitor This is also an excellent way to safely re form them Date Wed 07 Mar 2012 08 53 22 0500 From rbethman lt rbethman comcast net gt Subject Re R 390 Capacitor Tester Miles makes excellent points They are certainly not erroneous It becomes a matter of how one chooses to perform tests The Brown Beauties are definitely prone to failure and are essentially a known and automatically get replaced That being said This also is why it is important to know precisely which radios were built by whom and the specific date of contract 67 EACs do not have the aforementioned BBODs Brown
503. rements over a wide range of frequencies is quite involved Careful study of the specifications of the HP RF voltmeters and similar general use laboratory quality instruments will give an indication of the accuracy attainable in production equipment A look at the following URL which explains the RF voltage calibration services available at NIST reveals that at 100 MC and above peak to peak detectors can be calibrated to 1 2 percent No one in the country can do better Think about that next time someone reports the sensitivity of a radio receiver to two or three significant digits http ts nist gov ts htdocs 230 233 calibrations Electromagnetic Voltage htm 534 3 An AC voltmeter that works well up to frequencies beyond the range of the URM 25 is simply not necessary Date Mon 24 Jun 2002 18 35 17 0400 From Jim Brannigan lt jbrannig optonline net gt Subject Re R 390 URM 25D recap test gear page 339 I ve checked my URM 25 output against my HP 410 C and Tektronix scope various frequencies etc The numbers all sorta agree close enuf for government work agree with Roy have a shop not a lab I m more interested in relative readings than absolutes Repeatability and comparison from a shielded controlled source at a known resistance is important For example If a 2 on the URM 25 voltmeter produces the same output on two different receivers they have the same gain If a 2 at the RF stage produces the sam
504. resistors for It is included with mine tnx for the heads up gt gt UG 684A Connector adapter BNC one side 1 4 phone jack the other gt One of the URM 25D contracts NObsr 75083 came with an additional gt adapter the CN 530 URM 25D which was used to match the old 70 gt ohm input WWII RBB RBC type receivers that use the concentric style gt coax connectors A similar adapter the CU 408 URM 25F was supplied gt with all of URM 25F contracts It s handy of you mess with the WWII stuff worked on the RBA B C series for many years along with the 25D liked those sets Hated the later SRR series and the URC 32 very unreliable always crapping out on the mid watch Also the damn Model 15 TTY clunkers when they switched to 100 WPM gears for the new Crypto units Finally replaced with 28 s gt gt also have 8 pages of notes that Dallas Lankford sent me in 1988 gt A large SASE gets them gt gt already have them wish I d have had them when I received my gt first 25D it would have saved me a hell of a lot of trouble shooting to find the bad capacitors The capacitors that Dallas said to change lt grin gt Actually had intended to copy the list which is why mentioned the SASE didnt want to get bogged down with 100 orders at 55 a pop I ll copy this msg and see what happens Maybe everyone already has the info gt gt You guys are getting me wound up maybe its time to open up this test gear page
505. responded with the must vulgar language I ve ever heard I m sorry to say he is a ham too Guy actually charges a shipping fee for a download he is selling He does not even provide a CD He gets it from BAMA and puts it on his server then charges the uninformed for the priviledge of getting it from him reported him to Ebay and HP Date Sun 07 Dec 2003 08 59 39 0500 From Tom B lt tobryan nova org gt Subject Re R 390 Signal Generators was Deoxit 8640B Manuals are also available from the Army website at Parts https Awww logsa army mil etms data A 022731 pdf test gear page 97 Service https www logsa army mil etms data A 060577 pdf Calibration https www logsa army mil etms data A 063108 pdf The 8640B manuals are freely available to the public but they are large files lt snip gt Date Sat 31 Jan 2004 07 26 11 0600 From Jerry Kincade lt w5kp direcway com gt Subject R 390 Cushman CE 15 Spectrum Monitor Manuals Lots of these excellent monitors are still out there working in shops but found out the hard way CE 15 manuals are extremely difficult to find now have a limited number of clean sharp 1st generation photocopies complete with all foldouts schematics and parts lists 3 hole punched and assembled ready to drop into your 3 ring binder 30 shipped to your door via Priority Mail anywhere in the lower 48 Please email me OFF LIST if interested Thanks From Sam Doughty lt sdman cableone
506. ri 31 Aug 2001 12 50 41 EDT From Llgpt aol com Subject Re R 390 DMM probes load the test points That s the truth Roy a TS 505 or the TS 352 all work very nicely in that regard DMM s are hardly ever used by me anymore with the exception of certain applications Date Mon 03 Sep 2001 12 34 30 0700 From Daren lt redbeard softcom net gt Subject R 390 Opinion on HP 606b sig gen went to the Livermore Ca radio puter swapmeet yesterday and found a drop dead beautiful HP 606b signal generator I m a beginner at all this and will basically have to teach myself the ins n outs of it s use He was packing up just as talked to him and said the price was 200 From what I ve found on the web so far the price is a little bit high but not out of line and think he would deal down a bit No manual or leads are included What say the clan Also picked up 3 VTVM s w out leads or manuals 1 HP 400d and 2 more HP 400h s One 400h was last calibrated by the Navy in mid 98 gave the guy 20 bucks for the 3 as he was closing out his biz and moving on to greener pastures Once again I m going to have to teach myself about their use figured the best way to learn this stuff is trial by fire The VTVM s are a done deal but wanted to check with youse guys before making the final deal on the signal generator I ve got broad shoulders so if deserve to get smacked around for stupidity can take it Lemme know w
507. rint icon on the DjVu toolbar It works now Thanks to all who replied From Glen Galati lt eldim worldnet att net gt Subject Re R 390 Audio Signal Generator question Date Thu 29 Aug 2002 12 20 39 0700 Hello Barry amp Crew Nice Find on the HP 200CD The 200AB is a lower frequency version 20 Hz to 40KHz vs 200CD 5 Hz to 600 KHz This line of Audio Oscillators is one of the best and most popular ever manufactured by H P Both are Vacuum Tube types with this version in production more years than one can imagine It was in my 1963 HP Catalog at a cost of 195 vs 165 for the 200AB Output level on the 200 CD is 10 Volts into 600 Ohm Load The 200 CD is very nice for doing IF alignment and tests and of course for all your audio work test gear page 68 From Bill Hawkins lt bill iaxs net gt Subject RE R 390 Audio Signal Generator question Date Thu 29 Aug 2002 21 37 51 0500 Well things are slow here so dug out the HP manuals for the AB and CB The earliest is a 400B tubes 6J7 6F6 6F5 6V6 and 5Y3 Wein bridge with lamp bulb regulator 400 VDC not available in 1960 The AB has 6SJ7 6K6 6SN7 2 6K6 PP and a 5Y3 250 VDC Rated 1 watt into 600 ohms 25 VRMS range 20 to 40 000 CPS 1 distortion 30 to 20K Cabinet and rack mounting good for measuring speaker impedance without an additional amplifier price 120 in 1960 The CD has a balanced Wein bridge and amplifier tubes 2 6SH7 2 6AU5 and a 5AR4 190 V
508. rned with The best thing to do right now is to identify whom made each of the receivers and let us as a collective know what you have Having that information the collective list knowledge can be brought out to give you the best plan for the endeavor that you are about to start upon This is not meant to put you off It is a necessary part of what is needed to know before anyone on the list can begin to give you GOOD advice test gear page 391 Date Tue 6 Mar 2012 18 35 58 0600 CST From nryan mchsi com Subject Re R 390 Capacitor tester like my Sprague Tel Ohmike Capacitor Analyzer model TO 6A I m sure there are others that you ll hear about from the list but you can t go wrong with the Sprague Who knows maybe your luck will continue and you ll score a nice unit somewhere Otherwise have fun with your new acquisitions Date Tue 6 Mar 2012 18 42 40 0600 From Don Cunningham lt donc martineer net gt Subject Re R 390 Docs First Bob thanks for what you are doing It helps to have the docs available at one site instead of people having to send them separately only wish had some space to offer but that s not part of my ISP s service unless extra is paid hi Side issue would anyone have the documentation for the LogiMetrics 925 S125 signal generator see on searching the web some manual copies for sale even found one original pretty pricey but was wondering if anyone here might have the docs in p
509. robe as 3 dB bandwidths Makes a significant difference say Tek probes are tender because they are abusable The coax is made with foam dielectric and a hair wire center conductor to minimize capacitance The cable is not available anywhere that I ve found The center conductor is nichrome or stainless steel and is nearly impossible to solder so is crimped but have fixed a probe or two Its not so pretty but works One new probe with my Tek 475 was intermittent for 15 years or so until cut off a strain relief and fixed up a faulty braid connection I m not much of a fan of switchable probes that switch at the matching box on the scope end of the cable They have the cable C in circuit in the attenuated position and it significantly detunes RF and IF tuned circuits Given a choice of surplus P6006 and something aftermarket I ll take the Tek probe Date Fri 26 May 2000 14 27 14 0500 From Dr Gerald N Johnson lt geraldj ames net gt Subject Re R 390 probes Some Tek numeric series history as remember it could dig into my collection of Tek and Tucker catalogs and refine it to dates but it begins in the 1950s In the beginning Tek made the 50x one piece scopes no plug ins Then they made the 51X with a few MHz bandwidth Then the 53x and 54x as large with vertical plug ins began with letter series then went to 1Xn later Some in the series could take two vertical and a test gear page 10 horizontal plug in The 53x
510. rolytic Thanks for any comments and or suggestions Date Sat 9 Jul 2005 13 45 59 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 R 390A test equipment Yeah the rectangular caps on the printed circuit board should all be suspect especially if they are covered with goo Date Sat 9 Jul 2005 23 34 56 EDT From Flowertime01 wmconnect com Subject Re R 390 R 390A test equipment test gear page 355 Have you taken the time to check all the tubes Since day one those fire bottles have been problem one that has keep many a tech busy Then check those caps The power draw on the URM 25 is not big and the paper caps were good enough Space in that box is tight and may have been a reason for the paper Test equipment bounced around from bench to bench The paper caps may have offered a higher G force rating and been considered less likely to fall apart Date Fri 19 Aug 2005 08 57 50 0400 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 Hollow State News gt Here s Ralph s current email address gt r sanserino worldnet att net gt Contact him for available reprints While you are at it find out if Ralph can still supply copies of URM 25D Overhaul Notes by Dallas Lankford 11 88 revised 1 94 with copy of HSN Supplement from Issue 41 about the Terminal Board The Overhaul Notes themselves did not appear in HSN only a notice that they were available separately There are
511. rowse function on the web site It s all very frustrating From Laird Tom N lt LairdThomasN JohnDeere com gt Date Fri 9 May 2003 10 50 32 0500 Subject R 390 RE CHEAP DVM 2 99 It is Cen Tech Item number 30756 4VGA Date Fri 09 May 2003 11 10 20 0500 From Tom Norris lt cthulhu fhtagn org gt Subject R 390 Comment on the CenTech DMMs bought one and took it to work with me to the cal lab and put it on the Fluke 5720 calibrator The darned thing is pretty accurate say get one for each tool box at that price and a couple for spares if they are all that good Have bought other models as gifts off the E place and they seem to check out as well Can t vouch for the durability or how well they will stay in cal in the long run but for ham and home use and for the price it s a bargain You want a super hand held meter then buy a Fluke model 89 or something An affordable rugged meter get a Fluke model 12 under 100 usually but a decent knocking around meter get a couple of these From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 RE CHEAP DVM 2 99 Date Fri 9 May 2003 11 14 54 0500 Looks like all us hams looking for cheeepie DVMs have brought HF s server to its knees From Buzz lt buzz softcom net gt Subject Re R 390 RE CHEAP DVM 2 99 Date Fri 09 May 2003 11 09 47 0700 test gear page 83 I ve had one of these meters for a few years and after a few months o
512. rrent convention back then Date Fri 22 May 2009 09 29 28 0400 From Barry lt n4buq knology net gt Subject Re R 390 Filter caps lt snip gt On a side note had a very fun evening last night finally managed to get the HP606A on the workbench and started checking it out The dial plate was way off from where it should be something like 10 to 15 degrees and figured out that removing the big tuning knob revealed four screws that clamp the dial plate to the collar eye balled the dial to have about the same amount of over travel on both ends of the hairline and tightened the screws The range change knob was incredibly hard to turn and found that was mostly due to hardened lubricant on the shaft itself disassembled it cleaned and relubed it and the range test gear page 195 switch is much easier to rotate now was figuring it was something much deeper in the mechanism and was surprised to find the dried lube could make that small shaft so difficult to turn When started checking out the calibration it was almost spot on on all but the top range must have gotten very lucky when clamped the dial plate back in place One range needed a slight tweak on the upper end and all but the top range didn t really need anything done There isn t enough L or C to bring the top range into calibration though I m not sure what can do about that suspect something not on the oscillator turret that s not off enough to effect
513. rrent is flowing through the 100K resistor however if measure the before and after voltage from B to the screen grid would see a difference there too Date Mon 8 Jun 2009 12 58 16 0700 From David Wise lt David_Wise Phoenix com gt Subject Re R 390 OT just a bit From whence cometh the grid current test gear page 201 Voltage dividers present to their load an impedance equal to the top and bottom in parallel See http en wikipedia org wiki Th C3 A9venin 27s_ theorem Date Mon 8 Jun 2009 16 24 06 0400 From Al Parker lt anchor ec rr com gt Subject Re R 390 OT just a bit From whence cometh the grid current and the screen grid does draw current more significantly than a control grid might Date Mon 8 Jun 2009 18 40 01 EDT From Flowertime01 wmconnect com Subject Re R 390 OT just a bit From whence cometh the grid current Screen grids are positive and there fore must suck current out of the tube As the voltage at the junction drops with the tube in play more current must be going through the top resistor to give a large voltage drop Some current is diverted from the bottom resistor through the tube to allow the bottom resistor to drop less voltage Date Tue 9 Jun 2009 19 09 16 0400 From Steve Hobensack lt stevehobensack hotmail com gt Subject Re R 390 grid current You could have a gassy tube Date Tue 9 Jun 2009 19 03 00 0500 From Barry lt n4buq knology net gt Subj
514. rward movement From Bill Smith lt billsmith ispwest com gt Subject Re R 390 Meter Meister Date Mon 16 Jun 2003 20 54 48 0700 Sounds to me like something is open Set an ohmmeter on a high scale then measure from outside terminal to resistor through resistor to meter then to the small terminal that holds the spring then to the other side of the meter watch meter movement here etc Test from both meter terminals The meter current passes through the springs to the wiring in the armature Have found metal to metal contact can still be an open electrical path particularly the hardware between the meter bridge and the spring test gear page 91 Sometimes just moving things around will break down oxidation Don t think that is the case with yours though You might look for a broken or disconnected spring though that would affect meter zero or open armature If you see a lot of life in the meter movement let s all hope then one of the series resistors has opened If the armature is open you might try looking under a very strong magnifying glass as in a lab microscope to insure the wire contact between the armature and spring terminal is still intact Have fixed a meter or two by reattaching a loose or broken wire end The wire size is extremely small Of course that is a very delicate operation If the armature winding is broken somewhere inside the winding that may be fini would be for me Date Tue 24 Jun 2003 09
515. s Good meter and if had a spare would offer it to Gary cheap have bought them off the E place for years and refitted them But I m only a low level Government Wage Grade employee what do know And that s the way the Government spends your tax dollars and thinks folks end of economics lesson Date Sun 20 Mar 2005 15 23 21 EST From Llgpt aol com Subject Re R 390 OT Looking for TS 352 or AN URM 105 or 10000hm v tester The 9 volter s last looooonger test gear page 116 Date Sun 20 Mar 2005 14 19 43 0800 From Ed Zeranski lt ezeran ezeran cnc net gt Subject Re R 390 OT Looking for TS 352 or AN URM 105 or 10000hm v tester still have a 352 to go with contemorary Navy radios as well as the PSM 4 that replaced it think the 4 5Vdc batteries are BA 31 and the pin jacks are less trouble than a wafer switch in the nasty shipboard environment and probably cheaper too Date Mon 21 Mar 2005 23 58 11 EST From Flowertime01 wmconnect com Subject R 390 TS352 Meter Yes that was the meter with all the pin jacks We used them on the bench and dragged them out to the bays We liked them better than the 505 because you did not need to plug them into the AC line The real problem with them was the probe tips You forgot what you were doing and pulled the meter over Likely as not you would break the pin off at the meter Both ends of the test lead used the same probe tip also the same pin tip as used on
516. s etc gt Ferrite beads here are just palliative that s mostly ineffective A few gt ohms maybe 50 series reactance where thousands are needed OK no ferrite beads then They do look cool though gt A low loss adapter to use a 5763 in place of the 6AG7 might be of benefit The oscillator in my Q meter uses a 5763 test gear page 321 Date Sat 16 Dec 2000 12 59 55 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 URM 25 Stability You need contact close doesn t count A slot radiates according to its length not its width or depth braid around an o ring in a slot seems to be more predictable My Q meter uses a 5763 had to figure it out when bought it from the circuit connections because it was missing got the manual later Date Sun 17 Dec 2000 13 17 17 0800 PST From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 URM 25 Stability Cured Update Warmed up for 12 hours case has no cool spots evenly warm output reading solid as a rock After 24 hours same thing Conclusion Needs I o n g warm up time to get EVERYTHING warm and stable Date Tue 19 Dec 2000 21 19 27 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 URM 25 Stability Ferrite beads function as RF 50 ohm resistors from HF through microwave not a lot of series impedance but relatively independent of frequency RF chokes b
517. s including its own without an adaptor that they were forced to revive the older model Date Sun 03 Oct 1999 14 38 51 0400 From Wm L Townsend lt wit tesnet com gt Subject Re R 390 Yeah just got me a URM 25 D think you ll find the URM 25D to be pretty nice think it s hard to beat for the price The only problem is you will need some serious biceps if you change bands a lot One thing that s worth checking though is a couple of coupling capacitors In particular C135 and C136 These are in series between plate of the 6AG7 output buffer and R130 which feeds the attenuator The B to the 6AG7 is about 220v so if these capacitors leak much you can get lots of current through R130 499 ohms and the attenuator This is similar to the effect you get in an R390A when C553 shorts except you get a whole lot more smoke with a URM 25D C136 gets shorted by the switch to the left of the meter when you re in the 10 300kc position so in that case all that s between B and the attenuator is C135 and R130 My generator had a shorted C135 Everything was fine had used the generator for probably a year with no problems One day set the switch to the 10 300kc test gear page 269 position It made a nice smell as R130 went up in smoke Fortunately R130 went open and saved the attenuator You can check for shorts in these capacitors by looking at the dc voltage coming out of the RF Output BNC Set the attenuator to X10K Al
518. s together test gear page 41 2 Loosen R6 and adjust it for center scale reading 3 Lock R6 and verify meter reading AC ZERO DEFLECTION 1 Turn FUNCTION to AC 2 Short AC and COMMON together 3 Loosen R45 and adjust it for zero reading on meter 4 Tighten R45 and verify meter reading AC FULL SCALE DEFLECTION 1 Turn RANGE to 5V Rx10 2 Loosen R12 and apply 5 VAC 60 Hz or 1 across AC and COMMON probes 3 Adjust R12 for full deflection 4 Lock R12 and verify meter reading before disconnecting AC source That s it There is no calibration for the OHMS function Closing thoughts As with all vintage gear replace the power cord with a three wire grounded ran into trouble calibrating my TS 505B U to full scale deflection Tubes already had been tested Next checked the carbon comp resistors R19 82K was way high and replacement of it plus a few others in the area that were out of spec made it possible to calibrate to full scale Typically these rugged and well sealed units are very clean inside and fun to work on Check condition of the probe wires and see if there is still a 220 Ohm precision resistor inside the AC probe handle on the TS 505 A and some B models The C and D models require no resistor inside the handle Date Tue 19 Dec 2000 08 19 29 0400 From Jeff Adams lt jadams mcqassociates com gt Subject Re R 390 TS 505 Electronic Multimeters have a scanned manual on one of thos
519. s a voltmeter Regards to everyone and keep the posts coming Date Tue 26 Jun 2007 11 13 41 0400 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 Tube testers wonder if the RCA designed RBB and RBC receivers had the same kind of specification and performance They use the octal 6SK7 and 6AB7 tubes or the military equivalents VT 117 and VT 176 respectively Bernie s experience with telephony equipment may have involved Western Electric tubes These are legendary for long life and satisfactory service with low electrode voltages especially filament voltage A very special application was in telephone repeater amplifiers that were enclosed in undersea cables and put on the bottom of the Atlantic Ocean and other oceans no doubt and expected to work for a very long time want to run my RAL and RAK TRF receivers with WE tubes but have not yet found a more affordable source for the WE type 336A the 10 volt filament equivalent of the type 41 AES sells them for about 20 each test gear page 150 Date Tue 26 Jun 2007 11 36 14 0400 From Barry Hauser lt barry hausernet com gt Subject Re R 390 Tube testers dunno Bernie as with anything there are other considerations those manuals were written when the gear was new and assumed it was within a few years old There are words in most of the old manuals that are there to avoid the wasteful tendencies of some tube jockeys Some of it was there to sav
520. s is more a convenience for building from a casting than planning on the mass for thermal control The shielding is absolutely necessary for hiding the oscillator running a watt or two of power from a receiver wanting to see something less than 120 dbm It takes a lot of attention to details to keep the leakage down that low Its even harder to get the leakage down below 145 dbm Even starting with a 1 milliwatt oscillator Date Fri 15 Dec 2000 14 22 02 0800 From Ed Zeranski lt ezeran concentric net gt Subject RE R 390 URM 25 Stability My backup sig gen is a 25F There were some switch problems and a loss of mod but it has been fine since the fix do let it cook over night before using it though Date Fri 15 Dec 2000 17 30 10 EST From Llgpt aol com Subject Re R 390 URM 25 Stability That s a very sensible idea have always left the R 390A SP 600 s etc warm up overnight before alignment Date Fri 15 Dec 2000 16 07 48 0800 PST From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 URM 25 Stability didn t mean that the mass was for thermal control what was considering is that since its there it has to reach thermal equilibrium in order for the generator to be stable That should take a lot longer than on a cheaper commercial unit Do you have any suggestions to reduce the leakage on an old URM 25 Any suggestions for optimizing stability Date Fri 15 Dec 2000 19 33 55 EST From Llgpt ao
521. s on usually where the strain relief on the cable joins the gray plastic of the probe body Most of the new probes should work they will usually be BNC connectors You should watch for the max DC voltage rating as you will be using them for higher voltages with boatanchors stuff A probe with a X1 X10 switch would be useful as the older test gear page 9 scopes have limited sensitivity and where the capacitance loading is not important you can use the X1 setting and get higher sensitivity Date Fri 26 May 2000 10 19 04 0500 From Dr Gerald N Johnson lt geraldj ames net gt Subject Re R 390 probes The selenium rectifiers will need replacing if they haven t been already The P6006 probe is decent though tender The tip ground is from a ground wire that clips around the probe at the front of the strain relief They come in various lengths Last looked Tek sold such accessory kits for a reasonable price The kit includes pinchers and various lengths of ground wires When shopping for probes with attenuation and in a BA there s rarely a need for a direct probe which can be a piece of RG 59 though it will have more capacitance than a Tek probe its important that the scope input R and C are in the range that the probe can match Tek probes are the best though could cost more new than the used price of the 543 Tek rates scope and probe bandwidths as the frequency flat while some other and more economical makers rate scope and p
522. s only a few hundred centimeters per millisecond about 3 orders of magnitude slower than later small scopes like the 464 Also the contrast and brightness of the stored trace is low and the storage mode tends to be a bit finicky to set up for a good clean capture There was a variable persistence option available on some of the 564Bs which is useful when viewing repetitive signals at a low sweep speed like 50ms to 1s per division One unusual feature of the 564 storage tube was that the upper and lower halves of the screen had independent controls for storage and real time display This capability made the 564 ideal for storing a reference trace on the top half and comparing it to other traces displayed on the bottom half think the 564 is a good but limited bandwidth scope when not used in storage mode The storage mode works but it is crude compared to later scopes and can t capture risetimes faster than a few microseconds or sine waves faster than a few hundred kilohertz It is relatively small and light for a vacuum tube scope and sampling plug ins 381 and 3T1 are also available that will let you view repetitive signals into the gigahertz region If you can find the 3S7 and 317 plug ins you can have time domain reflectometry capability as well But list members who might be shopping for a scope should keep in mind that the later 46x scopes offer vastly better general performance at prices not dramatically higher than a 56x mainframe
523. s stuff for years and being a big time pack rat never throw ANYTHING away But am running out of room have aligned many a receiver with my URM 25D It s in semi retirement at this time My 606A gets most of the work on one bench have a storage building 1 2 full test gear page 187 of 608 s bought a pretty nice 8640B off of ePay last year While repairing the fine tuning noticed had some cracked gears One poster mentioned metal gears Anyone have an idea where they might be purchased Date Tue 17 Feb 2009 01 02 26 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 8640B gear question Another list member asked me the same question off line and I m trying to find the source for the brass gear As far as know the seller made only the large gear in brass because it is the only one large enough to shrink enough to cause skipping but could be wrong l Il post the information when find it but if anybody else knows please feel free to do so Heck if there s enough demand perhaps I ll tool up to make some Anybody have an 8640B gear set to use as a model Not enthused about tearing mine apart if can find one that is already apart and doesn t need to go back together Best regards Don Date Tue 17 Feb 2009 08 22 53 0800 PST From Steve Toth lt stoth47 yahoo com gt Subject R 390 Question mainly on connectors I ve gotten some great feedback on test equipment from th
524. s with other equipment using GPIB if you care to It also goes down to 100 kHz The HP has a considerably greater output range 6 dB on top and 12 dB at the bottom and is better shielded so signal and hash leakage is rarely a concern Personally would probably keep one of each unless thought was going to need two generators that were better than the Fluke in the particular areas where the HP shines Date Sat 15 Jan 2011 02 00 09 0500 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 Signal Generators et al gt Sure the AN URM 25D is a pain to zero in at higher frequencies gt due to play in the gears Has anyone tried eliminating the slack The URM 25D has a single ball bearing at the rear of the tuning knob shaft If the mechanism that takes up the slack in the shaft is worn or out of adjustment pulling and pushing on the tuning knob will change the frequency The cure it to tighten up the bearing seat Be careful not to lose the bearing by loosening the thing instead of tightening it Gentle tightening of the lock nut followed by a cleaning and a spot of finger nail polish will hold the mechanism in place Do all this after a good long warmup Date Sun 16 Jan 2011 13 17 37 0500 From Barry lt n4buq knology net gt Subject R 390 HP Signal Generators In all the discussions of HP signal generators don t recall the 8660C mentioned With the correct plug ins for modulated HF work are these
525. sed the knobs are just plain flimsy Is there a place to get replacements on these Not to mention a Nicolet 1090 one of the first digital storage scopes with a bandwidth to prove it one or two mhz It wins hands down for most chrome Also a Tek 453 50mhz and finally a WO 33B which wins for cuteness hands down Of course it would be better to to have just one or maybe two better units suppose but then didn t spend it all in one time in one place Most of these cost less than a good probe What gives with probes anyway know they re precision made but Ooops forgot one that RS scope probe thing with the little LCD screen on the side but you hook it up to a PC for real readings if that so Anybody ever work with one of those Date Wed 03 Jan 2001 18 56 05 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 R 390A Manuals and O Scope differ on a couple details The 45x Teks were not the quality or the performance of the 465 475 485 era And NO HP scope before the 1740 had comparable performance to any Tek scope The HP 1740 was their first decent scope All prior HP were hard to use and had tiny CRTs compared to the superior Teks The electronics labs at ISU were equipped with the 1740 because they were easier to teach engineering students to use than the Tek 465 though they could have bought either for the same price I ve a bias towards Tek scopes from using 543 a
526. seem to be going for a little more than want to pay given my limited use for one About 60 MHz is as high as need it to go but that rules out a simple function generator as 20 MHz seems to be their limit think want something better than an old TV sweep generator Date Sun 15 Feb 2009 18 45 17 0500 From David C Hallam lt dhallam rapidsys com gt Subject Re R 390 Test Equipment Tube testers are about the least useful piece of test equipment ever invented can t understand their popularity or the astronomical prices they command The only bit of truly unambiguous information you can get from a tube tester is that the filament is burned out don t think you need a tube tester to find that out was that the Orlando hamfest yesterday and was astounded at the asking prices for any kind of tube tester test gear page 185 Date Sun 15 Feb 2009 17 50 35 0600 From Tom Frobase lt tfrobase gmail com gt Subject Re R 390 test equipment question have a couple the Texscan which could never find much information for has been the old standby use a 8640 HP most of the time did have a Wavetek in the past both the Wavetek and the Texscan have scope connections which make them easy to use About 10 years ago there were a lot of sweepers on the surplus market guess that was back when we still made things in the US would vote for the Wavetek they are relatively easy to fix if they have not been molested
527. seems to apply to a lot of older tube based gear Pretty much 1 Replace the electrolytic capacitors especially the ones in the power supply 2 Replace any of the black or brown body tubular paper and foil capacitors 3 Look for any high wattage carbon comp resistors and check them Replace if they are more than 30 out of value Different pieces of gear run at different temperatures That seems to make some of them more prone to parts failure than others still claim that it is just a matter of time for some of the parts The parts listed above show up on lists for just about every piece of gear out there l m not sure what took out your choke It may have been a wear out mechanism or it could have been some kind of line transient One of the interesting failure mechanisms on a choke is a short on the output that heats the poor thing up Heat attacks the insulation on the winding Insulation breaks down next time power is applied Result is a short to ground Makes for a good argument to fuse the B lead In an R390 it makes for a good argument to be sure the B fuses we all do the B fuse mod don t we are the correct size and type would replace the tube rectifier with a pair of silicon diodes and a 47 ohm 5W resistor The rectifier tubes just aren t worth tracking down any more The same comment goes for just about any supply in any of these older pieces of gear Now for the nasty part Once you get the URM back to life you hav
528. send it to Dan Nelson in Phoenix He s a whiz at getting these sets up to snuff and he won t charge you an arm and a leg djn goodnet com He also has a huge inventory of used mostly cherry tubes that he lets go for very little Before shipping tests them himself on his well guess Believe me you won t be disappointed Date Sun 13 Feb 2000 19 33 02 0500 From Gary E Kaufman lt gkaufman bu edu gt Subject RE R 390 Wtd TV 7 info test gear page 256 have the TV7 settings book scanned into a PDF file Unfortunately the file is too large for easy transfer gt 40mb if remember correctly but it is nicely indexed and prints well sent a copy along for the unofficial R390A cdrom set so perhaps it will be included in a future release It the meantime feel free to contact me off list and can certainly arrange to get or print a copy for you Date Fri 03 Mar 2000 08 32 15 0500 From Richard A Tony Stalls lt bc348 sprintmail com gt Subject Re R 390 FS TV 7D Tube Tester Two points 1 Fifty bucks for a working TV 7 these days is a great deal Like Brian VE3UU said I d buy 10 or 20 at that price too 2 The TV 7D U was I believe the last model of the series and according to the TM 11 6625 274 12 operator s manual the differences are TV 7A U TV 7D U 1 F Range on function switch No Yes 2 Bias and Shunt Controls Engraved on dial On test set panel 3 Shorts lamp No panel marking Panel marking
529. series of manuals is available for download free at http www kg7bz com Manuals html Date Mon 07 Jun 2004 21 45 17 0400 From Bernice amp Al lt saglek videotron ca gt Subject R 390 SG 25 Purchased a SG 25 Signal Generator last weekend at a local Hamfest for 15 CDN Asking price was 20 offered 15 and he took it Should have offered10 bought it with the intentions of removing the main tuning capacitor to use in a crystal radio Fair Radio sold them at one time for this purpose The capacitor is a high quality part ideal for high performance crystal radio When opened up the unit just did not have the heart to part out such high quality piece of test equipment The generator is in good condition It operates well O P seems to be within spec for frequency and level All functions work The only problem is thatafter about 45 minutes of operation all modulation is lost Could be the paper caps will change them out have a URM 25F which had a similar problem After changing the caps the problem was still there It finally turned out to be the meter diode Found this by touching the diode lead with hot glass rod The modulation dropped out within a second or so Replaced the diode and the generator has been working for about 4 years now have number of questions about this unit 1 What is the history What are the differences if any with AN URM 25 The unit is sure nice inside Very clean but will be a problem if some caps do
530. set to external Most people checking these things out don t have a CLUE how they get used so they don t realize the switch even exists You can also have a counter standard that is not working internal efect and the counter won t work in that case either It pays to familiarize yourself with this piece own two before you buy one and LOOK at the photos to determine is the thing is set up to work right Date Sat 20 Feb 2010 13 20 10 0600 From Barry lt n4buq knology net gt Subject Re R 390 HP 8640B Question thought that seeing so many of them with that symptom it might mean that the user simply did not know much about them Many of the ads state as much I ve seen a couple of them at hamfests but haven t owned or used one yet hope to soon though Date Sat 20 Feb 2010 13 27 14 0600 From Mahlon Haunschild lt mahlonhaunschild cox net gt Subject Re R 390 HP 8640B Question test gear page 219 Any 8640B counter will display all zeroes if its input is inadvertently switched to the front panel external counter input connector this is easily overlooked I ve done it myself several times Were you thinking of something else By the way while writing this turned around to my equipment rack and switched on my two 8640Bs which hadn t turned on in a very long time at least a year The freq displays are within 005 of where left them and the PLLs lock right up as they should I ll Keep em Date Sat
531. setup for that in my rack Cleaner better attenuator Nice knobs personal preference Date Fri 19 Feb 2010 14 35 37 0500 From k2cby lt k2cby optonline net gt Subject R 390 HP 8640B Question OT had the same problem with an 8640B a few of years ago With a bit of light machine work it is possible to adapt a couple of commercially available brass gears so that they will replace the broken delrin gear Alternatively if the original gear isn t too badly broken you can ream it out so that it again fits around the brass hub and cement it to the hub with slow drying not 5 Minute 2 part epoxy will try to gather my notes over the next few days and forward copies to anyone who e mails me with a request Miles K2CBY Date Fri 19 Feb 2010 17 35 41 0500 test gear page 216 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 HP 8640B Question The 8656A B and 8657B are great generators but like all synthesized generators their phase noise and spectral purity are orders of magnitude worse than the 8640B harmonics specified at only gt 30 dB down That s why the 8640B is beloved by engineers the world over stability similar to a synthesizer but still today world class signal purity from that wonderful cavity resonator Best regards Don Date Fri 19 Feb 2010 19 05 10 0600 From Jerry K lt w5kp hughes net gt Subject Re R 390 HP 8640B Question True as long as they re still working Hard to be
532. simplicity of operation is very valuable Maybe we can divide all of us into two groups Those who work at home at a bench or workshop and those who go some where to work on someone else s equipment and may get paid to do it Keep in mind which type you are A piece of test gear does NOT need to be portable if you never take it anywhere The GR type 1310 audio oscillator is one of my favorites It has just three controls Frequency range frequency set with big easy to read dial and a vernier knob and output level What more do you need Date Mon 23 Feb 2009 15 31 44 0600 From Barry lt n4buq knology net gt Subject R 390 HP 606A Well as much as l m trying to keep from collecting radio related stuff won an HP 606A today Any advice on this one Date Mon 23 Feb 2009 20 56 51 0500 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 HP 606A Yes here are some random suggestions 0 Find a good place for it on your bench and leave it there test gear page 190 1 Put the 12B4 s used in the power supply on your want list 2 Do a good mechanical overhaul lubrication The mechanicals of that thing are one of it s strong points You won t realize what a gem this thing can be till the tuning and output attenuator are working like new 3 Do start looking for an 8708A This gadget allows precision and stable setting of the frequency However you need the B version of the oscillator to use it So star
533. since I m not positive the Fluke is dead on it either but it agreed with the scope 0 707 p p 2 and HP was reading a bit less Date Wed 18 Apr 2001 12 48 04 0700 PDT From John Kolb lt jlkolo cts com gt Subject Re R 390 HP410B question The 410 uses a half wave diode in the probe so is average reading with RMS meter markings On a low disortion sine wave if properly calibrated it should read the correct RMS value Date Wed 20 Jun 2001 21 22 34 0400 From Bob Camp lt bob cq nu gt Subject Re R 390 Thanks and Restoration Update You might consider some of the HP or GR RF generators from the same era The HP 606 seems to sell for less than the AN URM 25 As far as can tell test gear page 53 there is nothing special about a URM 25 that makes it any better for setting up an R 390 than any other signal generator know it s totally out of touch to say this but used to set them up using the calibrator and off the air signals You can get things close enough with the calibrator to be able to hear things You can then use the local or not so local AM stations to do most of the IF stuff The RF at least through 16 MHz can be set up on thermal antenna noise if you are patient The result isn t anything to write home about but it will get the radio on the air Date Wed 20 Jun 2001 21 40 12 0400 From Kim Mackey lt mackeyka mac com gt Subject Re R 390 Thanks and Restoration Update It s nice to kno
534. sing the external reference Of course it takes week for the frequency reference to get down to the part per billion stability and you can never turn the thing off it is on a battery string to keep it going during power outages do a lot of microwave and VHF UHF design professionally and work out of my home lab coincidentally my radio room so the test equipment all supports that role Sigh maybe someday can get a vector impedance meter and a HP 8350B if win the lottery Of course IF won the lottery the lab would be more for fun than work By that time if anyone mentioned QAM anything would run screaming from the room Date Fri 13 Feb 2009 15 42 53 0500 From rbethman lt rbethman comcast net gt Subject R 390 test equipment actually find my AN URM 25D to STILL be effective It warmed up for a few hours had a high stability HP counter in line AND for three days it was rock solid The only thing I ve had to do with it from a maintenance standpoint in the recent past was to remove the power cord trim it back and re attach it It developed a quirk that IF the cord was run to the left got no power IF the cord was run to the Right power was had follow the NAVSHIPS manual for it Perform the zero per manual and calibrate Checks against WWV also When have to I ll replace it Don t have a NEED to as of yet It sure beats the OLD GR 1001A lt LOL gt The VTVM is a TS 505D U test gear page 180 Date Fri
535. sitive grid voltage or excess plate current and near zero grid voltage or by using a grid emission tube checker don t think can say that I d use microphonics as a symptom of grid emission I d want to replace the microphonic tube to prevent microphonics from getting into feedback from the speaker and transformer vibration anyway And I d want to replace the tube with grid emission because it upsets the AGC which leads to distortion and burned fingers when preparing to pull the hot tube for testing because of the high plate current And every time it happens to a 6BAG in the IF of my 75S3B it makes the S meter pin backwards Date Mon 24 Jan 2000 14 34 55 0600 From Nolan Lee lt nlee gs verio net gt Subject R 390 Re Tube Testers don t have any real experience with commercial tube testers Other than for CRT testers all of the testers I ve owned were military ones guess that if could only have one tube tester I d have to go for the TV 7D It seems to have been about the most common military tester made and one of the easier ones test gear page 250 to track down parts for if you need them The calibration procedure isn t difficult if it s a D model and they re pretty reliable Replacing some parts in them is a pain in the ass they re pretty compact I ve been using one of mine for 25 years I ve worn a lot of paint off of the front panel and it s ugly as hell but it works like a champ Also the TV 7 series has probably
536. sive but for the difference in the labor who would really care gt Mine is SG 103 URM25F NObsr 59613 number 3369 CCBZ That s the contract Good old New London Instrument Company gt have a repro manual TM11 555IE Sept 1956 Interesting that s over a year later than the Navy manuals The supplement may or may not apply to your manual It ll be easy enough to check by comparing the parts list and schematics By any chance is the 25E model described in the Basic Differences table toward the front of the manual gt Would appreciate a copy of a supplements changes to this unit as gt well if it is not too much trouble No trouble at all attached it to you several minutes ago Date Tue 25 Jan 2000 13 21 13 0500 From Mark Mohrmann lt mohrmannm mail lsc vsc edu gt Subject R 390 Re AN URM 25 Capacitor Replacement Well I m not the guy to take on that project but here s a start for someone who will Here s what came up with after receiving a couple of responses to the question of which capacitors must go in the URM 25D In addition to Dallas Lankford s notes suggestions included replacing all paper caps what about the hermetically sealed glass to metal tubular ones and test gear page 301 specifically C132 can be leaky C135 C136 known to have fried attenuators Also C131 because its easy to get to and ALL caps on the audio board because they re easy to get to Audio Subchassis C159 0 01 3
537. so set the SET CARRIER TO 10 pot fully counterclockwise when you do this This kills the oscillator and keeps you from seeing 20 30 mv you may get from from the meter rectifier if there s any RF present Start with the X Mult switch all the way clockwise There should be no dc voltage on the BNC It s unlikely that you will see any DC in this position because both capacitors would have to have failed they re in series except when C136 gets shorted in the 10 300kc position Assuming that s OK if you rotate the switch counterclockwise there should still be no voltage in any position If you see DC in any position either move the switch to a position where there s no DC or turn the generator off REAL QUICK It takes a few seconds to really roast R130 and by the time you can smell it the damage is already done DC when in the 10 300kc position indicates a bad C135 This test won t really check C136 unless C135 is also bad since the two are in series If you need to replace C135 plan on spending a few hours it s a real pain to disassemble the generator enough to get at it I m not sure whether this is a common problem with the URM 25D I ve never heard anyone else mention it but it s easy to check Date Sun 3 Oct 1999 16 40 07 0700 PDT From Joe Foley lt redmenaced yahoo com gt Subject Re R 390 Yeah just got me a URM 25 D gt gt suspect a problem with the attenuator only get a good output on the X10K and X1K set
538. ssible to find gt Or a pair of long thin hemostats with a couple of flats ground gt into the serrations to put the lockwashers and nuts in place gt Been there done that Several times lt grin gt gt nolan test gear page 254 will make those the next time have to open it up found some paperwork and a spare knob inside when did Thanks for the info By the way your I 177B database is purely awesome use only that now and it is truely a thing of art Wish remember the guy who wanted to charge 5 per tube to figure out the settings for the I 177 but changing computers a few times and moving 3 times contributed to losing addresses and notes on things Date Sun 13 Feb 2000 17 18 54 0500 From km1h juno com Subject R 390 Wtd TV 7 info A TV 7A U followed me home now need to know how to care and feed it Used these things for more years than will admit to in the Navy but haven t used one in many years Belonged to another Ex Navy ET friend who runs a 2 way radio shop and has finally decided he is no longer doing tube radios Contract 25006 PH 54 Serial 5447SLE Im guessing that is a Philly Navy Yard or Philco 1954 contract Has the manual adaptors pin straighteners in the cover and some addemum sheeets Worked when turned it on but what should really do to this before getting some serious use Sorta remember some TV 7 threads here but out of sight out of mind Latest chart info Date Sun 13 Feb 2
539. st as gt well have all of the HSN in a 22mb zip file on my mediafire account gt You should be able to get it here gt http www mediafire com 0ljgwit 9fhlowno If there is enough interest I ll host them on my site have an index through issue 45 it says the URM 25D rebuild article was in HSN 39 page 6 There are other references to the URM 25 General 21 4 amp 5 31 3 32 8 41 7 Modulation oscillator problems 34 6 Repair case history 38 6 Date Tue 06 Mar 2012 11 37 30 0500 From David C Hallam lt dhallam knology net gt Subject Re R 390 AN URM 25D Repair Info More The Dallas Lankford information used to be available at this site http www kongsfjord no di dl htm but it doesn t seem to be active anymore Too bad there was valuable information there Maybe someone knows if it has moved elsewhere test gear page 388 Date Tue 06 Mar 2012 11 53 38 0500 From rbethman lt rbethman comcast net gt Subject R 390 AN URM 25D Repair Info Dallas Lankford Maintenance notes have the Dallas Lankford Maintenance notes in PDF form l Il put them on MY site today lt snip gt Date Tue 6 Mar 2012 12 01 12 0500 From Nick England lt navy radio gmail com gt Subject Re R 390 AN URM 25D Repair Info More The Wayback Machine is your friend grab em while you can http web archive org web 20101124124237 http kongsfjord no dl dl htm Date Tue 06 Mar 2012 12 35 16 0500 From rbethman
540. st gear page 67 gt they are odd and expensive think Check this with someone who knows for gt sure Roy From JM CO lt jmerritt2 capecod net gt Subject Re R 390 Audio Signal Generator question Date Thu 29 Aug 2002 13 34 03 0400 The CD has a balanced 600 ohm output The A does not VERY late versions of the CD were also very low distortion This series of HP generators was manufactured for decades and were very stable and reliable Suggest that you obtain the correct service owners manual Make sure that the manual that you get matches the serial number of your unit as there were many mods made over the production lifetime of these units Chuck N1LNH From Scott Barry Clyde B lt cbscott ingr com gt Date Thu 29 Aug 2002 13 42 44 0500 Subject R 390 Printing DjVu files was Audio Signal Generator question Does anyone know of a problem printing DjVu files downloaded the HP200AB manual from BAMA but it is in DjVu format downloaded the viewer and can see it just fine but if Print Preview or Print get a blank page Is there a setup missed From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 Printing DjVu files was Audio Signal Generator question Date Thu 29 Aug 2002 16 24 47 0500 Well if all else fails SHOULD HAVE READ THE DOCUMENTATION found that one isn t supposed to use the File gt Print facility from the browser Instead one must use the p
541. st has one of these or has ever seen one please let me gt know if my suppostion is correct No do not wish to purchase one gt However this may be a very useful item so included it with this posting gt gt did not know until a few years ago that another company made a specialized gt version of the 11042A coupler described above At a hamfest found an RCA gt Type CP T75N coupler Part 1044899 50 It is an exact duplicate in body of the gt H P coupler BUT with 2 important differences gt gt 1 It is for 75 ohm system use and is equipped with Type N 75 ohm gt connectors which are NOT inter mateable with 50 ohm Type N gt gt 2 It has a different value of special capacitor for the probe to contact gt when inserted gt gt suspect that this special probe was made for radar applications as it gt was made by RCA Canada Limited It might have also been used in gt television systems but am not sure RCA did a lot of radar work back gt several decades ago gt test gear page 200 The HP archive site has a catalog that lists the 455a You can get that catalog at lt www hparchive com Catalogs Specialized HP Catalog 195x UHF equipment pdf gt But as you found in other places it does not tell much about the insides Date Mon 1 Jun 2009 09 30 42 0400 From Barry lt n4buq knology net gt Subject Re R 390 HP 11042A Thanks for the info Roy wondered how the probe co
542. st thing for evaluating performance of a handful of tubes once they have passed the gas and shorts test there is still a purpose for a decent tube tester That said check caps and resistors on the appropriate testers prior to placing them in the circuit too and they are all new components Just a peace of mind thing guess Also commercial radio shops were run on a shoestring too Had a friend that owned one there was no money to be made in that business most of the test gear was really old as was the vehicles they ran around in My shop is equipped better than most Motorola or GE service shops I ve been in Date Tue 17 Sep 2013 17 00 43 0700 PDT From R David Eagle lt kb8nnu yahoo com gt Subject Re R 390 Tube Testers Thanks to all that replied guess never realized the 390a as a good tube tester hi hi But now have tube extenders on my shopping list of items to find so can have test points to go off of Date Tue 17 Sep 2013 20 26 10 0700 PDT From wli lt wli98122 yahoo com gt Subject Re R 390 tube tester picked up an 177 years ago and it has been useful to quickly check a bunch of newly acquired tubes think that tube testers are good at screening for internal shorts or open heaters and not much else As others have stressed the one meaningful test of any specific tube is its performance in a real circuit After all that is the one place where you want it to function Roger h
543. sters have an HF sig gen for sale an ex military SG 1144 U This is a solid state general purpose 50 KHz 80 MHz unit with a metered and leveled output range of 127 dbm to 10 dbm in five freq bands Puts out CW AM 400 or 1000 and FM 0 75 KHz deviation FM modulation available above 28 MHz only Red LED 4 digit freq counter built in Built in the early 80 s believe this was the general purpose sig gen that replaced the AN URM 25 x series have used it on my bench and it is very stable after warmup and works just fine on all ranges and modes Modulation deviation and percentages were checked against my Racal 9008 mod meter and were very accurate The output attenuator was tested against a lab grade millivoltmeter down to 50 dbm as low as could test it and is also very accurate Standard operating method is to T the output to a real freq counter use the sig gen s 4 digit LED freq counter to get in the ball park then tweak the freq fine tune to home in About 16 x 17 x 7 31 pounds Front panel is very good case is decent with a beige repaint job over the military grey a few chips in the paint 80 plus shipping will buy it and although can t guarantee NIST calibration will certainly guarantee it all works as advertised A couple of digital photos are available to email if somebody wants to see it 73 Jerry W5KP Mustang OK Date Sun 19 Jan 2003 14 27 24 0600 From r390a enteract com Subject Re R 390 For S
544. stevehobensack hotmail com gt Subject Re R 390 ME 26D U Date Sun 18 May 2003 08 25 04 0400 The probes should be interchangeable but think there might be 1 volt difference in the filament voltage As remember the plastic head was difficult to unscrew from the body but it does dismantle The input cap is a disk ceramic without a coating and it is easy to burn out by putting more than 300 volts AC across it put a miniature toggle switch on the meter front plate to turn off the probe filament when use the meter for ohms or DC Date Wed 4 Jun 2003 06 48 19 0500 From Dave Merrill lt r390a rcn com gt Subject Re R 390 Fuse lamp in TV 7 Tube tester test gear page 86 gt My Fuse lamp is blown In the TV 7 manual it says it is a type 81 the lamp gt have is a type 83 on the side of the lamp probably why it has blown gt Any one know of a source What are the specs on this lamp Volts Amps 2222 gt live in Australia don t have a source here Could some one ship me a couple gt and will reimburse them please The 81 is a 6 5V 1 02A lamp originally for auto service when US cars were 6 volts Here is a supplier who ships worldwide http www vacuumtubesinc com index html From Bill Smith lt billsmith ispwest com gt Subject Re R 390 Meter Meister Date Sun 15 Jun 2003 00 29 27 0700 gt need someone to tell me what just did to ruin this DC voltmeter You probably didn t do an
545. stiff to avoid it moving after you set it but I m just curios Mine works great Ben KJ4CC Date Mon 10 Jan 2011 13 45 05 0800 PST From Mack Rogers lt n4vgb yahoo com gt Subject Re R 390 8640B Both mine are firm but not really what I d call stiff presume it would also depend on how well used each one might be bought both mine from a surplus dealer with a good reputation and a very good bench tech test gear page 233 Date Mon 10 Jan 2011 16 53 51 0500 From Jon Schlegel lt ews265 rochester rr com gt Subject Re R 390 8640B Of the two that have one tunes smooth and the other tunes somewhat stiff The one that tunes stiff works just fine as does yours had to do some other repair work on this unit but left the cavity alone think HP claimed that the cavity oscillator inside these units was very much off limits even to their repair depots The cavity oscillator in these units is what really makes these things tick so if it s working for you leave it Date Mon 10 Jan 2011 16 47 11 0600 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 8640B keep the 606 for the 50Kc IF s in some of the early tube receivers from Hallicrafters and Hammarlund The 8640B doesn t go down that far on the RF side The 606 does that work well Date Mon 10 Jan 2011 20 37 40 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 8640B gt You can also use it s internal counter for
546. t Subject Re R 390 HP 8640B Question test gear page 215 Gotta chime in with Jerry on that My 8656B came about when analog cellphone factories had to re tool and suspect there are many off lease and available now that everything has gone digital Simply put they are fantastic I ve cross checked the attenuated RF output and find it s dead on and there s nothing like being able to generate whatever frequency you want at any amplitude up to 1 volt with AM or FM modulation in 1 increments and know it s exactly what it s supposed to be 100khz through 990 mhz Another nice plus is the protection circuitry on the RF output which works very well don t ask how know this Manual some have knocked the purity of the output but I ve never found it to be an issue for what use an RF generator for And the 8640 it replaced also was properly recycled swapped it for another R 390A Date Fri 19 Feb 2010 08 33 05 0800 PST From Michael OBrien lt mikobrien yahoo com gt Subject Re R 390 HP 8640B Question How does the Fluke 6060A AN compare to the HP 8656B have one calibrated 2008 and 2 8640B s One of them was bought off ebay from a guy who does a lot of work on them Now am a little nervous about them Date Fri 19 Feb 2010 16 56 47 0000 UTC From r tetrault comcast net Subject Re R 390 HP 8640B Question Would gladly swap my Fluke 6060 for an 8640B even though the Fluke is fully GPIB d and is actually
547. t Subject Re R 390 HP spectrum analyzer question For that sort of thing my favorite is the 3585A or B Get an A B s are still unnecessarily expensive and don t perform any better You can not only look at the radio s IF you can hook it to your antenna and watch whole bands or more at once Frankly with the abysmal content on the bands these days broadcast ham everything get a lot more pleasure from watching the bands on the SA than listening to them Your first look at a local AM IBOC station will gross you out Date Fri 6 Aug 2010 02 23 20 0000 From lt kirklandb sympatico ca gt Subject Re R 390 HP spectrum analyzer question HP 8560 series is a higher end spec A compared to the 8590 series Going back both hand green phosphorous screens A common problem for both was the screen would fade die Hate to pay 500 2K for a analyzer and have the screen die Also if someone left it on too long the phosphorous would be test gear page 225 burned in would suggest making a simple one You can fashion a power detector either with a diode or go with one of the Analog Devices log power detectors ie like that used in the W7ZOI spectrum analyzer wouldn t buy one unless you can really check it out Attenuators could be shot had an older model and the nylon gears had split controlled the RBW VBW rates confess have a R amp S 28 GHz spect A that use at 500 kHz It is a 2 story unit and runs on DOS bu
548. t The guy who has them is ozregl36 aol com Date Tue 26 Oct 2004 07 15 04 0700 PDT From djmerz 3 cities com Subject Re R 390 Tube Tester Bob would be interested in the circuit of wnat you propose Not that would likely end up building it but it would be educational to see how simply it might be done There are other classes of tubes older stuff that it might be useful for as well best regards Dan Date Tue 26 Oct 2004 11 57 11 0400 From Veenstra Lester lt lester veenstra Imco com gt Subject RE R 390 Tube Tester test gear page 110 However to play devils advocate and CTM The best tube tester is the R 390 with a signal generator Date Tue 26 Oct 2004 12 51 09 0400 EDT From John Lawson lt jpl15 panix com gt Subject RE R 390 Tube Tester With the possible caveat that one needs to be very sure of the goodness state of all the other devices in the radio else a complete calibrated signal trace is required to insure that all other stages with the exception of the stage of interest are of a known on spec condition Otherwise you get into the two and three and nnn unknown variable chaos That being said using a perfect R390 for substitution testing of suspect tubes is fine again with the caveat that you can meaningfully and accurately measure the change in the system caused by the substitution and then relate that back to the Tube Under Test parameters This gets easier if the
549. t US Settings CV Chart GM Chart VT Chart Europ_Equiv Date Mon 16 Sep 2013 19 03 20 0700 PDT From R David Eagle lt kb8nnu yahoo com gt Subject R 390 Tube Testers Ok all my boat anchor enthusiasts am preparing to restore my first 390A My question to you all is what is a good universal tube tester to have around and what would might be a good price Date Tue 17 Sep 2013 02 01 13 0400 From Charles Steinmetz lt csteinmetz yandex com gt Subject Re R 390 Tube Testers Honestly there is no need for a tube tester unless you have a pile of used tubes you are going to sell and want to be able to say they test good The circuit the tubes are used in is always the best tube tester money can buy If you get some tube extenders with test points you can measure all of the tube voltages from the tube side of the chassis Date Tue 17 Sep 2013 02 13 30 0400 From Glenn Little WB4UIV lt glennmaillist bellsouth net gt Subject Re R 390 Tube Testers Your best tube tester is the instrument that you will be using the tube in If it works in the circuit it is good test gear page 409 Measure the voltages around the tube If they vary significantly from the manual replace the tube If this fixes the problem the tube was bad If the problem remains put the original tube back in and find the bad capacitor open coil or out of tolerance resistor Most of the resistors will be out of tolerance high
550. t but am very apprehensive that a gear will fail and will be in the market for a replacement also use a pair of BC 221s when am aligning receivers for band end points one set at the high end and one at the low end The BC 221 is more difficult to set on frequency but it is very stable and when properly calibrated plenty accurate enough frequency wise They are also cheap if you buy them properly One of those bought cost me 10 00 and the other one 5 00 The 10 00 one had an AC power supply in it Date Mon 22 Oct 2007 03 00 56 0400 From Richard Spargur lt k3ui comcast net gt Subject R 390 AN URM 25J have an AN URM 25J on loan from a friend to use to restore a few R 390As have am familiar with the AN URM 25C D and F models from military service starting in 1969 Does anyone have a manual or some documentation that shows what an AN URM 25J is Date Mon 22 Oct 2007 03 04 33 0400 From Richard Spargur lt k3ui comcast net gt Subject R 390 RE AN URM 25 Does anyone have an electronic copy of the manual s for the AN URM 25D F test gear page 365 and J models Date Mon 22 Oct 2007 11 43 49 0400 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 AN URM 25J It is a URM 25D apparently But Les notes that it has more attenuation stages Does yours have a label on the front panel that says URM 25J have more than normal positions on the RF output attenuator
551. t gt Issue Date for the following test equipment gt gt gt gt AN URM 25D gt gt NAVSHIPS 92134 A Instruction book for R R Signal Generator Set gt AN URM 25D gt TRAD Electronics Corp gt Asbury Park NJ gt gt contract NObsr 52725 NObsr 59494 appr by BuShips 31 Dec 53 gt contract NObsr 71121 NObsr 71304 change 3 appr 30 Sept 58 gt contract NObsr 711760 NObsr 75306 FBM change 4 appr 11 Dec 58 gt contract NObsr 75083 NObsr 75870 change 5 appr 1 Sept 59 gt gt Hope this is what you need amp is some help gt I d sure like a copy of the HSN Dallas Lankford articles covering the test gear page 130 gt AN URM 25D if some one would be kind enuf to copy amp send for costs Date Sun 12 Mar 2006 14 48 54 0600 From Barry lt n4buq knology net gt Subject R 390 Matching info wanted My signal generator s output impedence is 100hms A few years ago seem to recall a discussion we had about matching networks made up a couple resistors Knowing the input impedence for the balanced connector is supposed to be 125 ohms I m running with a mismatch Placing a 115 ohm resistor in series with the generator lets the radio see 125 ohms but then the generator is seeing 240 ohms One can place a parallel resistance across the generator so that it sees closer to 10 ohms but then that throws the 125 ohm impedence off Is there a way to construct a matching network of sorts using a r
552. t all of them but am still missing a few A list of them is on my site If you have access to any of the several that I m missing drop me a note Another six weeks or so and lt grin gt Actually if a few of you would care to spend some time proof reading it I d be happy to send you a section Say all of the Oxx or 1xx or 2xx numbered tubes For the 6xx tubes I ll break it down as 6Axx 6Bxx etc Let me know which section you d like to proof and I ll attach it to you They are in EXCEL workbook format Details for downloading a free viewer from Microsoft are on my site recently acquired another military tube tester model It s a TV 4A U built by Weston in about 1953 intend to do a file on it also as far as instructions and the data settings go as soon as the current TV 7 project is done So I m now in the information gathering stages for the TV 4 series tester think that it was originally part of the I 56 series test set So if you have a TV 4 series and or data for one I d really appreciate hearing from you Oh my site is at http www acadiacom net nlee and a mirror site is at http nome gs verio net nlee There have been recent updates to the I 177 and TV 2 series settings data files thanks nolan Date Sat 25 Nov 2000 21 42 47 0500 From Barry Hauser lt barry hausernet com gt Subject R 390 TV 7 Shorts Problem Very quiet on the R 390 front So here s something to work on Last night my TV 7D U star
553. t back up as you over dialed You had to have a feel for each generator You rolled up to where you wanted and watched the meters and dial You made two three passes at it and then tried a time or two to roll on the spot you wanted without going over If you went over then you dialed way off and rolled up again you had to decide if you wanted to roll up or down to get the frequency But you likely have excess friction in yours that keeps you from getting it where you want When you let go of the knob it wants to change frequency and you have trouble getting it to stick as you let go of the knob The mobile synthetic motor oil for a lube is in order You may have to pull lots of the mechanism apart and clean and lube every thing You may have to scrape a shaft and file a couple burs to get the guts smooth again You may have a bend in a shaft that is binding from years of shipping and moving The drum should drop firmly on the detents But as you dial the frequency the knob should be easy to turn and smooth Getting the mechanical motion of the generator silky is a lot like getting the KC change in the receiver to run nice and free Some lash adjustment is needed but mostly just to take the slop out of the mechanism Much like not over doing the springs in the split gears of the receivers Hope this gives you some help getting the mechanical adjustments in better condition Roger Al4NI Date Sun 15 Feb 2009 16 54 03 0600 From Cecil Acuff
554. t forward to operate It was shipped to the east coast from the west coast by UPS and was dead on when it got here have no experience with the Boonton 103B have used a Boonton VHF UHF generator before when doing commercial 2 way work and it worked OK There is a 103D on auction right now for less than 100 I m still like the HP stuff and a good 606 can be bought for no more than 100 most of the time Date Fri 13 Jan 2006 14 18 36 EST From DJED1 aol com Subject Re R 390 signal generators don t think the URM 25 the best choice these days given the availability of quality test gear finally traded up because realized that was trying to do testing with a piece of gear almost as old as am However keep it around because it s one of the few generators that will go to 50 KHz to align boatanchors with a 50 KHz IF Date Fri 13 Jan 2006 11 25 58 0800 From Craig C Heaton lt wd8kdg worldnet att net gt Subject RE R 390 signal generators Both the URM 25D and a HP8640B are on my test repair bench Got my 25D for 50 bucks last year it gets the job done Only thing it lacks is a frequency counter most shacks have one on hand One afternoon the 25D was recapped and a shorted tube replaced its ready for another 40 years The HP8640B has more whistle n bells built in freq counter and lock are nice You are going to pay much more for one and I ll bet you a soda it isn t working 100 Parts can be still found by sear
555. t looking for a nice B If you have an A and a B then you can build a signal combiner and do intermodulation tests on receivers 4 Replace the filter caps and run the generator often It likes to be used 5 One of my collected emails on the thing talks about poor long term frequency calibration stability Possibly from the ceramic forms used in the oscillator tank circuit So leave the thing on all the time 6 Stand by for a copy of my notes file sent separately A few interesting observations and discussion of the attenuator Date Tue 24 Feb 2009 08 06 11 0500 From David C Hallam lt dhallam rapidsys com gt Subject Re R 390 HP 606A would second every thing Roy has to say about the 606A amp B have a 606B with the 8708A phase lock unit It s a little fussy to get locked up but once it is it will just sit there have given up on the dial calibration and have my 5245L frequency counter also a BA connected to it have never had a problem with 12B4 in the power supply but know it is a problem in my 428B DC ammeter power supply Don t plan on moving it very often bought my 606B a few years ago at the Orlando HamCation had to drive my car into the tailgate area to haul the thing out It was in perfect operating condition until got it home It had a sticky meter but did get the particles cleaned out Due to it s weight getting the cabinet aligned with the panel to put it back together was a b h Roy if
556. t off the scale When it comes to competency the TV 10 is IMHO far more useful than a TV 7 as it does not require a chart to test a tube it can be set up using a tube manual and since is reads directly in umhos it s readings are directly useful the TV 7 series reads in 0 120 quality requiring extra work to determine an actual reading The TV 10 can also be used to beam a tube heavy current blast to blow crud off the elements and expose fresh emitter areas Date Mon 06 Aug 2012 12 44 44 0400 From Charles P Steinmetz lt charles_steinmetz lavabit com gt Subject Re R 390 Testing tubes r392 gt used to beam a tube heavy current blast to blow crud Egad What a way to destroy tube cathodes Oxide coated cathodes are not meant to have crud blown off And apart from the direct damage to the test gear page 403 cathode anything you blow off it has to settle somewhere and some will settle on the grid where it will cause grid emission which often leads to thermal runaway Thoriated tungsten filaments directly heated can sometimes be partially rejuvinated by running the filament current up a bit but with antique tubes you are much more likely to open the filament at a weak spot than to improve emission Bad bad idea Date Mon 06 Aug 2012 12 47 39 0400 From rbethman lt rbethman comcast net gt Subject Re R 390 Testing tubes r392 There are few that seek to collect
557. t was free Date Thu 5 Aug 2010 23 38 41 0400 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 HP spectrum analyzer question Cecil no doubt assumed that you want to see the spectrum near the point a receiver you have is tuned to The SoftRock thing as understand what he posted does just that though there is some confusion in my mind For lots more info Google SoftRock SDR Kit From what read the SoftRock 40 was a 40 meter receiver not meant for 455 kc and is now sold out The SoftRock 5 follow on project is now open for orders and appears to have options to accept signals in different ham bands However you may have meant to examine signals at most any HF frequency or even higher and see what the signals in that vicinity are For example the output of an SSB transmitter operating on 20 meters For this use the HP spectrum analyzers that folks have suggested will more suit the purpose look forward to more advice on the list Date Fri 6 Aug 2010 07 35 04 0400 From Shoppa Tim lt tshoppa wmata com gt Subject Re R 390 HP spectrum analyzer question It s a dessert topping AND a floor wax The issue is the HP Spectrum analyzers were not designed to be radios with spectrum displays The radios with spectrum displays were not designed to be HP Spectrum analyzers They both have similar to identical functional components and they can sometimes be pressed to do each other s jobs but they were design
558. tacting me and pointing out the correct Chicago lamp number Here s the condensed response from Ashley at Kiss Electronics We rework the lamp circuit to use modern wire lead lamps Jameco PN 41065 or whatever the current part number is Date Sun 19 Jul 2009 18 06 22 0400 From Steve Hobensack lt stevehobensack hotmail com gt Subject R 390 323 Bulb Radio Shack used to sell a sub miniature 6 volt bulb with screw base took a piece of number 20 solid hook up wire bent it around the base at the end soldered and created my own flange Some are still in my Collins 75Al receiver Should work on the 25D Date Wed 30 Sep 2009 23 20 42 0800 From Scott lt scott becklawfirm com gt Subject R 390 RURM 25D Where can download at least the operation section of a manual on the URM 25D Signal Generator Date Thu 1 Oct 2009 07 14 02 0500 From Dave Merrill lt r390a urr gmail com gt Subject Re R 390 RURM 25D You can find PDF copies of the original manuals for the URM 25 series at http bama edebris com manuals military urm25 NAVSHIPS 0967 187 5010 pdf is probably what you need Date Thu 24 Feb 2011 00 07 25 0500 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 Non A alignment question See if the IF strip is working inject 455 kc in to the in put of the IF strip from the URM Then see what frequency the PTO is really on use another receiver with a bit of wire as antenna stuck down into
559. tand the answers like how do get 1 UV out of my framitz siggen then you ll do fine with that approach too think there is enough information in the archives to do basic alignment with no siggen but an analog meter does help the VOM I ve got is too sensitive sometimes for alignment purposes use a TS 505 or a Simpson 260 Date Tue 08 Apr 2003 17 45 33 0400 From Gregory W Moore lt gwmoore moorefelines com gt Subject Re R 390 Suggested Test Equipment for R 390A Alignment Call me old fashioned if you will but can t recommend anything better than the AN URM 25 own a 1960 s vintage RCA WR 50B sig generator and a General Instrument 1310 the nomenclature number is partially obliterated on the front panel Audio generator also happen to be partial to Boatanchor test equipment for Boatanchors such as using my trusted Simpson 260 meter instead of a state of the art digital meter for measurement because in all probability that was probably used in determining the resistance and voltage figures to begin with when the manuals were first written There is such a thing as how much precision is enough and since the R 390 was originally manufactured and tested with analog equipment that is what the measurements were determined with If one were to use one s modern digital meter one can fall into tthe trap of decimal madness and take the precision way too far Basically there is no real need to look at all the d
560. tary equipment AN URM 25x stands for AN Army Navy U General Utility R Radio M Maintenance and Test Assembly 25 non specific RF Generator x which brand generator Which is about all that makes sense All joking aside the URM 25 is from a short period where someone in Procurement decided to make nomenclature a function of specification rather than a specific design You used to see a few items running around like that But the URM 25 took it to a whole new level Most of the models are completely different both electricly and mechanically You would think you were looking at completely different generators rather than minor changes in the design If the same criteria existed today the M 1 Tank would be known as the M 48C P S have a sweet mint AN BBB 3A for sale Army Navy Underwater Pigeon Bomber 3A the A stands for substituting a Duck for the Pigeon Date Fri 1 Dec 2006 13 04 09 0800 From Craig C Heaton Subject RE R 390 Differences between the various URM 25 generators I ve been meaning to reply for the past couple of days As Roger AI4NI has mentioned there were many flavors When purchased my R 390 A a URM 25D with manuals came with the deal First glance the identification plate on the front panel give the typical information SG what ever AN URM 25D The plate on the cabinet gives more information URM 25G Both list the same serial number And to add to the confusion reading the manuals
561. tary service personnel from having to make a judgement call such as How long does this need to be Date Sat 28 Oct 2000 10 13 54 0500 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 MX 1487 Adapter The labeled CG 409 U are labeled as 5 long One is made of Amphenol RG 58C U The other does not have anough maker label to tell 5 of RG 58 will have about 14 pf shunt capacitance When the series coupling capacitor is 56 pf that has a detectable effect on level at any frequency a greater effect at 32 Mhz than at 1 Mhz We are talking 20 not 20 dB 3 of RG 58 would have 87 pf shunt C and would be 1 8th wavelength at 32 MHZ in a high Z 150 ohm circuit it could cause more than a few likely a few dB difference in signal to the receiver for the same indicated signal generator output Date Wed 03 Jan 2001 12 36 01 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 R 390A Manuals and O Scope Tek 465 Maybe HP 1740 You ve never had a scope before Date Wed 3 Jan 2001 13 49 46 0500 From rbussier lexmark com Subject Re R 390 R 390A Manuals and O Scope Great subject for a new thread IMHO The Teks are very plentiful useful and best of all cheap won t mention about the whole dumpster full of mainframes and plug ins we threw away here at work And no you couldn t have anything Instant dismissal Most of the time
562. ted giving false indications on the shorts light It seems to show a short for every tube on position 5 of the shorts test I ve tested with known good tubes of the same numbers but two of the numbers at least giving the false positive are the 5814 s and the 6BK6 s haven t opened it up yet so maybe this is premature but anybody have any clues No the light doesn t come on if there s no tube under test Date Sat 25 Nov 2000 22 08 00 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 TV 7 Shorts Problem Are you sure there s not grid emission on those tubes showing up as gas Date Sat 25 Nov 2000 23 19 18 0500 From Barry Hauser lt barry hausernet com gt test gear page 258 Subject Re R 390 TV 7 Shorts Problem doubt it too many NOS tubes showing the short on position 5 of the shorts test Also had tested all of them when they came in within the last year or two and none showed shorts then Seems as though this just started up For example both 6AK6 s showed short on 5 that were in the audio deck routinely test new tubes when install them and the two new ones had on hand showed the shorts Ditto for a 5814A did have the tester idling for a long time last night Maybe something overheated Date Sat 25 Nov 2000 22 23 56 0600 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 TV 7 Shorts Problem NOS
563. ter scale moving the pointer You should be able to very gently position the meter pointer at any point on the scale without touching it If it sticks at any point there are still magnetic particles jamming the mechanism Continue cleaning with additional tape str ips 5 When the movement is free clean the inside of the glass and reassemble the meter It will work as new 6 If you did crunch a spring there are two one on the top and another on the bottom of the movement use a small pointer to very gently bend the anchor points so that the spring doesn t rub against itself at any point It should form a level symmetrical spiral about the pivot Resetting the spring is a very delicate operation that takes some experience If you are working with a valuable meter you might practice on another meter first From Steve Hobensack lt stevehobensack hotmail com gt Subject Re R 390 Meter Meister Date Sun 15 Jun 2003 11 11 57 0400 If there is no foreign matter in the meter movement one or both of the protective diodes might be shorted They are mounted in parallel but opposite in polarity across the meter terminals From Barry Hauser lt barry hausernet com gt Subject Re R 390 Meter Meister Date Sun 15 Jun 2003 11 33 27 0400 If it isn t particles or a bad protective diode it may be that the armature has come off one of its bearings or is loose Depends on the design but many meters have needle bearings which
564. test equipment available at the time URM 25 s While try to keep the filaments glowing and avoid transistor IC based radios in my setup do use more modern test equipment Date Fri 13 Feb 2009 13 12 45 0500 From David C Hallam lt dhallam rapidsys com gt Subject Re R 390 test equipment question That s the reason got the 8708A phase lock synchronizer to keep my 606B signal generator on frequency Of course they fill up a big spot on the bench test gear page 179 Date Fri 13 Feb 2009 12 22 42 0600 From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 test equipment question Actually a good HP 8640B can be had on ebay for fairly cheap don t go to Fair Radio though not the place to buy test gear except maybe scopes The 8640B is an analog sig gen but has a lock feature that will lock it down to the dialed up freq so no problems with drift would imagine a working example could be had for less than 400 didn t like the URM 25 either and got rid of it quickly The HP 606A and a freq counter was a better solution and then added the 8640 Date Fri 13 Feb 2009 12 27 02 0600 From Tisha Hayes lt tisha hayes gmail com gt Subject Re R 390 test equipment question What is really cool is to buy a surplus Efratom rubidium frequency reference that has a 10 MHz output approx 100 All of the HP gear I have has a frequency reference input to the counter scope and oscillator are all u
565. test gear page 1 TEKTRONIX PRIMER ON PROBES ETC When the probe is first connected to the oscilloscope compensate it by applying a low frequency square wave 1 to 10 kHz normally to achieve the equalization of time constants Improper compensation will result in either overshoot roll off or incorrect signal amplitudes see Compensation Effects figure Probe Accessories The charts on Oscilloscopes to Probes Cross Reference give you information on specifications oscilloscope compatibility and obsolete probe replacements to help you select the right probe for your application Consider the Following Factors in Making Your Probe Selection Match Probe to Scope Input Resistance and Input Capacitance Be sure the desired probe will match the input resistance and capacitance of the oscilloscope being used Fifty Ohm scope inputs will require 50 Ohm probes One megohm scope inputs will require 1 megohm probes Also check for connector interface compatibility or choose the appropriate adapter required 1 megohm inputs may also be used with appropriate 50 Ohm adapters Match to Scope Bandwidth and Rise Times Select a probe with adequate rise time and bandwidth for the oscilloscope and application Probe Loading Effects Minimize probe loading effects by selecting low impedance test points Although the input impedance of a probe is made as high as possible it still will always have some finite effect on the circuit under test Usually c
566. test gear page 176 module from the unit but keep it plugged in and up and running believe it was Fair Radio that used to sell a connector kit for making these up Date Fri 13 Feb 2009 09 52 33 EST From DJED1 aol com Subject Re R 390 test equipment question think you ve got all you ll need for troubleshooting the radios Almost all of the troubleshooting is checking tubes measuring voltages and injecting signals don t remember touching mine with an oscilloscope although it s the next acquisition would recommend guess the audio oscillator would be helpful for troubleshooting the audio section although haven t seen much discussion of audio problems over the years I ve found my Tektronix 2215 to be good It s a60 Mhz scope small and light and sells for 100 200 lately For the audio oscillator started with a boatanchor TS 382 but replaced it with a smaller solid state unit so there was room on the bench for the radio You can probably pick up a good small HP for 50 Enjoy the radios Date Fri 13 Feb 2009 10 59 46 0500 From Tim Shoppa lt tshoppa wmata com gt Subject Re R 390 test equipment question think any excuse to get an HP 200AB or 200CD is worth it They do remarkably well at staying constant amplitude as you turn the dial or flip ranges The light bulb in a Wein bridge is hard to beat Date Fri 13 Feb 2009 11 14 28 0500 From David Goncalves lt davegoncalves gmail com gt Subject R
567. th the complete MK 288 accessory kit and HP 608C for boatanchor and most HF shop work Using a lab grade step attenuator Daven 651 50 and an ancient Ballantine 300 audio VTVM find that accurate repeatable measurements down to the 138dBM level are possible Leakage is pretty well eliminated by the use of some surplus HP 50 Ohm cables Equally good results are had with some surplus DEC Belden 50 Ohm double shielded extra flexible network RG 58 size cable have also found that clean BNC connectors with no tarnish are necessary for maximum performance have not tried RatShack or similar import connectors Is the unbalanced input a nominal 50 Ohms Has anyone ran a network analyzer plot find no real info in the depot manual Also would think that the purist could easily whip up a 50 to 125 Ohm balun if that is the better input choice and if the URM 25D MK 288 kit is not available Date Sun 2 Jan 2000 01 05 59 0800 From Glen Galati lt eldim worldnet att net gt Subject R 390 Mk 288 URM test gear page 274 Speaking of the MK 288 Accessory Kit Does anyone know if there is a separate ArmyT M NAV Ships USAF T O for this item Equally good results are had with some surplus DEC Belden 50 Ohm double shielded extra flexible network RG 58 size cable have also found that clean BNC connectors with no tarnish are necessary for maximum performance have not tried RatShack or similar import connectors Is
568. th the selected tap driving one grid of a twin triode the other grid of which was grounded In the preferred embodiment the tubes were deployed as cathode followers with the meter between the cathodes with appropriate scaling and zeroing circuitry A schematic of a typical cathode follower VTVM can be found here http www mcemiv org Archive TestEquipment Heath_IM 18 gif Note 7 indicates that the indicated voltages were measured with a VTVM or 20 000 ohms volt meter Other designs the RCA Senior Volt Ohmyst comes to mind put the meter in the plate circuits See http oama edebris com download rca wv98c rca_wv 98c pdf This doesn t do any useful amplification of the measurement input but it does amplify the DC errors in the tube circuitry itself Consequently range and zero drift all over the place on these meters If you have a plate circuit VTVM you can cure this by converting it to cathode follower operation The same is true of the analogous FET VOMs Date Sun 4 Jan 2009 15 50 36 0500 From Roy Morgan lt k1 lky earthlink net gt Subject Re R 390 R 390 C101 and C103 Caps gt gt am a big fan of VTVM meters lt snip gt Tisha s being a fan of VTVM s may well be based in part on an aspect not mentioned yet in this thread DVM s of the modern sort have no resistor at the end of the test leads VTVM s of the kind common at the time of the R 390 s did The non isolated test probes whether having test prods or clip le
569. that you have should work fine for what you want to do You should consider it as a start You might want to keep your eyes open for good deals on older analog meters for your bench though use a couple of NASA Michoud surplus tube type Hewlett Packard analog meters that I ve rebuilt and calibrated as my primary BA bench meters Both of these are available today for pretty much next to nothing up to say 25 00 each The 400H is used for measuring AC voltages with frequencies up to about 4 MHz Max voltage is 300 volts and on the lowest scale FS is 0 001 VAC use the 412A for measuring DC voltage resistance and current It ll handle a max of 1 amp as far as current and has FS ranges from 001 VDC to 1000 VDC For resistance it ll measure up to 5000 Megs and is very handy when looking for leakage and insulation failures in coils and transformers etc A lot of super high quality older instruments are available pretty reasonable for making more precise measurements I ve got a pair of Leeds and Northrup resistance bridges that are slow as hell to use with their galvanometers but will measure down to a thousandth of an ohm Weren t you always curious at the resistance values of the test leads for your meter lt grin gt Both are still well within their accuracy specs of 15 100 of a percent Pretty slick for oak boxed gear that looks like it s out of the 1920 s Actually these are mid 1960 s vintage paid 5 dollars for one and 10 for the ot
570. the 51 manual from RadioEraArchives 51 Ouch Seems kinda high but who cares what they sell it for everybody s permitted to shop around That s right Some copiers will copy the blue though recall those were the ones which used a white light source as opposed to the ones with greenish exposure lamps Look for those if you need to copy such things Date Mon 19 Jul 1999 11 07 14 0600 MDT From Richard Loken lt richardlo devax admin athabascau ca gt Subject Re R 390 Tek scope 502A Those are called dual trace scopes not dual beam scopes Philips used to make some dual beam scopes back when was in technical school circa 1970 Nice scopes which put everybody to shame except Tek and HP in that order Date Mon 19 Jul 1999 14 14 13 0500 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Tek scope 502A test gear page 4 It s been a few years since I ve owned any of them but seem to remember that Tektronix actually used the wording Dual Beam on the front panel and in the manuals to differentiate between them and the less expensive Dual Trace scopes The CRT used separate guns and deflection plates for each of the two channels for a really nice non flicker display You could set one beam to sweep at say a second and the other at a ms and each trace would display 100 of the time there was no switching back and forth It s too bad that the bandwidth of the 500 and 502A were only a Mhz or so Come to think
571. the Eicos were much better than the Heathkits although the 324 had its own character was lucky to find a General Radio 805 C in need of TLC not too long afterwards Now THAT was a boatanchor Over 100 pounds IIRC It came to me along with a 1606 A RF bridge and a Millen grid dip meter and they all served me faithfully for a couple of decades still have the Millen Date Fri 14 Jan 2011 03 50 47 0600 From lt kaQ9egw britewerkz com gt Subject Re R 390 HP And Other Signal Generators I m still using the Measurements 82 bought 20 years ago at a hamfest for 25 From Michael OBrien lt mikobrien yahoo com gt Subject R 390 Fluke 6060a an or hp 8640b To r 390 lt r 390 mailman qth net gt have both a Fluke 6060A AN Calibrated and 2 HP 8640B might need to sell one of them Any opinions on one which should keep They are both used as as general RF signal generators for AM and FM work The HP s do have option 1 test gear page 239 Date Fri 14 Jan 2011 08 50 32 0500 From Shoppa Tim lt tshoppa wmata com gt Subject Re R 390 HP And Other Signal Generators use my HP 200CD for 455 kHz IF alignments My first 160 M QSO ever made using my HP 209 as a 160 Meter VFO The above are normally thought of as audio signal generators but they do great for radio work too They are exceptionally fine instruments Nobody knew how to build Wien bridge oscillators and RF signal generators like HP
572. the basic design for the TV 3 TV 10 settings data file It will be very similar to the ones I ve done in the past for the TV 2 TV 4 TV 7 and I 177 series testers suspect that there is published settings data a lot later that what have access to so I m waiting before start typing everything in so I m still looking for more settings data before start on the file The latest roll chart that have is May of 1966 It also appears that all of the TV 3 and TV 10 series models were different from each other mechanically and electrically When first started this project had test gear page 266 zero experience with the TV 10 series and assumed that there would be minor differences as there are between the various models of the TV 2 TV 7 and 177 series but it appears that the differences are much greater than that I m very curious about just how many TV 3 and TV 10 series testers were built They re scarce as hell in my neck of the woods and it s very seldom you see one advertised for sale anywhere across the nation There isn t a whole hell of a lot of data known on these models as far as production numbers suspect that the total production numbers are probably much much lower than the I 177 TV 2 and TV 7 series I d appreciate hearing from any of you that own TV 3 or TV 10 series testers along with the information that is on the nomenclature tag We re attempting to put together a list on these models with high SN s etc
573. the crud off the elements without opening them up This method is what was used by the old CRT Beamer devices of the 50s and early 60s Again should be applied to a tube that is otherwise already shot as if it rips a grid which can and does happen then the tube is a paper weight Again as noted this is a voltage blast hopefully so short the arc doesn t burn through stuff Date Mon 6 Aug 2012 14 10 19 0700 PDT From Steve Toth lt stoth47 yahoo com gt Subject R 390 TV 7 micromhos Thanks to Francesco in Italy the internet is a wonderful thing He emailed me a tip to look in the 35 manual for the TV 7 for a chart that converts meter readings to micromhos Page 7 of the 35 refers you to paragraph 20 of the 12 manual Operator and Organizational Maintenance Manual looked it up and there it was for each switch range Very cool Both manuals are on the BAMA site test gear page 405 Date Mon 06 Aug 2012 17 28 43 0400 From k2cby lt k2cby optonline net gt Subject R 390 TV 7 Micromhos Here is the table Transconductance Measurement with the TV 7 Tube Checker Use the following table to convert the meter reading to transconductance in u Siemens uMhos Meter Reading Transconductance Siemens uMhos Range B RangeC RangeD Range E 0 0 0 0 0 10 250 500 1 250 2 500 20 500 1 000 2 500 5 000 30 750 1 500 3 750 7 500 40 1 000 2 000 5 000 10 000 50 1 250 2 500 6 250 12 500 60 1 500 3 00
574. the unbalanced input a nominal 50 Ohms Date Fri 07 Jan 2000 09 35 15 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 Signal generator connection questions gt use both a URM 25D with the complete MK 288 accessory kit Not a very common kit gt built a DA 121U 50 120 ohm matching adapter a while back using an extra gt URM 25F adapter can What other adapters are in the MX 288 I m not really interested in the cabling or coax adapters just the cans gt find that accurate repeatable measurements down to the 138dBM gt level are possible Leakage is pretty well eliminated by the use of gt some surplus HP 50 Ohm cables I ve found that one of the best things that anyone that plays with very low signal levels can do for their URM 25 is to replace the coax of the three jumpers Ditto for the internal piece of coax that connects to the attenuator pad suspect that people using the 30 and 40 year old original coax is one of the things that led to the bad reputation of the 25 s when dealing with very low signal levels figure that not only is the stuff old enough to vote but it s probably been bent and flexed a jillion times It s amazing how much debris and oil film etc can end up inside of the attenuators in the URM 25 s I ve also seen contacts in them that weren t adjusted right or where dirty and would have measurable resistance levels Some as high as 30 ohms of so Not good f
575. there is mention of a Oscillator Filament Regulator Assembly AN URM 25H only My 25D has this board so at some point it has been upgraded to the H version This board is connected to the filament of V101 6AH6 So maybe someone working in one of the repair depots at this time periodcould give a little insight More info Beg borrow or steal a copy of Dallas Lankford s notes on recapping the URM 25D While looking at a scope connected to my 25D the modulated waveform left room for improvement the top of the waveform was fine bottom of the waveform wasn t modulated the same less and distorted After recapping life was good Well worth the money spent and think this sig gen is ready for another 50 years can t say the same about my HP 8640B Date Fri 1 Dec 2006 17 44 04 0500 test gear page 362 From Larry KW4A Subject R 390 Lankford s notes Anyone interested in a copy of Lankford s notes on the URM 25D contact me off list Date Fri 01 Dec 2006 17 23 25 0800 From Kenneth G Gordon Subject RE R 390 URM 25 generators and Ashley don t remember which model my AN URM 25 is but it is a good one think it is a late G model intend to send it over to Ashley in Washington asap to have her rebuild restore it since it has seen heavy use for the past 10 years or more She has the tools experience and time while although have the experience sure as heck don t have the time right now have seen some
576. these components are are well documented Beyond these see no reason to replace anything that hasn t given you a specific reason except perhaps the electrolytic power supply caps which might justify replacement just on principle Tubes in particular with a precious few exceptions don t need to be changed for the heck of it In most cases they don t even need to be replaced when a tube tester says they are weak With the exception of the first RF tube all the tubes in a 390A can be dead flat 25 or less on a good tube tester and the radio will easily meet its specifications know once filled a 390A with dead flat tubes on purpose and measured it Time was when one might replace all of the tubes just so you wouldn t have to think about them again for a decade or three Nowadays however many of the new tubes available even lots of NOS tubes are not reliable the new tubes because they are not made to a high standard the NOS tubes because they have been leaking ever so slightly for 30 60 years and now have less than perfect vacuum So often the tubes in the radio are as good as you are going to do in terms of future reliability test gear page 181 The real bugaboo in 390s and 390As are the crystals which have aged all out of spec by now If wanted to refurbish a 390 or 390A I d start there if you can find anybody who can supply quality crystals today I ve heard mostly horror stories the last ten years or s
577. they used to You can t trust tubes even if in the original box From time to time we come across bad batches or might be just one bad one in a sleeve of five Side trip We had the same drugstore testers here in the States They had just a few controls and lots of sockets and a roll or flip chart Usually mounted on top of a metal cabinet with a stock of the most popular tubes They were very simple emissions testers have a couple of them some made by Mercury here Most of the time they were calibrated to err on the side of higher tube sales but due to limitations they often failed to detect defects They strapped a lot of pins together for the test They would also show bad horizontal output and high voltage rectifiers to be good when they were really bad don t think there are any regular testers that do these Often they were broken down burned out transformer due to a careless customer The typical customer was test gear page 151 so happy that the tube he thought he needed was in stock he usually didn t complain about the inflated price and might buy two or three additional tubes just in case There was a different kind of tube jockey here as well The guys who came to the house to fix your TV set That might have been sometime after one pulled all the tubes from a set put them in a shoebox or paper bag and trotted them down to the electronics or drug store and found none to be bad due to bad horizontal output
578. thing Date Tue 10 Nov 2009 09 19 39 0500 From Barry lt n4buq knology net gt Subject R 390 OT bought a scope test gear page 209 bought a Tektronix 465M a k a AN USM 425 V 1 from eBay see item 350273674446 When saw the trace figured the image was shot with a shutter speed about 1 250 second and with the sweep time set to 50ms that would have been about the length of trace shown approximately 8 100 of the horizontal scale copied the picture locally and examined its properties It turns out the image was shot at 50ms 1 20s so looked back at the photos and noticed the delay time UNCAL lamp is illuminated Given a 50ms shutter speed and the trace covering approximately 8 100 of the horizontal scale then if did the calculation correctly the sweep speed would be about 625ms l m not all that familiar with this scope but assume the sweep can be slowed to that speed at least in the 50ms setting Is this a correct assumption ask because hope the scope is not too broken if broken at all Obligatory R390 reference Well maybe I ll use it to look at something on an R390 A one day Date Tue 10 Nov 2009 10 34 51 0800 From Dan Merz lt mdmerz verizon net gt Subject Re R 390 OT bought a scope Barry my 465 DMM manual shows a factor of 2 5 for the uncalibrated range This would extend the 50 ms to 125 ms think you re trying to account for another factor of 5 beyond that In looking
579. this group Is there anything to look for in getting one up and running Any caps that did to be changed Any special tricks needed for calibration Any help greatly appreciated From Michael Melland lt w9wis charter net gt Subject Re R 390 ME 26D U Date Sat 17 May 2003 17 04 48 0500 test gear page 85 The ME 26D U is a militarized version of the HP 410B had one and the probe tip was broken off too just took that cap off and made a new probe tip and installed it The manual is available on the net if you need one It serves as the maint manual for both the 26 and 410B Hardest part of the meter to find will be a probe diode tube It s a Eimac 2 01C and I ve seen them listed for up to 125 each if you can find one have several nos don t think they ever switched the 26 to the EA 53 like HP did that s even rarer and more expensive From Kurt lt r390auser cox net gt Subject Re R 390 ME 26D U Date Sat 17 May 2003 16 09 01 0700 Please tell me how you made your new tip for the RF probe Looking at the inside of mine all of the metal parts seem to be potted and do not turn even though from the outside the tip appears to be threaded You are correct in that the D model has a different RF probe from the HP 410B Is it possible to put a 410B probe on the ME 26D U The two different rectifier tubes you mention do not appear to be interchangeable Any thoughts on this From Steve Hobensack lt
580. times be cured by adjusting the ONE BALL rear tuning shaft adjustment This is the shaft that carries the single knob on the front panel There is a single ball bearing at the rear end of that shaft with a slop adjusting mechanism The tell tale symptom is that when you push and pull gently on the frequency set knob the frequency changes as you do Use CW mode on your receiver suggest hat when adjusting this thing you get the thing plenty warmed up before you take it out of the case Mechanical play may change when it s hot test gear page 367 There may also be a spring or adjustment that adjusts the mesh between the worm gear on that shaft and the main tuning large gear This seems to be what you found in your F model The large gear MAY be of the spring loaded anti backlash type I can t remember These would be two different situations The F model has a different shaft arrangement on the tuning knob but can t remember the details have a D model that needs to be taken apart for attenuator repair someone smoked it on one position have another URM 25 handy but I m not sure if it is an F Does anyone know if the attenuators can be swapped gt It was not even touching so adjusted it down a little bit put it back gt together and have no RF output now Uh oh Something went awry Do the tuning cap plates now rub Was the adjustment on the tuning knob shaft or on the main capacitor gear shaft Maybe you lost a ball bear
581. tings other settings look like noise on the scope gt gt If the voltage looks about right on those ranges gt with a 50 ohm load the peak voltage on the scope ought to be 1 414 times gt the meter indication the meter is calibrated for RMS and then somebody gt may have keyed a transmitter into your attenuator when it was set to gt one of the lower ranges This would probably have fried some of the gt resistors in the attenuator It HAS to be terminated with the 50 ohm load which don t have yet opened the attenuator and checked the resistors they measure OK will try it again with the proper load when get it it will probably work right then gt The RF output should be a fairly clean sine wave test gear page 270 gt Mine has some distortion on the negative peaks don t know gt whether this is normal probably not but it isn t too bad so I ve never gt worried about it much Mine shows distortion along the sine wave it just makes a wide trace at a higher sensitivity setting one can see harmonics gt The attenuator is easy to take apart The resistors gt are small like maybe 25w and appear to be metal film They will gt take quite a bit of abuse before they change value so if one looks gt burned measure it before you give up think after seeing them that 0 25 watts is optimistic They d be tough to change Interesting that the manual says to use a hot soldering iron to minim
582. tings data and the inaccuracies that result On a side note I ve yet to receive any reports of errors in the public release beat of the TV 7 series settings file that have for download It s been a couple of months since it s release Is anyone looking for typos Date Sun 18 Feb 2001 17 26 46 0600 From John Watkins lt jwatkin9 swbell net gt Subject R 390 British Tube Testers have noticed that a few folks are looking for tube testers Don t forget that our British cousins also made some really good ones that have been available off and on over the years have a CT 160 made by The Automatic Coil and Winder Equipment Co Ltd Winder House London SW 1 that works just fine picked it up while living in London Does anyone have any of the documentation on this unit have a book that has the various setting for both European and American tubes guess that should scan it and send it to Nolan as soon as get the chance Date Sun 18 Feb 2001 21 05 03 0500 From Meir Ben Dror lt mbendror optonline net gt Subject RE R 390 British Tube Testers Don t forget to mention the British AVO MkIII tester think it s one of the best tube testers in existence have a TV 7 and an l 177 tube tester and also a few test gear page 51 flavors of the average commercial tube testers The one like to use the best is the AVO Date Sun 18 Feb 2001 21 08 25 EST From Llgpt aol com Subject Re R 390 British Tube Testers
583. to get in to clip out the 0 01 uF Black Beauty caps across the AC line it s scary to think what those things must be leaking to the chassis ground Date Fri 4 Mar 2011 22 47 59 0500 From Barry lt n4buq knology net gt Subject Re R 390 OT HP 410B Tubes It wasn t too hard to do If you remove the switches pots and panel lamp from the front panel it all comes apart pretty readily In order to replace the bypass caps on V2 had to remove the screws that hold the resistor board and move it out of the way as much as possible After that it s not too bad Mine had the monolithic style 1uF Sangamo filter cap used the existing mounting screw holes to mount two old style solder posts and the new filter cap fit right between them had to splice one wire to get it to stretch to one of the posts didn t want to clip all the lacing just to get some slack in that wire One of those Black Beauties was leaking both physically and electrically it made a pretty nice 82k ohm resistor didn t replace them as the newer models didn t include them anyway It was suggested to me to remove the 50uF cap across the meter it isn t on later models however opted to replace it with a 47uF as like the extra damping it gives to the movement Date Fri 4 Mar 2011 23 21 43 0500 From Steve Byan lt stevebyan verizon net gt Subject Re R 390 OT HP 410B Tubes Thanks now that you point it out it s obvious Date Thu 30 Sep 199
584. to the DC removed to keep the same resistance That extra use for the very low current fuses didn t lower the price from several bucks a fuse Probably the blown fuses shouldn t be tossed but taken to a jeweler s for reclaiming the platinum Platinum was used in the 1 and 2 maybe 3 ma fuses don t know if it still is but if they are more than a few bucks a fuse it probably still is Date Tue 25 Jan 2000 19 12 29 0600 From Nolan Lee lt nlee gs verio net gt Subject R 390 I 177 series setting data Still not bad If you get a chance ease on over to my I 177B page at either http www acadiacom net nlee i177_index html or http nhome gs verio net nlee i177_ index html test gear page 253 and download the I 177 tester setting data that did last year combined the settings from about a dozen different military manual and supplements and the commercial Hickok manual for the I 177 type into an Excel workbook format The latest data was from 1957 if remember right The version did contains thousands of lines of setting for use with both the plain I 177 series and for the MX 949 adapter box There s also instructions for building the adapters to test 5814 s and 12AU7 s in the standalone I 177 In the event that you don t have or don t use Excel you can hit the Microsoft home site and download a free viewer for Excel Date Tue 25 Jan 2000 19 36 57 0800 From B L Williams lt B L WILLIAMS prodigy net gt Subject Re
585. to work with back in the 50 s and 60 s We cannot forget that there are pieces of modern test equipment that will surpass the capabilities of a good old VTVM for certain applications Date Sun 04 Jan 2009 13 55 39 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 R 390 C101 and C103 Caps gt am a big fan of VTVM meters for high Z measurements where the gt loading on a circuit by a DVM really throws off a reading hesitate to say all without checking but believe all of my DVMs have 10 or 11 Megohm inputs VTVMs are generally 10 Megohms know the ones use regularly do gt From an aesthetic standpoint a tube meter with a mechanical gt movement is what the R 390 was originally designed to work with gt back in the 50 s and 60 s I m not sure the radios were really designed to work with d Arsonval VTVMs so much as those were what was available at the time Don t forget there were also non buffered VOMs in use too Indeed most field level maintenance on R390s was almost certainly carried out by radiomen with VOMs Sometimes test gear page 173 one finds a designated test point that the manual notes must be measured with a high impedance meter to avoid loading error or a note regarding what kind of meter was used to obtain the listed voltages but often it was left to the tech to know Note that there were two basic designs of VTVM Both used a 10 megohm or so divider string on the input wi
586. tolerance as the generator which is also referenced to the shop source Date Mon 10 Jan 2011 14 45 08 0500 From wa4aos aol com Subject R 390 8640B have 4 8640B s in my electronics lab and use them often have them set up on various benches and that makes service burn in and evaluation all possible with minimal moving units around bought two of the from George Bojr in Texas and he has repaired another one for me He has parts for the 8640B and does a GREAT job with service The turn around was quick and was very pleased You can find them cheaper on ebay but understand you may get a dud and or one with split gears and other issues George can not give you a NIST sticker but his equipment is calibrated and all of my units are dead on between units He does sell on ebay but may have inventory for sale at any given time Personally like the 8640B for receiver work They are accurate dependable and small compared to older units like the 606A B You can also use it s internal counter for external measurements so it s really two pieces of equipment though have other counters Typically let them warm up half an hour before do any serious alignments as would no matter what generator use Like most HP gear the 8640B accepts and external 10MHz reference input should you care to do that bought one of the 10MHz GPS receivers on ebay with antenna for around 150 and build an adequate distribution unit to reference
587. ts Problem is the hold down not the pin terminals of the 7 pin socket It s rather soft and loosens up from plugging and unplugging the tubes The socket saver fastens to the bakelite or ceramic part of the original socket through the center bolt nut When you pull out a tube it puts stress on the original socket and mount secured it with some gimmickry Probably not the problem this time besides the new tubes and some of the old test OK no shorts for the same tube type Maybe leakage on the switch contacts as was suggested From mikobrien att net Date Sun 06 Jan 2002 02 15 59 0000 Subject R 390 calibration for simpson 260 6 series Does anyone have or know the calibration procedure for the Simpson 260 6 series VOM From Al Parker lt anchor ec rr com gt Date Sat 5 Jan 2002 21 30 47 0500 Subject R 390 Re BoatAnchors calibration for simpson 260 6 series I ve got a manual for a 260 series 5 if that ll help can scan amp send the cupla pgs that cover the calib procedure after replacement of rectifiers and the other svc stuff From Scott Barry Clyde B lt cbscott ingr com gt Date Mon 4 Mar 2002 13 33 42 0600 Subject R 390 ME26 D U test gear page 62 Anyone know anything about this VTVM bought one recently and it looks like it may be an HP410 in different packaging The manual have with doesn t include a schematic but the revisions that are included picture an HP410 instead of the
588. tter generator Yes know if wanted to spend a lot of cash could get a generator with more stuff but for 25 this one might be good enough for general use bought a really nice General Radio capacitor analyzer from the fellow and among the other stuff he had this generator caught my attention but wanted to know more about it before getting it Date Mon 11 Jan 2010 23 27 46 0500 From 2002tii lt bmw2002tii nerdshack com gt Subject Re R 390 OT Wavetek function generators Most of their stuff is decent but nothing to get excited about maybe a half notch better than Leader and B amp K Dynascan or maybe not The 114 and its non sweep brethren are basic function generators familiar to thousands of engineering students their primary mission was as low cost generators for university engineering and science labs What do you want to use it for As a source of audio signals to feed into circuits you are building or to modulate an RF generator it should do fine If test gear page 212 you hope to feed an IF or HF signal into a radio for testing and alignment you will find that all general purpose generators have way too much FM and drift to make you very happy For that you need a proper RF generator where money has been spent on careful frequency control particularly the mechanical and thermal design You d like your RF generator to exhibit stability and freedom from drift that are better than the VFO in the radio yo
589. tubes can have gone gassy in a year Check for a positive grid voltage when the cathode has been hot a while Date Sat 25 Nov 2000 21 58 54 0700 From Kurt lt radiouser uswest net gt Subject Re R 390 TV 7 Shorts Problem Check your line voltage setting have seen where too high of a line voltage setting will cause shorts to show up where there are no shorts Date Sun 26 Nov 2000 18 45 17 0500 EST From Norman Ryan lt nryan duke edu gt Subject Re R 390 TV 7 Shorts Problem recall a similar problem with my TV 7D U You do a lot of turning of the FUNCTION SWITCH knob right do as well when doing the full monty tube test Open up the tester and blow out any dust or contact wear from said switch got compressed air then spray some DeoxIT in there Apparently contact wear produces enough metallic bits to cause false positives Let us know how you make out Date Sun 26 Nov 2000 19 04 28 EST From Llgpt aol com Subject Re R 390 TV 7 Shorts Problem Good advice Norm a shot of De Oxit works wonders many times test gear page 259 Date Sun 26 Nov 2000 20 19 52 0500 EST From Norman Ryan lt nryan duke edu gt Subject Re R 390 TV 7 Shorts Problem Thanks BTW DeoxIT shouldn t harm the TV 7D U switch as its wafers are ceramic R 390 switches don t like DeoxIT on their phenolic wafers Dab the contacts only and sparingly Date Sun 26 Nov 2000 20 33 54 EST From Llgpt aol com Subject Re
590. tween series and parallel resonance Parallel resonance is found by the notch in the same set up Date Mon 10 Jan 2000 10 45 16 0500 From JAMES T BRANNIGAN lt JTBRANNIGAN prodigy net gt Subject Re R 390 Signal generator connection questions gt Also how does one set the frequency of the URM 25 D gt to 455 Hz exactly without a freq counter Even with a counter connected the URM 25D is REAL touchy at 455khz and unless it is warmed up for a while it will drift So check your settings often I m refurbishing my CV 591 It needs audio caps and a new volume control These are on order from Mouser and SSofN BTW connect the AGC from the CV 591 to the R 390A It works just fine Mon 10 Jan 2000 20 50 50 EST From DJED1 aol com Subject Re Re 2 R 390 Signal generator connection questions Here s what know The nominal balanced input is 125 ohms The original specs to which the nonA was designed called for 125 ohms plus minus 15 with no more than 20 ohms of reactance The final acceptance spec for the production radios was 50 ohms to 375 ohms up to 16 MHz and 100 to 700 ohms at frequencies above 16 MHz mention this because the only info have on the unbalanced input is from the original spec which may not represent the actual radio We know the unbalanced input is high impedance connected to the grid of the first RF tube The original spec called for the unbalanced input to operate with antenna impedances from 1
591. u are working on General purpose function generators are several orders of magnitude worse than an R 390 A PTO in this regard Date Thu 18 Feb 2010 20 27 08 0600 From Barry lt n4buq knology net gt Subject R 390 HP 8640B Question think some folks on this list have HP 8640Bs so thought might indulge those fellas a second think understand that there s a rather delicate gear that frequently breaks in these units When that occurs what are the symptoms Is this by any chance directly related to the frequency change knob In other words if this gear breaks completely would the frequency change knob work at all Also seem to recall that someone made some replacement gears Was it someone on this list Thanks in advance for any info on this Date Thu 18 Feb 2010 18 50 40 0800 From Scott Overstreet lt scott becklawfirm com gt Subject Re R 390 HP 8640B Question First Barry open it up all the gears are in plain site Now all By all means yes If you know where replacement HP 8640B gears can be had please tell us all for one have an 8640B with wired together gears and love it The 8640B is a terrific instrument and I d like to keep mine running as long as am runable Date Thu 18 Feb 2010 22 27 32 0500 test gear page 213 From rbethman lt rbethman comcast net gt Subject Re R 390 HP 8640B Question There has been a LOT of discussion about these nylon delrin gear on t
592. uare wave look square through the probe And the probe loading on the oscillator probably comes from that oscillator test point having RF on it You can calibrate the DC on the VTVM using a NEW never loaded C or D cell probably not alkaline Heathkits were calibrated by setting the new cell to indicate to a little red dot on the right side of the meter on the 1 5 volt scale Heath claiming the new cell was 1 54 volts A mercury cell was generally more predictable at 1 4 volts but new mercury cells are extinct They leaked mercury into the environment when smashed between hammer and anvil There is some loading of some circuits by the VTVM but the normal voltage readings test gear page 48 charts were made with the VTVM so the loading effect is included Using a different meter will lead to different readings that may NOT be wrong just different from meter loading noticed some errors in the voltage charts of TM 11 5820 357 35 edition of 9 March 1962 for the R 390 URR where some places it puts the unregulated DC at 395 volts instead of the 295 it should be Date Mon 22 May 2000 09 57 57 0500 From Dr Gerald N Johnson lt geraldj ames net gt Subject Re R 390 Instruments Switchable probes are often the worst at having lots of input capacitance on either range Direct probes are guaranteed to have lots of input C Date Sat 10 Feb 2001 15 17 23 0600 From Nolan Lee lt nlee gs verio net gt Subject R 390 TV 10 settings fo
593. ube Date Tue 18 Sep 2007 08 57 12 0400 From Gord Hayward lt ghayward uoguelph ca gt Subject Re R 390 OT 30V regulator Zeners are good For 48 52 voltsYou could use a 48 v zener and bias its ground point with an adjustable regulator For 1 5 v use a couple of 1N400x in series not bang on but close horseshoes hand grenades and drive in movies I ve built regulators with an op amp and a big pass transistor The trick is capacitors in critical places the transistor base and a BIG one on the output to keep it stable Date Wed 19 Sep 2007 22 46 11 0700 PDT From Perry Sandeen lt sandeenpa yahoo com gt Subject R 390 RE 150 Volt regulator Wrote If BIG IF you wanted to solid state the OA2 the right choice truly is a solid state shunt regulator developed a SS OA2 shunt regulator using the TL431 Inspiration by Dr Jerry who is sorely missed Reply off line for a PDF file of about 100K if interested Date Thu 11 Oct 2007 22 18 32 0500 test gear page 165 From Glenn Little WB4UIV lt glennmaillist bellsouth net gt Add to Address Subject Re R 390 Re query over North Atlantic 213C OT saw this while going through some old email The Phase Angle Voltmeter is used in aligning servo and synchro systems We used them in the navy to align the fire control RADAR and ECM synchro and servos There may be other uses Date Sat 27 Oct 2007 21 31 51 0400 From Richard Spargur lt k3ui
594. ubes to read weak test gear page 135 K he ee B ili ee Replacing the 83 with Silicon Diog i mercury vapor rectifier in a Hickok wi p Replacing the A saves 15 watts of power transformer of silicon 2 for higher power tubes without lighting the po loane ae of IN4007 diodes can be wired from Pins 2 and3 amp i ro the transformer center tap Or the diodga the 8350C n tube base as a plug in adapter ifa Pair of tp wyatt resistors is added as an artificial center tap ti ohm t ecessary OF advisable to replace the 5 3 With sift des The diodes have much less voltage drop which wodd diodes dding extra resistance In series and the line test faa nc a certain constant power drain to work Properly ris not n require a tion assumes test gear page 136 From Francesco Sartorello lt francesco sartorello virgilio it gt Subject Re R 390 re l 177 question OT Date Fri 24 Mar 2006 21 27 13 0100 It is the artificial center tap if you don t wanto to modify the wiring underneath the 83 socket get an old 4 pin base and wire it in accordance with the diagram replace the 83 with it and forget about the mercury vapor rectifiers have three TV7s with this device installed years ago and the power transformer runs much cooler Have a look at the text in the first pic Ciao Francesco Date Sun 26 Mar 2006 16 02 26 0600 From Barry lt n4buq knology net gt Subject Re R 390 HP410B rectifier tubes
595. uggest the use of an ESR meter on the electrolytic caps and careful measurement of leakage I use both an Eico 950B and Sprague TO cap tester at true working voltage 20 If the ESR is lt 3 electrical leakage minimal and the physical condition good I d continue to use the caps once they are properly reformed If the ESR is up or the leakage doesn t drop off in about 4 5 minutes I d get out the Dremel and rebuild the cap For those of you who don t have an ESR meter it is the most useful repair instrument own Especially for newer equipment with loads of poor quality electrolytic caps my Panasonic VCR immediately comes to mind Mine was a kit from Dick Smith Electronics in Australia and was only about 35 You can go thru a small PCB full of caps in a few seconds and identify likely suspects for quick replacement It is also great to carry at hamfests before buying lytics Date Fri 19 May 2000 23 05 43 0700 From Wayne Rothermich lt rother impulse net gt Subject Re R 390 Instruments gt am wondering about test instruments All of My old manuals call for the use of a VTVM can get numerous old HP VTVM s at the swap meets My question test gear page 43 is this do need a VTVM to properly read the voltages in My old stuff or will a modern multimeter meter do the trick If so gt what brand s would you suggest have burnt up My last Radio Shack piece of junk think all those manuals specify a VTVM so peop
596. ull the 25 D down For a good gas check let the tube cook five or ten minutes before testing can tell you that one thing that will drive you nuts as far as drift goes is a varying line voltage Let yours warm up good on a variac stick a counter on the output and vary the line voltage a volt or two in either direction It s not the B either that causes problem lt grin gt One of the things that was changed when the 25 G came out is a regulated filament voltage supply for the osc tube The way they did it was crude in that they added a 12 volt filament winding dropping resistors and two zener diodes guess that they got their idea from the Lucas charging system used by Triumph and BSA It generates a bit of heat can feel the difference in case temperature between the URM 25D and my URM 25G There were a few Govt and civilian mods to the power supply in the URM 25 using SS devices to regulate the filament voltage for the osc lt snip gt Did you run into any problems calibrating the RF voltmeter portion of your 25 D If so give me a holler can tell you how to fix it Date Thu 14 Dec 2000 01 10 56 0500 From JM CO lt jmerritt2 capecod net gt Subject Re R 390 URM 25 Stability This doesn t sound right You probably have some component s that are drifting with prolonged heat would suspect capacitors Tubes should be stable within 10 minutes or so both to operate and to test Date Thu 14 Dec 2000 08 03
597. unit have Just wondering Subject Re R 390 ME26 D U From Richard McClung Dielectric spx com Date Mon 4 Mar 2002 11 41 00 0800 lt snip gt You got it Electrically it s an HP410 The early models were exact HP s But you know how the military is They got to make it bullet proof From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 ME26 D U Date Mon 4 Mar 2002 13 54 25 0600 That s what figured don t like the packaging on the ME26 as well as the HP410 but this one is is great shape Looks like it was hardly perhaps never used In original box no less Hey look Here s an off the shelf unit that will work just fine Nah Use the design but get it from the lowest bidder Time to hook it up to the VARIAC and hope the caps are still okay At least this one has a complete set of probes Date Fri 08 Mar 2002 09 48 59 0700 From Jordan Arndt lt jordana nucleus com gt Subject R 390 TS 505C U Manual Is there an online source for a TS 505 C U VTVM Does anyone have a pic of the RF Adapter think this is the same VTMV that is listed as Required Equipment for the 390 390A service bench What is the input impedance resisitance 73 de Jordan From Scott Barry Clyde B lt cbscott ingr com gt To R390 E mail lt R 390 mailman qth net gt Date Fri 8 Mar 2002 11 03 52 0600 Subject R 390 Need Meter Repair Help recently acquired an ME 26D U VTVM It
598. up an HP 3586B Selective Voltmeter an HP 3330B Synthesizer and several Watkins Johnson counters The pile was less than 200 Manuals for this stuff will probably cost more than the equipment lt snip gt From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 Signal Generators was Deoxit Date Sat 29 Nov 2003 13 17 44 0600 Just as an addition to my earlier comments own both the 8640B and an 606A and love them both use them in my R 1051 business Know it s not proper to mention it a lot but purchased just about all the test gear own from the Auction site and have had nothing but good luck with the folks have dealt with Test gear is very reasonably priced there You can expect to pay probably test gear page 94 around 800 for a good working 8640B and can pick up a nice 606 when you can find them for no more than 100 125 usually found the URM 25 not as straight forward to use and had to keep opening it up to fix little problems that showed up prefer to fix radio s instead of test equipment From Cecil Acuff lt chacuff cableone net gt Subject Re R 390 Signal Generators was Deoxit Date Sat 29 Nov 2003 13 25 38 0600 Well just another update was wrong on the pricing of the 8640B s the market has gotten softer than knew Looks like one can buy a nice one for 300 to 400 bucks that is a steal of a deal on a very nice generator They were double that 2 years ago may
599. uper high gain plug in with that capability The coax cable for a probe has lower capacitance per foot than any other cable That s achieved by using a hair for a center conductor and foam for insulation The hair is made of the best quality steel or some tough alloy that can t be soldered Then for the attenuator probes there s a 10 meg wide band resistor with a fixed capacitor in parallel plus another variable capacitor usually at the connector end for matching the RC time constants of the scope plus cable to the probe and its capacitor In some probes the adjustment was at the probe tip Only a few manufactures make good probes The resistance of that center conductor confuses bandwidth Date Wed 03 Jan 2001 23 29 31 0600 From Nolan Lee lt nlee gs verio net gt Subject Re R 390 R 390A Manuals and O Scope For the money It would be tough to beat the full size Tektronix 7000 series lab scopes right now They re a bargain and a hell of a lot easier to work on than the little compact models Usually a lot less expensive too Most of the 7000 series scopes I ve seen were in a lot better condition physically since they weren t really portable and banged around a lot I ve standardized on the 7704A for now I ve got two that use as my primary scopes and one with a dead PS for parts guess that I ve got a couple of dozen working plug ins for them and another dozen for parts With a bit of luck these should take care of my scope needs f
600. ur PTO Date Wed 05 Sep 2001 20 07 44 0200 From Heinz und Hannelore Breuer lt hbreuer debitel net gt Subject Re R 390 recommendation for rf signal generater The URM 25 is a fine generator but might need some TLC Ask for the mods from Electric Radio on this list if you get one If you have a little more money to spend look for a HP 8640B They are getting cheaper and can be found around 350 to 400 even on eBay It has has all the features you want There was a military unit HP 8640B opt 323 which is even cheaper but looks ugly at least to my eyes One or two featurs are missing with the opt 323 units but can t remember exactly Date Wed 5 Sep 2001 21 40 55 0700 PDT From John Kolb lt jlkolo cts com gt Subject Re R 390 recommendation for rf signal generater Of course you can t measure frequency while the output is cranked down to a few microvolts the counters aren t that sensitive counter sorry bad pun this by running the generator at a high level output to a T connector one output to the counter and the other to an external attenuator a HP 355D 0 120dB in 10 db steps Sure beats turning the output level up to measure freq down to use up to measure freq again etc Good attenuators are available fairly cheaply at that auction place was just outbid for an off brand equilivent of the 355D which sold for 10 50 test gear page 324 Date Thu 6 Sep 2001 01 12 40 0500 From Bill Hawkins lt bil
601. ut for the cases and power supplies He had rat holed the good nice looking innards with panel and offered me one for 25 and said if it didn t work he d make it right If any of the list members are interested he talked like there were more So if anyone wants my TV7A sans meter but with the Army tech manual I d like 70 plus shipping haven t pursued the meter hear they re rare because I ve been using a Triplett 3444A Date Thu 8 Jun 2000 05 15 34 0400 EDT From Norman Ryan lt nryan duke edu gt Subject R 390 URM 25D Tweaks long winded version A URM 25D followed me home from Dayton along with other gear It was dirty had a zip cord soldered onto the power input connector and was missing its cover and accessories spotted it during the waning hours of Hamvention 2000 and got it for a song figuring it would be a handy parts source Just got around to cleaning it up and eyeballing the insides before performing a smoke test Was surprised how much cleaner the interior was than my working and complete unit Couldn t find anything wrong inside and it passed the smoke test was also struck by how smoothly the frequency adjust knob turned My bench unit s frequency adjust knob always was on the sticky side and because of it hated going through all those frequency changes during a full press R 390 alignment Putting a drop or two of my favorite lubricant Mobil 1 gear oil on the URM 25D s bronze bushing under the tuning k
602. ut these items is that they have monstrously high impedance when they are set to null keep thinking that would make them a very good thing to use as a high resolution meter to watch the AGC voltage on a R 390 Being able to say for sure that your signal report is 1 237 micro volts and doing it with a tube radio seems like a fun thing to do Date Tue 28 Sep 2004 14 12 30 0400 From Rbethman lt rbethman comcast net gt Subject R 390 TS 505 Manuals in PDF format available still have the TS 505 VTVM manuals available to mail to anyone whom asks for them They are zipped and are 711KB in size Date Mon 25 Oct 2004 20 48 57 0400 From Bob Camp lt ham cq nu gt Subject R 390 Tube Tester One of the truly amazing things about the current surplus scene is that a reasonable military tube tester say a TV 7 from the 1950 s sells for almost as much as a reasonable military radio Say a R 390A from the same era By the time you buy a reasonable set of test gear you have invested as much or more than you put into the radio So here s the question Is there any interest in a R 390A only tube tester As far as i can see you could make one with a handful of parts that would test all the tubes in the R390A except the rectifiers It should do as good a job as a TV 7 on the R390A tubes One advantage would be that the number of switches involved would be small The ease of use factor on the simple tester would be significant if you check
603. ution hook a low voltage power supply like a D cell in series with the DVM and the secondary That should give you about a milli amp though the secondary Unless this is a very low level transformer the current shouldn t bother it to much use a similar setup for checking caps on the R390 A 60 volt power supply a 5 micro amp DC meter and a 22 meg resistor all in series with the capacitor makes for a pretty sensitive ohm meter cap leakage tester You can use the same resistor in series trick to keep the current in the secondary low In that case probably would measure the voltage on the secondary and figure the resistance out by formula Figure that kind of stuff out for a living and they make you a Lord Don t know if that helps or not test gear page 106 Date Mon 12 Jul 2004 20 41 08 0700 From Dan Merz lt djmerz 3 cities com gt Subject Re R 390 DMM bounce Hi Joe my DMM is BK 2905 calibrated with dc and for ac with 400 hz have no idea yet of details on the other guy s meters except think they are autoranging type for ordinary dc and 60 hz measurements l Il try to get more details on his meter but don t think they are types for measuring much above 5 khz use my meter occasionally for measuring up to 5 khz though have no idea how accurate it really is up there but use it to get voltage ratios for evaluating audio transformers have checked it against my HP 403B meter and decided for what was doing it w
604. ve a frequency passband The typical panel meter used to measure say 0 to 150 volts AC will be accurate only at the 60 Hz AC power line frequency A voltmeter used to measure say 10 Mhz must have a passband going up to at least that frequency An excellent meter for this purpose is the Hewlett Packard model 410 C which goes up to I think around 700 Mhz The older and much cheaper model 410 B will work just fine too if you can find one that still works properly Chuck N1LNH Date Mon 24 Jun 2002 15 31 17 0400 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 URM 25D recap gt Yes an RF voltmeter is required here An excellent meter for gt this purpose is the Hewlett Packard model 410 C URM 25 Calibrators agree but there is more Indeed it is but what if such a thing is not available All is not lost Lets make some assumptions 1 High accuracy is not required 2 The voltmeter circuit in the URM 25 measures accurately enough for our purpose across the frequency range of the generator 3 If an AC meter is available that can measure well enough at a few hundred KC or even much lower then we can use it to set the URM 25 calibration 4 The manual for any meter that is available will give some idea of the accuracy to expect at a few hundred KC or lower If we can accept these ideas then the procedure would be as follows 1 Get whatever AC meter is available and figure out what accuracy you
605. w that there are other options for rf signal generators One thing that concerns me about looking at others is how well they will match up to the R 390A and will they have the right types of connectors I d like to be able to get one inexpensive enough that could afford a nice freq counter as well so could set the frequency precisely Please no comments from the peanut gallery about how only someone rich enough to afford the best equipment should be allowed to own a R 390A Date Wed 20 Jun 2001 22 04 50 EDT From DJED1 aol com Subject Re R 390 Thanks and Restoration Update Really not too necessary to have very accurate frequency for alignment purposes The internal calibrator can be used to check the received frequency then tune the URM25 to match The only time you need a counter is if you re going to mess around with calibrating the PTO and you can set the end points with only the calibrator really got the URM25 so could measure the sensitivity of the radio Works for me but YMMV Date Wed 20 Jun 2001 20 42 41 0700 From Ed Zeranski lt ezeran concentric net gt Subject Re R 390 Thanks and Restoration Update I m jumping in here kind of down the line but have a URM 25F bought ata swapmeet then fixed modulation BS and used them in the Navy back in the 60s Also have have a swapmeet 606 The 25 is a very workable box but the attenuator etc is nowhere near the HP 606 Friend and retired co worker Doug WA6VOV
606. watt resistors Connect the proper end of one diode to pin 2 and the proper end of the other diode to pin 3 and join the other two ends of the diodes Connect the joined ends of the diodes to pins 1 and 4 via a 10 ohm resistor to each of the pins all mounted in an old tube base He claimed this worked exactly like the 83 in the number of Hickok testers he had tried The two 10 ohm resistors are in series across pins 1 and 4 the filament pins and their midpoint goes to the joined ends of the two diodes Without looking at a tube tester schematic I m not sure exactly why the two resistors are wired this way but it works think tried the wiring in one of my testers but reverted to the 83 when found one If the hookup isn t clear from my description can scan a diagram he included to clarify Dan Schematic of 83 substitute Heater Voltage Heater voltage variations can cause unsuspected problems tubes that test good initially but slowly drop with time or tubes thar test ok when sold but are apparently weak when checked on the buyers machine A tube tester transformer is usually wound to give slightly more than nominal heater voltage say 6 6 W from the 6 3 V tap but there can be considerable drop in the internal wiri ng and switches particularly for high current tubes 6 3 V can easily drop to 5 5 or even less 2 5 V for a type 45 can drop to 2 Some TV 7 own ers have reported 1 1 V at the 1 5 V setting causing all battery t
607. we sell the surplus like that for scrap by the Ib guess that was too much trouble Gee IBM had money problems wonder why l Il bet the shipping charges on the old Teks will be more than the scope costs At Dayton there were a couple of guys selling tons of equipment and they still had most of it on the last day Don t think the average test gear page 21 guy is too interested in the old test equipment as compared to all the new wizz bang DSP radios There is a surplus dealer near here that has a couple of our old Tek room heaters with the manuals etc Even has the department stickers on em no charge ha ha But at 300 he s had them for years l doubt if he paid much for them have a Tek 466 and it s small size makes it handy call it a lugable not a portable One of the guys here just got a Fluke handheld scope meter pretty cool Date Wed 3 Jan 2001 15 01 03 US Eastern From n1udi19 idt net Subject Re R 390 R 390A Manuals and O Scope In reference to your question If you are looking for or want to invest in a Tektronics May recommend the Tektronics model 453 It s the last of there tube scopes but a real work horse Mine has been with me over 20 years have 3 Tekies model 502 and 555 The 453 is my favorite the screen is small and square so that might be a problem if your looking for a big round screen Date Wed 3 Jan 2001 15 40 53 0500 EST From Paul H Anderson lt p
608. well as the tuning peaks Date Tue 26 May 2009 08 27 28 0500 From mikea lt mikea mikea ath cx gt Subject Re R 390 HP410B Intermittent s I d totally forgot that part of the movie Now have to get coffee out of the keyboard on the other computer And send my pants to the cleaners Folks here may be interested to know that the USAF and presumably other services had a 300 Baud modem with mechanical resonators back in the late 1960s It had glowbugs too as well as a regrettable habit of ceasing to produce tones When it stopped whistling then it was time to whack it LHARD_ on the lower right corner of the front panel to restart the resonators with a mechanical shock We replaced that critter but nowhere near soon enough for me with a Rixon SeBit 24 that was about the size of a paperback book lots smaller than the 6 rack units that modem ate and lots cooler too Date Fri 29 May 2009 11 49 43 0400 From Barry lt n4buq knology net gt Subject R 390 Parts Request Anyone know where can get one or two 10k wirewound linear taper 2W pot preferably with screwdriver adjust My HP 606A ate one last night I d like test gear page 197 one similar to what s in there but may end up having to go with a multi turn pot if there s room for it Still no luck with a probe for an HP410C either but a question about that one If use a silicon diode for a probe to at least get low frequence AC measurements going tempo
609. wever that the connection from the high level output to the counter and then inside the counter can will leak a lot of signal so if you are doing low level sensitivity measurements do not use the high level output and cap it off With even moderate leakage it s possible to measure receiver sensitivities that are unbelievably low Leaked signal travels from the high level output and wire and counter to the receiver input and adds to the very low signal from the generator attenuator From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 Signal Amplifier Needed Date Mon 22 Mar 2004 15 11 44 0600 Don t have a URM 25 This is the General Radio GR1001A It currently has a plug in the hi output connection Shhhhhh Don t tell anyone how get those great sensitivity measurements From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 Signal Amplifier Needed Date Mon 22 Mar 2004 15 19 45 0600 A quick look at the schematic for the GR1001A reveals the 2V output is not on all the time however it is much easier to switch to it to get the counter s reading and then back to the attenuated output for the real signal A lot easier than building an amp Date Mon 19 Apr 2004 09 54 50 0400 From Roy Morgan lt roy morgan nist gov gt Subject Re R 390 O T page for TV 7 tester gt need a scan or a copy of page 65 66 for the TV 7 D tube tester test gear page 103 The whole
610. witch and applied DeOxit to the contacts while avoiding getting any of it on the ceramic wafers pretty tough to do among those layers and layers Tester now works fine and switch turns more smoothly Date Sun 30 Sep 2001 12 12 49 0400 From Bob Camp lt bob cq nu gt Subject Re R 390 R390A tube chart amp PUZZLEMENT The downside of the 6CB6 is that it does not quite match the gain and AGC characteristics of the 6DC6 As with all subs the capacitance will be different and if you swap tubes you will need to re align the radio The shorts are a bit of a puzzle would bet on the TV 7 rather than on a whole bunch of tubes going bad but it would only be a bet It is possible that the radio got dropped in shipping or something like that If so you could have a significant number of tubes messed up Do you have any idea if the radio worked before you checked the tubes If it worked then they are not shorted test gear page 60 am not to surprised about the weak 6C4 s They seem to go soft but the radio still works suspect that they didn t get checked to often in normal service replace them but often the radio works the same before and after the swap think I d spend some time getting the TV 7 to the point you trust it The other option of course would be to eBay it and get another one Date Sun 30 Sep 2001 12 47 15 0400 From Barry Hauser lt barry hausernet com gt Subject Re R 390 R390A tube chart amp PUZZL
611. witch back and forth and also retested both good and bad tubes same result also allowed the TV7 to cool down for about an hour before retested no difference gt gt The test is like a leakage test so some number of ohms should trigger it gt However don t think it s a very high number would expect to have gt trouble on other test first if the problem was leakage of some sort test gear page 61 The idea is to do the shorts test before quality The possibility exists that quality testing a shorted tube will damage the tube tester At least most tube tester instructions say not to proceed to the quality test if the tube shows shorts If the short is an inside job i e fault of the tester then it may or may not be the equivalent of having a shorted tube in there as far as risk of damage is concerned Can anybody shed more light on this Still possible that as Bob says it s a matter of ohms so some dirt on the switch or maybe ferrite beads too close together is causing an interaction with some tubes Otherwise have a bad run of tubes guess have other tube testers I ll have to dig one out for another opinion Date Mon 01 Oct 2001 12 29 29 0400 From Barry Hauser lt barry hausernet com gt Subject Re R 390 R390A tube chart amp PUZZLEMENT gt Use socket savers if you can find them AES may have them A VERY good idea Thanks Roy but this tester already has em for the 7 9 pin and Octal socke
612. with much higher impedances and prices And there s the HP VTVM test gear page 44 Date Sat 20 May 2000 02 59 59 0500 From Dr Gerald N Johnson lt geraldj ames net gt Subject Re R 390 Instruments First audio plate voltage though 100K resistor A 250 volt scale on a VOM like a Simpson 260 will be 250 20k 5 megohms At 150 volts the VOM will draw 30 microamps and through the 100K resistor that will be an additional 3 volts drop Probably not significant Output stage grid voltage should be about zero across 470K Leakage could raise it Say it was raised 3 volts from capacitor leakage That would be a current of 6 microamps the 5 volt DC range of a VOM similar to a 260 would have a resistance of 100K That would make the equivalent resistance at the grid 470K 100K or 82 45K and that leakage current of 6 microamps would be hidden by showing only 5 volt on the VOM The VTVM would show 2 87 volts So the VTVM would show the leakage as significant while the VOM would make it look insignificant A VOM could load down the oscillator grid test points and make them look defective when the VTVM would say they are not It all depends on the relative circuit and volt meter resistances If you can do a rapid circuit analysis you can correct the VTVM indications for the indications of the VOM Some digital multimeters are confused by RF voltages on their DC ranges so might give misleading readings on oscillator grid test points and
613. with my red one hi These meters do root out bad capacitors quickly too have NO connection with these folks but the price is the same as paid years ago and it has even been improved Date Wed 7 Mar 2012 11 28 29 0800 From Pete Lancashire lt pete petelancashire com gt Subject Re R 390 Capacitor tester The LC 100 s are to me the final eveolution of the high er voltage cap testers Don t have one yet but will someday but having a TO 6A it would have to show up really cheap BTW can t remember the URL but TO do have failure modes and should them selves be restored be using Ditto for Eico 950B s In all most all cases replace the caps R 390A s SP 600 AN XXX etc to me is worth the test gear page 398 time and effort But if is is for something of much less value or a cheap BCB set or some weird value and not enough room to parallel up use a Sprague TO 6A or my ZM 11 U Date Wed 7 Mar 2012 14 37 51 0800 From David Wise lt David_Wise Phoenix com gt Subject Re R 390 Capacitor tester I d add that they should be checked when hot Leakage goes up fast with increasing temperature It may look okay cold After got my 390A decided to replace all of the Prokars Brown Beauties that were a highly charged or b at high impedance points left the cathode bypasses alone Just for fun hooked the IF deck to a current limited power supply B only put it in the oven on low and left it overn
614. with the audio out function test gear page 96 From JamesMiller lt jmiller1 706 cfl rr com gt Subject Re R 390 8640 was Deoxit Date Sun 30 Nov 2003 12 27 08 0500 Well must have had a brain slip tried it and yes 447 khz Wouldnt you know The manual says 500 khz is the low limit and never bothered to try it lower in the over coverage region Thanks guys Date Sun 30 Nov 2003 12 32 39 0500 From James M Walker lt chejmw acsu buffalo edu gt Subject Re R 390 Deoxit Sorry for the repeat Also note the operators manual and also the service manuals are on the ETM LOGSA site full manuals in PDF and free Date Sun 30 Nov 2003 09 33 49 0800 From Dan Arney lt hankarn pacbell net gt Subject Re R 390 Deoxit The spec s say minus 10 on the low side and plus 5 on the high end Date Sun 07 Dec 2003 08 36 01 0500 From Michael Drum lt mjdrum comcast net gt Subject Re R 390 Signal Generators was Deoxit wanted a 8640B years ago but it was over my head price wize just found one on the auction place for 150 using the buy it now option It is in working shape and looks to be in good cosmetic condition as well don t think I m ever going to get one cheaper then that Beware of a seller offering a manual download for the 8640B It s available as a free download from the BAMA web site This guy is trying to profit from other peoples work told him he was selling Copyrighted work and he
615. with the exception of the I m not sure about the URM 25B and URM 25C models since don t have manuals for them but I ve been told that they also had a 53 5 ohm output rather than 50 ohms like the later models Date Sun 09 Jan 2000 16 46 56 0600 From Dr Gerald N Johnson P E lt geraldj ames net gt Subject Re R 390 Signal generator connection questions gt As much as one of these leaks why can t you just put the included antenna on the freq counter and read the leakage You sometimes can but you don t gain anything in controlling the signal to the receiver because the internal signal level in the counter is still a few volts peak to peak to run the logic You can sometimes detect when the logic is counting the gate is open by the increase in signal radiated from the counter gt Also how does one set the frequency of the URM 25 D gt to 455 Hz exactly without a freq counter You have to interpolate from the crystal markers built in or else with an external frequency standard like an LM frequency meter or BC 221 or by beating against an external 455 KHz crystal oscillator These days the most convenient thing to do is to let the signal generator warm up a lot to stop drifting connect the cable to the counter to set it to 455 then unhook the cable at the generator end and cover the connector You can also get a calibration point at 450 KHz probably by using a harmonic though it will be weaker Once upon a time
616. wn in the innards have to be replaced The ID Tag has this printed on it Trad STANDARD SIGNAL GENERATOR MODEL SG 25 SERIAL NO 544 TRAD ELECTRONICS CORP ASBURY PARK N J 2 From what can find out this is civilian version of the AN URM 25 version C D don t know 3 Is there a WWW site with URM 25 history 4 The front panel is not painted The aluminium finish appears to be either a silver anodize or a clear chemical film Similar to araldite would like to refinish the panel Either redo in the original finish or paint test gear page 104 5 The case is painted grey about the same colour as the URM 25F It is stencilled with AN URM 25 D Is this the norm 6 The signal Generator came with these accessories 1 IMPEDANCE ADAPTOR MX 1487 URM 25D 2 IMPEDANCE ADAPTOR MX 1487 URM 25D PART OF AN URM 25H 3 TEST LEAD CX 1363 U PART OF AN URM 25H 4 ANTENNA SIMULATOR SM 35 URM 25D PART OF AN URM 25H 5 CG 409 U 0 5 Have 2 of these They are original with the aluminium cable marker RG 58C U coax Comments and advice on any repair or refurbishment would be appreciated also need information on the reliability of paper caps in the metal tube with the one end soldered to the case for the ground connection have requested in with W J Ford Surplus here in Canada to rent for thirty days a manual If can t get one and any one out there needs any of the extra accessories maybe a trade could be arranged or trade fo
617. worked at the time found later that they both worked fine Kept one swapped the other to a friend Never used one of these before am extremely pleased with it Set bandwidth desired down to 50 Hz choose mode AM CW USB LSB tune it across the freq range of interest bandswitched in 1 mHz increments using its built in LED digital counter find the peak on the meter and viola a direct reading freq counter VT VM all mode receiver w precision step attenuator in volts or dbm down to 110 dbm It has a full receiver chain w audio stage built in plug in a set of phones and an antenna and listen directly to the ham bands up to 18 mHz but seems less sensitive at the far end of the pipe than a normal receiver suppose mainly because of minimal IF stages included It is within 20 Hz of my HP 5328A counter in freq accuracy extremely stable moves less than 50 Hz in 24 hrs from a cold start and is built in the famous HP engineering overkill manner This thing works great for verifying inputs and outputs of a mixer stage etc It should also be great for measuring filter bandpasses although it does NOT have a tracking generator built in so your sig gen hand cranked becomes the manual tracking generator for sweeping a filter stage Now that I ve used it don t know how got along without one all these years Drawbacks About the size of an R 390 although about 1 3 the weight And God help me if it ever craps out On the other hand it s ru
618. worry of a failed blocking cap or something similar failing and allowing B from either the receiver or signal generator to feed into the counter and puke it haven t had very good luck with counters and leave them connected to whatever I m messing with as little as possible gt By the way perhaps we should agree on the setup gt to measure the sensitivity of the R 390 so we can better compare gt who has the hottest receiver noticed that I ve been measuring gt as if the radio had a 50 ohm input and should have been shunting gt the input with 100 ohms or so to comply with the URM 25 manual Actually other than for the sensitivity measurement of the R390A the standard adapters that come with the URM 25D are more than enough to align the receiver test gear page 289 It s simple enough to build one of the DA 121 U 50 to 120 ohm impedance matching adapters built mine in an extra can from a URM 25F that someone sent me I ve built the regular adapters before for a friend out of copper water pipe and end caps They worked like a charm and were probably better shielded than the originals Here s a rough schematic of the 50 to 120 ohm DA 121 U adapter to URM 25 to R390A 50 ohms 120 ohms gt NN lt J1 R1 J2 lt gt R2 lt gt gt lt R1 is a 100 ohm 1 4 watt resistor R2 is a 68 ohm 1 4 watt resistor J1 and J2 are male BNC connectors Dat
619. xed measured the grid voltage at the test point and lo and behold instead of measuring 100mV it measured close to 6V Since hadn t calibrated the meter this reading was just a ballpark figure While holding the VTVM on the test point stuck the DMM at the same point and the voltage dropped to about 100mV This didn t surprise me as would expect the DMM to load the circuit down What DID surprise me though was when stuck the VTVM and TEK probe at the same test point the voltage dropped the same way as it did with the VTVM and the DMM Is this normal thought the TEK would not load a circuit like a DMM Is there something wrong with the TEK I ve been making these voltage measurements with it all this time and assumed it wasn t lying to me however apparently the HP proved me wrong checked the accuracy of the VTVM and it is pretty far off My 13 8VDC supply checked 11V on the 30 and 100 volt scales This tells me the 6V was getting at the test point is really closer to 7 5V which depending on the crystal selected is in tolerance not sure about that It s been a long time since used an analog meter and the HP is really nice It makes me realize just how convenient it will be to peak the various circuits when align my radio Really smooth movement test gear page 47 Date Mon 22 May 2000 10 52 17 0400 From Roy Morgan lt roy morgan nist gov gt Subject RE R 390 Instruments Both the DMM and the Tek prob
620. y accurate i e the URM meter says one thing and the HP says another Sure would like to get this URM25 right before button it up in a month or so yes I m slow Date Sat 08 Jan 2000 08 09 13 0600 From John P Watkins lt jwatkin9 idt net gt Subject Re R 390 HP 8640B questions Hi All have the Mil 8640B USM 323 and it will go down past 455Khz just fine was wordering if anyone out there has the schematic for the non mil 8640B counter assembly The non mil units have a 7 digit display and can also be used as a freq counter My mil model has a 6 digit display and and no outside input After looking into it looks as if all that needs to be done is provide a relay with SMA connectors and an attenuator to provide the extra input By the way these are great sig gens John WD5SENU es Date Sat 8 Jan 2000 15 34 42 0000 From Bill Coleman lt n2bc stny rr com gt Subject R 390 Signal generator discussion All the interesting chatter about signal generators has prompted this A couple years ago spotted a PC based generator look here http www bytemark com A nifty gadget DC to 54 Mc with resolution to less than 1 cycle pls notice the boatanchor appropriate units For years have used a General Radio 1001 A combined with a freq counter Now have a dedicated PC in the shop with the PC VFO and full of all of my other assorted radio related software run the PC VFO s output through a 0 to 80 dB attenuator whi
621. y one have seen has tan cased MicaMold oil filled capacitors and at least one of those is leaking oil Some of them are tough to get to but every one should be removed and replaced like the yellow wraps available from AES for replacements Personally would never convert any tube rectifier power supply to solid state if only for aesthetic reasons Tube rectifier power supplies come up gently If you test gear page 347 convert to solid state every time you turn your gear on is like hitting it with a big hammer And anyway what is the point of removing tubes from tube gear Too cheap to buy the appropriate rectifier tubes If we are going to remove the rectifier tubes let s remove all the tubes And then why buy tube gear and convert it Let s just buy stuff that is already all solid state And electrolytics dare bring up that topic again think not because the doctor is probably lurking and am not in the mood right now for a tussle But here is a war story don t think anyone can object to A European friend of mine sent me his Telefunken E 1501 to fix While fixing it noticed that the power supply was quite noisy loud mechanical hum The E 1501 is modular so removed the power supply module to give it a look see While was examining the power supply noticed that a previous owner replaced two of the electrolytics in a misguided attempt to reduce the mechanical hum Why have concluded this Because the zi
622. y really are RG 58 In the mean time the clients think should show them new products None of the dummy loads in Nolan s posting match the MS 1487 A schematic in my URM 25D manual or what found in the CV 206 URM 25F that opened up for inspection Date Fri 27 Oct 2000 15 43 09 0500 From Scott Barry Clyde B lt cbscott ingr com gt Subject RE R 390 MX 1487 Adapter wonder if the velocity factor of CG 409 U comes into play here As said the technical bulletin shows very specific lengths for these cables Date Fri 27 Oct 2000 16 22 48 0500 From Dr Gerald N Johnson electrical engineer lt geraldj ames net gt Subject Re R 390 MX 1487 Adapter A short very mismatched cable at VHF looks more like a lumped capacitor especially when the load is high impedance So the distributed C is important the rest is not 150 ohm coax is hard to make Date Fri 27 Oct 2000 22 27 23 0400 From twleiper juno com Subject Re R 390 MX 1487 Adapter gt wonder if the velocity factor of CG 409 U comes into play here As test gear page 20 gt said the technical bulletin shows very specific lengths for these cables gt Barry N4BUQ Well whatever the V Factor it certainly would be off after all these years and can t imagine putting a tuned element into the equation suspect it is just the military way a spec for everything In this case the length that will properly stow It also prevents the mili
623. you ll need an LM317HV There may be newer parts that are better but the LM317 should work and is readily available The 317HV might be hard to find gt Also would like to make a 1 5V power supply for the D cell but not sure if a 1 gt or 1 5 xfmr could be had as well as whether a 1 5V regulator is available The LM317 will go down to 1 5 volts Date Mon 17 Sep 2007 14 36 18 0400 From wabate lt wabate verizon net gt Subject Re R 390 OT 30V regulator have a Triplett as well but a different model The 30V battery is tough for me to get So I installed 4 nine volt batteries in series They last forever The point is that you don t have to regulate the power supply if you want to build one It isn t that fussy Why complicate it Date Mon 17 Sep 2007 14 44 35 0400 From Barry lt n4buq knology net gt Subject Re R 390 OT 30V regulator You might look here http www batteriesinaflash com index php main_page product_info amp product s_id 1495 Believe it or not Radio Shack can order the Eveready 30V battery for you and have it shipped to your house for no shipping charges was just trying to come up with something that doesn t use batteries always have that fear of them leaking etc do like the 4 x 9V solution though finally found the schematic and see where the 30V is only needed on the highest ohm scale so might not even fool with it Date Mon 17 Sep 2007 14 48 10 0400 From Roger Gibboni
624. your results nolan Date Sat 10 Feb 2001 08 40 27 0800 From keith lt khgrant ix netcom com gt Subject Re R 390 Bathtub capacitor replacement Good description Sounds kind of messy How do you measure leakage on this bathtub cap Date Sun 11 Feb 2001 05 57 23 EST From G4GJL aol com Subject Re R 390 Bathtub capacitor replacement used to use the leakage position on my transformer ratio arm bridge But that only tests at 10 v or so have adopted Dr Jerrys method of using a varivolt bench PSU and a 100Mohm input impedance VTVM As a series circuit it is described below Output of PSU goes to first wire of C under test Other end of C goes to VTVM input HIGH VTVM LOW strapped to ground Ground returned to PSU negative PSU negative strapped to Ground Your acceptance of what is or is not leakage will vary but with Polyester tubulars that use can only see the residual noise when the cap has stored its charge this is at about 10 to 15mV for 0 01 uF 400v rated Vishay Roederstein Poly tubulars at 1 5 times the rated voltage applied Almost all BA caps are so leaky you cannot get down to these levels you will see to PSU voltage build up across the C before you get any where near to the cap retaining a charge Date Sun 18 Feb 2001 14 47 19 0600 From Nolan Lee lt nlee gs verio net gt Subject R 390 TV 3 amp TV 10 settings project starts test gear page 50 have an affordable and working TV 10
625. ything but you can fix it gt was checking the voltage on a UPS when my Steel Six meter decided to crap out Not good liked that meter Many meters have this problem gt It seems to have either demagnetized the magnet or magnetized the vane not gt sure which The coils are OK because when reverse the probes the needle is gt drawn below zero it just won t go above about 2 volts on a 50 volt scale Nope the problem is likely a very small iron fragment that is jamming the mechanism gt If there was an AC component on the DC was measuring would it have done gt this The charger was on was trying to determine if the batteries were gt charging Nope Here is how you return the meter to service 1 take the meter apart exposing the mechanism 2 prepare very thin strips 1 16 of regular Cellophane tape 3 With stainless steel tweasers or some other tool run the thin strips along the armature and between the magnet and the meter windings Metal particles will stick to the adhesive on the tape Examine the strips If there is the slightest fragment on the strip replace it with a new strip and continue until the strips come out clean Change strips often for particles can be rubbed off the strips can re contaminate the meter movement This operation is best done test gear page 87 under a magnifing glass Be careful not to damage the spring or you may really lose the meter 4 Gently blow across the me

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