Alpha 8410 User Manual (2009)
Contents
1. e Oe ee gt OT SJ gt x w Oua 27 7 Poorly designed consoles can result in outlet air being drawn back into the amplifier air intake and recirculated thus getting hotter and hotter and resulting in degraded amplifier performance or even failure If you are designing your own console consider putting in additional fans and or ducting to deal with waste heat Try to minimize the possibility of dust or other contamination getting drawn into or falling on the amplifier It is also advisable to periodically at least annually clean the dust out of your amplifier for continued flawless operation Alpha Radio Products recommends the use of compressed air for dust removal 3 4 Antennas Many antennas that are suitable for general use are unsuited for operation with a full 12 1500 W of power At this power level in a 50 ohm circuit the RMS current is 5 5 amps and the peak RF voltage is 387 volts With a 2 1 SWR these values double to 11 amps and 775 volts The actual voltage and current at various points in or on your antenna may actually be many times these values On a simple dipole with sharp wire ends corona localized ionization can easily occur Corona can and has led to fire in nearby objects Traps in beams and verticals can heat up significantly during high power operation Instances of melting or flashover of traps have occurred in many installations where insufficient thought has been given to their rat2. 0 77 a a ee 8 58 Aa EI Sa er 80 56 53 xtach ALPHA 8410 shipped from our factory will include an individual table showing the tune and load settings we used to achieve full output power on that amplifier into an AP 2100 a 50 ohm dummy load These settings usually vary slightly from those in the manual CAUTION If at any time in the following procedure the amplifier fails to respond as described remove drive immediately and turn the OPR STBY switch to STBY Verify all connections and cables turn the amplifier switch to OPR and proceed with the tuning procedure 32 Alpha Radio Products recommended tune up procedure Dip and Load Method Tuning up for Operation at 1 500 W RF Output Preset BAND TUNE and LOAD controls to the nominal positions given in your amp s specific tune up table or Table 6 3 Note Final TUNE and LOAD settings will vary with the operating frequency antenna characteristics and power level 1 Please limit the transceiver drive to about 65W for tuning up and operating the amp Set multimeter to Ip Plate Current Set TUNE and LOAD controls to numbers indicated in the tune up sheet originally included with the amplifier Key radio with 20W drive and adjust TUNE control for a peak in RF out which should be at the same point as a dip in Ip Increase drive to get 1000W output going back and forth between the TUNE and LOAD to peak the RF output If more outp
3. must exit only through the tube anode fins it must not be allowed to escape outside them Failure to ensure proper cooling airflow may result in tube damage or destruction which is not covered under warranty 4 2 2 Connecting the Transformer Power Plugs Connect the 9 pin white Molex connector to the matching plug mounted on the back wall of the amplifier Connect the 8 pin orange connector to the matching pins on the upper Mains PCB Connect the 6 pin yellow connector to the matching pins on the lower HV PCB Check to ensure that all connector pins on these three connectors engage fully and correctly 4 2 3 Power Cord Connections WARNING To avoid the hazard of a potentially fatal electric shock and or Severe damage to the ALPHA 8410 and other equipment always use an AC plug that is appropriate for the primary mains voltage current rating and configuration NEVER use 120V type plugs and power receptacles for 190 250V circuits ALWAYS use grounding type AC connectors which conform to local codes and ensure that the green wire in the Alpha 8410 power cable is wired only to the AC mains safety ground or to neutral as may be necessary with a 240V circuit configured 120V N 120V without a separate ground commonly found in the US The green conductor in the power cord is wired to the ALPHA 8410 chassis It MUST be connected only to the power source safety ground or neutral The black and white power cord wires connec
4. RF decoupling circuit on the B line as well as the crowbar safety circuit This safety device consists of a piece of spring metal which shorts out the B line when the top cover of the amplifier is removed Do not defeat this safety circuit It is placed there for your protection 26 6 Operation amp Maintenance The ALPHA 8410 is extremely easy to operate but failure to carry out each procedure exactly as described in this manual is likely to lead to amplifier damage which is not covered under warranty Damage to other station equipment may also result 6 1 Before Operating Your Alpha 8410 6 1 1 Setting Input Drive You must set the transceiver output power properly Virtually all damage to has resulted directly from severe overdrive The ALPHA 8410 requires about 50 W drive for full rated output Damage caused by applying several times rated drive power to the ALPHA 8410 will not be covered under warranty Fortunately most modern transceivers maintain quite consistent output from band to band and mode to mode when set up properly CAUTION Setting only the transceiver POWER or RF PWR control IS NOT SUFFICIENT Several popular transceivers can generate AF spikes of 200 300 W Control of these spikes typically is done with a knob labeled DRIVE IC 781 FT 1000 or PROCESSOR OUT TS 940 TS 950 On SSB when speech processing is not used adjust the MIC or MIKE controls See the operator s manual for your particular transc
5. be able to get 1 500 watts output if your line voltage is below 120 volts If your line voltage is between 110 and 130 volts then 1 500 watts PEP operation CW or SSB may be possible if your AC line service has sufficient current capacity 30 amp circuit recommended However 1 500 watts continuous should not be expected If your line voltage is between 90 120 volts then power outputs above 1 000 watts should not be expected from the amplifier Tune adjust the amplifier for no more than 1 000 watts output and simultaneously for maximum efficiency placed where normal air flow is restricted because the cord could overheat If other equipment is drawing current from the same circuit as the Alpha 8410 then the considerations in section 4 2 3 should be taken into account High Voltage and Tube Life At the high end sometimes encountered when using poorly regulated generators the plate voltage and tube heater voltage may be too high If voltages above 250 volts are applied for any length of time the lifetime of the tubes may be reduced If this is your situation the first line of defense is to contact your utility 1 company and ask if they can reduce your line voltage If this is not possible you may want to consider placing your own step down transformer in line between the AC outlet and the amplifier If this is necessary a transformer with at least 4 kVA rating is required due to the nature of the current waveform in the primary Anothe
6. cable or other shielded and grounded unshielded station patch cables 4 Poor station RF ground Be sure the amplifier and transceiver have a proper RF ground Correct if necessary Required drive to maintain 1 500 W is steadily increasing 41 Problem Correction 1 If the amount of drive required to maintain 1 500 watts is steadily increasing this is an tubes need replacing indication that the tubes are probably aging Contact Alpha Customer Support to see if 42 8 Glossary The following terms are used in this manual Detailed explanations may be found in various publications including the ARRL Handbook AB1 Modulation class ABl Provides good linearity in push pull configuration AC Alternating current ALC Automatic Level Control ampere Current measurement ARRL American Radio Relay League AWG American Wire Gauge CW Continuous wave dB Decibel EBS Electronic bias switching Exciter The radio that provides RF drive for the 8410 to operate FCC Federal Communications Commission FM Frequency modulation FSK Frequency shift keying HF High frequency 3 to 30 MHz HV High voltage Hz Hertz Ip Idling plate current kV Kilovolts kVA Kilovolts ampere kVA 0 8 kilowatts kW Kilowatt LED Light emitting diode LV Low voltage mA milliAmpere MH2z Megahertz OPR Operate PSK Phase shift keying A digital modulation scheme QSK Quick shift keying In this CW transmitting mode the transmitter is o
7. start fuses will normally blow CAUTION DAMAGE RESULTING FROM USE OF A FUSE OF INCORRECT SIZE OR TYPE WILL NOT BE COVERED UNDER WARRANTY AND MAY VOID THE WARRANTY 6 4 4 Plate Over Current Relay This relay will quickly turn off the amplifier in the event of grossly excessive plate current or fault in the high voltage circuitry The relay will not prevent tube or other damage due to either short or long term overdrive or improper tuning It is the operator s responsibility to ensure safe tuning drive and general operating conditions Should the over current relay trip remove AC power from the amplifier then determine and correct the cause of the trip before turning the 8410 on again This hard fault trip circuit does not rely on the microcontroller for it s operation and will protect the amplifier even if the processor has been damaged or is malfunctioning 6 4 5 Idling Plate Current and Electronic Bias Control EBS Idling plate current of the ALPHA 8410 is approximately 350 to 400 mA during full power transmission A detector senses RF drive and reduces plate current to 30 50 mA during pauses in speech and key up intervals thus substantially reducing average power supply loading heat generation and wasted energy 6 4 6 RF and Mistuning Protection The ALPHA 8410 s exclusive circuit senses the beginning of any RF arc in for example a TUNE or LOAD variable capacitor and automatically switches the amplifier to standby w
8. way OFF wait at least 20 seconds before turning the amplifier power on again 28 If you are certain that you have taken care of the problem that caused the fault you may turn the amplifier back to operate and proceed with use 6 1 3 High SWR Considerations On any frequency where your antenna VSWR exceeds 1 5 1 it s important to carefully tune the ALPHA 8410 for a proper match The ALPHA 8410 does not contain an antenna tuner The SWR can be tuned via the antenna or an external tuner connected to the output of the Alpha 8410 Nevertheless if the system SWR is below 2 1 the additional RF power loss of an antenna tuner can be avoided by tuning the 8410 into the slight mismatch There is no advantage to using a tuner to tweak the last bit of SWR in fact you will lose power this way 6 1 4 Operating at Less Than 1 5 kW Requires Retuning If you tune the amplifier for maximum power output and then decide to operate the 8410 at a power output much different from 1 5 kW it must be re tuned for efficient and RF clean operation Under such lightly loaded conditions the green grid LED will probably be fully lit Note that if you tune the amplifier at 1 500 watts and then simply reduce power to 1 000 watts the tubes are actually going to run hotter than at 1 500 watts It is better to tune the amplifier with close to 50 watts of power but reduce the loading control to get 1 000 watts 6 1 5 lightning Protection Induced ene
9. ALPHA 8410 HF LINEAR AMPLIFIER OPERATING MANUAL Mg ALPHA 8410 tli r 2009 Alpha Radio Products Inc 6185 Arapahoe Ave Boulder Colorado 80303 Phone 303 4739232 All rights reserved Specifications subject to change without notice Rev 102 EN 17794 ALPHA 8410 3 ei 2 HF LINEAR AMPLIFIER 70 K A LA Ru 8 wr mm 8 Serial Number Date Shipped Software Version Order Number Index Specifications Introduction Quick Start Information Station Engineering Considerations Unpacking and Preparation Theory of Operation Operation and Maintenance Trouble Shooting Hints Glossary 23 27 39 43 Specifications Frequency Input drive Level Power Output SWRA Tolerance Duty Cycle Tubes Inter Modulation Level Harmonics Mode of Operation Input AC Voltage AC Current Input Impedance Output Impedance RF Connectors Cooling Size Space Weight T R Relay Tuning Band switching Display Interface Protection RF Bypass Level 1 8 29 7 KHZ 50 Watts Nominal 1500 watts 3 1 100 o 2H UTH H118 Alpha 4CH1000A 30 dB minimum Two Exciter 50 dBc CW SSB FM 100 240 Selectable lt 13 5mps W240 VAC 1500 watts 50 Ohms 50 Ohms 50 239 Forced Air 17 3 WH HH 21 0 D Including Fan 70 lbs 31 8 kg Vacuum QSK Manual Bargraph LED USB Against all common faults Less than 500 watts This amplifier meets or exceeds all technical specific
10. _ Transformer Installed Section 4 2 1 4 2 2 __ Power Cord Connector Attached Section 4 2 3 __ AC Primary Voltage Set Section 4 3 6 ___ Amplifier Grounded Properly Section 4 4 1 __ Amplifier Cover Replaced and Secured Section 4 3 6 2 5 Operation __ All Exciter Interconnections Set Section 6 2 __ Exciter Drive Correctly Set Section 6 1 1 __ Amplifier Tuned to Antenna System Section 6 3 6 10 3 Station Engineering Considerations 3 1 Overview The Alpha 8410 is capable of dramatically improving the performance of your amateur station It is important that you observe good engineering practices to achieve all the benefits of such a station in a safe and reliable manner This section provides a few hints for important operational considerations but it is recommended that the user also consult a good source of general information such as The Radio Amateur s Handbook by the ARRL especially if this is the first high power amplifier you have used 3 2 AC Power Source This amplifier runs best when powered by a 200V 240V AC circuit If you do not have a 240V AC outlet in your shack you will need to get a licensed electrical contractor to install one A minimum of a 20 amp capacity is required A 20 amp breaker on your 240V circuit is sufficient There are many styles of plugs some of which are country specific For this reason the amplifier is not shipped with a power plug Select a location for the outle
11. anding bias on the tubes resulting in less waste heat longer tube life and higher overall amplifier efficiency The artifacts of EBS are not noticeable under normal communications conditions 5 3 Output Tank Circuit The output tank circuit of the Alpha 8410 is designed to provide reliable high efficiency low distortion performance in a very compact volume The basic topology is pi L which provides harmonic attenuation adequate to meet the requirements of all countries globally that permit power outputs of 1 500 watts Band switching is under manual control and is accomplished by a four wafer band switch These wafers are used as 23 multi function tap selectors which simultaneously select band taps on the inductors and include varying amounts of capacitance to provide band spread on the tune and load capacitors These four wafers are in the RF tank area A variable resistor inside the front sub chassis and is used by the control board to determine which band the user has selected 5 4 Tube Deck The tube deck is a mechanical assembly built around the tube deck PCB The tube deck PCB has the tube sockets mounted on it as well as those critical circuit elements that need to be in close proximity to the tubes The tube sockets contain integral screen grid grid 2 RF bypass capacitors Also on this PCB is the input bypass relay This relay is under microprocessor control and in one position switches the input RF to the tubes and in the
12. ations listed above Technician Date 1 Introduction 1 1 General Description Congratulations on your purchase of a professional quality Alpha 8410 amplifier With proper installation and care you can expect to enjoy your Amateur Radio hobby with this amplifier improving your signal for many years to come Please study this manual carefully before operating your amplifier for the first time The Alpha 8410 is a self contained manual tune HF linear power amplifier capable of continuous operation at 1500 W peak power output on SSB keyed CW SSTV RTTY digital modes or FM with no time limit Other Alpha products available to enhance your use and enjoyment of the 8410 amplifier include e Alpha 2100 full 1500 watt rated 50 ohm dummy loads and e Alpha 4500 series SWR meters Wattmeter See our web site at www alpharadioproducts com or call 303 473 9232 for further information 1 2 Amplifier Capabilities CAUTION It is extremely important to thoroughly review the Installation and Operation sections of this manual before attempting to us the Alpha 8410 Failure to do so could result in serious damage that may not be covered under warranty e Continuous RF Output The 8410 is capable of 1 5 kW continuous RF output on all commonly used modes and on any authorized amateur frequency from 1 8 to 29 7 MHz e Compatibility with popular amateur transceivers and exciters The 8410 requires approximately 50 65 W peak RF drive for 1 5 kW ou
13. citation power until the 8410 output is about 1 500 W Repeat steps 6 and 7 at least twice Touch up the TUNE control for maximum power output The ALPHA 8410 is now correctly tuned to deliver 1 500 W RF output on SSB CW FSK SSTV and FM The TUNE LED normally fluctuates during modulation or keying Illumination of the first red LED on the RF OUTPUT bargraph indicates output has exceeded 1 500 W The tune LED may vary during standard operation especially SSB This is normal 34 6 4 Normal Use 6 4 1 Tubes The VTX X118 tubes used in the Alpha 8410 are supplied as a matched pair They are very rugged and normally operate with a large margin of safety They should provide outstanding service for many years if not damaged by abuse such as overdrive or blockage of cooling airflow Allow at least three to four inches 10 cm of unobstructed clearance around the air intake and exhaust areas Stacking equipment on top of the amplifier is not recommended Never allow key down plate current to exceed 1 5 A for more than one or two seconds If you do and a plate current trip occurs it will automatically reset in about 4 seconds if the amplifier is returned to receive key up Never allow the red GRID LED to stay brightly illuminated for more than a second Frequent on off AC power cycling may shorten the tubes life It is less stressful to leave equipment in standby for several hours than to cycle power repeatedly on off on of
14. e 5 6 Control Board The control board is the heart of the amplifier It is based around a PIC microcontroller This microcontroller has a built in multi channel analog to digital converter which is used to monitor all the critical voltages and currents in the amplifier as well as the input power and output forward and reflected power It uses these converted values to control the amplifier s operation and to drive the display board on the front panel A USB port is provided for remote monitoring and is found on the back of the Alpha 8410 The USB driver for the amplifier is provided on the CD shipped with the unit or can be found on the Alpha website at www alpharadioproducts com 5 7 Display Board The display board uses a MAX7219 LED driver chip It receives data from the controller via an SPI interface It contains a regulator to drop the 12 V to 5 V for the display 5 8 T R Board The T R board contains the input and output relays as well as the input power detection and output directional wattmeter The voltages from the detector are connected to the control board There is a trimmer capacitor on this board that is adjusted with the amplifier operating into a good 50 ohm dummy load The capacitor is rotated to minimize the reflected power voltage The board also has an 800 V protection device on the RF output This is located between the PCB and the flange of the output connector 25 5 9 Center Partition Board This contains the
15. e fuse or breaker may be open reset circuit breaker 2 Amplifier cover is not in place or Make sure cover is replaced and all screws properly secured cover safety interlock is ae securely inserted D 3 Fuse F1 F4 open or missing Check Check and replace any blown fuses with fuses with an ohmmeter fuses of the same size 4 Step start resistor open Check resistor If damaged replace Amplifier turns on but no HV is indicated by the multimeter LED bargraph 1 Multimeter selector switch in wrong Set Multimeter switch to the correct position position e g Ip 2 Possible HV circuit fault es 3 HV sampling resistor in power supply damaged Check power supply wiring and connectors 4 Transformer plugged into power supply to be sure input and output connectors are set incorrectly properly and the voltage taps have been set properly 39 Amplifier turns on but no multimeter indication other LED bargraphs are operative 1 Low voltage power supply problem PO 2 Defect or damage on control board CC O O Amplifier turns on but time delay will not complete WAIT LED does not turn off Problem Correction 1 Defect or damage in timing circuitry on Contact Alpha Customer Service control board Amplifier turns on time delay completes but amplifier will not transmit Problem Correction 1 Open T R control line from transceiver to Contact Alpha Customer Service RELAY jack Amplif
16. e transformer and the front panel There is a row of 5 fast on connectors J1 through J5 and a flying jumper connector which mates with them See Figure 4 3 above There are 5 nominal primary voltages which cover all the line voltages normally encountered around the world Selecting the appropriate tap for your situation will optimize amplifier performance safety and lifetime The nominal mid range voltage for each tap is printed on the Mains Board circuit board These voltages are 100 120 200 220 and 240 Volts The acceptable line voltage for each tap is the center voltage plus or minus 10 Volts One of these taps is suitable for any of the nominal line voltages encountered worldwide CAUTION When using any high power amplifier failure to connect ALL station equipment to a good common ground may allow Af feedback to leak into the transceiver and cause severe signal distortion 20 4 4 2 Replacing the Amplifier Cover Replace all attachment screws Use only the 6 32 screws supplied with the amplifier and do not tighten any of the screws until all are started Do not attempt to operate the amplifier with the cover removed or only placed back on the unit without the attachment screws This WILL cause damage to the Alpha 8410 and may also lead to injury or death to the operator 4 5 Amplifier Station Interconnections Once the power transformer is installed properly configured and the cover replaced place the amp
17. eiver 6 1 2 Dealing with Faults The ALPHA 8410 faults into STBY or OFF when unsafe operating conditions occur This is shown when the amplifier changes from the OPR LED being ON to the Fault and STBY LED s If the 8410 encounters unsafe operating conditions it enters a protective Fault mode When this happens the tubes are biased off and the relays are placed in the bypass mode so that RF from the radio goes directly to the antenna The FAULT LED on the front panel will flash on and off for a period of about 4 seconds after which the amplifier will attempt to go back into OPERATE mode unless the 27 OPER STBY switch has been placed in the STBY position This 4 second period can be shortened by toggling the OPER STBY switch While the FAULT LED is flashing the Ip and HV LED s are used to indicate which of the four fault conditions caused the amplifier to enter fault mode Fault type 1 Neither Ip nor HV LED s are lit Output relay did not close This fault will rarely be encountered but if it is it must be investigated further immediately as continued operation with this fault could cause additional damage to the amplifier Fault type 2 Ip LED is blinking This indicates that the plate current in the tubes exceeded 1 5 amps This could be caused by the amplifier being mistuned or by overdriving the amplifier If neither of the above is the case then a problem in the bias control circuitry may be indicated Faul
18. en GRID 30 LED will flicker on SSB voice peaks and illuminate under CW SSTV RTTY carrier conditions As overdrive approaches grid current increases rapidly and the red GRID MAX LED illuminates At maximum output and efficiency the red LED lights dimly full illumination of the red LED indicates overdrive and must be avoided If the red LED lights up before the desired value of plate current and or against grid current fluctuations On SSB optimum output consistent with good linearity occurs when the green forward LED s illuminates on most voice peaks and the red LED flickers dimly on only the highest peaks Excessive grid current results from overdrive and or inadequate loading The solution is to restrict drive and or increase amplifier loading The 8410 s VTX X118 tubes are well protected and these adjustments tend to be less critical than in many other amplifiers Grid bias is stabilized against grid current fluctuations 6 3 4 ALC The 8410 grid current limiting circuits provide substantial tube protection against possible damage therefore no ALC control is necessary It is only necessary to set the drive power from the radio as detailed in this manual 6 3 5 Turning On The Amplifier Please Note Every time the ALPHA 8410 is powered up there is a built in 180 second warm up wait 1 Place the OPR STBY switch to STBY standby 2 Rotate the multimeter selector switch to HV 3 Depress the POWER ON switch The fan and blo
19. f over the same period 6 4 2 Interlocks The ALPHA 8410 is equipped with a cover interlock switch intended to remove primary power from the amplifier and a crowbar to short circuit the high voltage to chassis whenever the cover is lifted These interlocks are designed to protect against dangerous electric shock resulting from accidental contact with the lethal voltages inside the amplifier WARNING ALWAYS DISCONNECT THE AC LINE CORD FROM THE POWER SOURCE BEFORE REMOVING THE TOP COVER FROM THE 8410 FOR ANY REASON Cover interlocks are intended only as back up protection against accidents Never depend on them Always disconnect the power cord from the AC mains before removing the cover Interlock switches should not be disabled for any reason 39 6 4 3 Fuses Never replace any fuse with one of a different type or greater current rating Blowing of one or both primary line fuses indicates that the maximum safe average power capability of the amplifier has been substantially exceeded or that an equipment failure has occurred USE ONLY 20 AMP 250 VOLT RATED FUSES for 190 220 VAC service 25 amp fuses may be used with caution for line voltages of 90 130 V The slow blow fuses Fe located below the primary line fuses may prevent damage to the stop start resistors and HV rectifiers in the event of abnormal turn on conditions or HV faults If the AC interlock is defeated and primary power is applied while the HV crowbar is close the step
20. for disconnection of the feed line when it is not in use this protects against damage caused by power surges and lightning strikes which are not covered under the amplifier warranty 3 6 RF Safety The FCC requires users to check their installations for compliance with published values for allowable exposure to RF fields This information is available in ARRL publications FCC printed rules and on the web Alpha Radio Products strongly recommends that this be done for any installation both fixed and at an expedition or contest site 13 If you have any questions regarding engineering your 8410 into your amateur radio station please visit our online technical support website at www alpharadioproducts com 14 4 Unpacking amp Preparation 4 1 Unpacking Remove the strap securing the two boxes to the pallet Inspect both boxes for physical damage Save all packing material and pallet for possible future use Contact 303 473 9232 if shipping damage is found Carefully unpack the amplifier and transformer Carefully remove the amplifier and place it on a workbench or table where you can install the power transformer 4 2 Installing the Power Transformer It is recommended that the power transformer be installed when the amp is at or near the place it is to be used The chassis of the 8410 is designed for the mechanical loads it experiences when the amplifier is on a flat surface with the tilt bail up or down If the amplifier is ti
21. ier transmits but red GRID LED illuminates often 1 Amplifier overdriven or under loaded Reduce transceiver output and or increase amplifier loading 2 Load VSWR reflected power exceeds f Check output cabling and antenna Correct 200 W impedance mismatches 3 Exciter output poorly controlled Consult exciter s User s Manual for assistance on controlling output Receive signals disappear or are severely attenuated when switching from 40 STBY to OPR 1 RELAY T R control cable from Check T R control cable to make sure it is transceiver is shorted switching properly Replace if needed 2 Transceiver locked in transmit Make sure transceiver is properly switching between transmit and receive See transceiver s User s Manual for assistance Plate current indicated when amplifier is in STBY or receive 1 VTX X118 tube heater to cathode Contact Alpha Customer Support leakage or short n EN Contact Alpha Customer Support Distorted SSB signal Grid bias is unexpectedly decreasing 1 Excessive RF drive from transceiver Decrease drive from transceiver Re check and or insufficient amplifier loading amplifier tuning 2 Coaxial connector coax feed line antenna feed point balun tuner or antenna trap arcing on voice peaks 3 RF feedback from antenna into Make sure all power cords microphone and transceiver via the transceiver power cord key cables or other cables are properly microphone or key
22. ings If an antenna has been deployed for a long period of time it may be worth taking it down for inspection prior to full power operation If any insulators are cracked or show signs of tracking in this part of the band 3 5 Coax and Connectors The importance of a well constructed feed line system cannot be overstated After all the purpose of the amplifier is to provide approximately 2 S units 12 dB of improvement in your radiated signal All too often installation problems are encountered where cheap poor or under rated coax and connectors are used These often are responsible for at least one S unit of degradation This means you could have bought a 375 W amplifier and achieved the same radiated signal by buying good quality feed line components Use the lowest loss 50 ohm coaxial cable you can obtain Use new clean connectors installed according to the manufacturer s recommendation Clean the connectors after soldering them and before mating them with the amplifier Make sure any excess solder is removed from the connector likewise remove any fragments of braid etc Never use old coax which may have had moisture penetrate under the jacket Support the coax frequently using non compressive clips so that it does not hang or stretch under its own weight Avoid sharp or kinked bends most manufacturers will specify a minimum bend radius for their product Make sure the connection from feed line to antenna is waterproof Provide
23. ithin a few milliseconds This system has virtually eliminated RF arc damage in current ALPHA amplifiers The system similarly detects severe miss tuning of the 8410 and if 36 drive exceeds about 25 W switches the amplifier to standby The 25 watt input trip threshold permits safe tune up at low power levels without aggravating and unnecessary trip outs 6 5 Standard Maintenance Tasks The amplifier interior particularly high voltage areas should be cleaned with a vacuum cleaner and a soft bristle brush frequently enough to prevent visible accumulation of dust In extremely dusty conditions it may be advisable to secure a thin air filter of the type used for window air conditioners across the air intake on the rear panel There are no user accessible lubrication points in the amplifier Do not apply oil or grease to any of the components The exterior of the ALPHA 8410 may be cleaned with a mild household liquid detergent Do not use chemical solvents as these may severely damage the front panel or cabinet finish Never use an abrasive cleaner The amplifier should be cleaned at least once a year and all dust should be removed This include blowing out the cooling fins in the VTH H118 Tetrodes 37 Blank Page 38 Troubleshooting Hints 7 1 Normal Troubleshooting 8410 will not turn on nothing happens when ON switch is pushed Problem Correction 000000 1 External AC wiring fuse or circuit Check amp correct wiring replac
24. lifier in its operating position The amplifier with the transformer installed is heavy so you may need assistance to safely move it Make sure it is placed on a stable surface and that there is sufficient space to the rear sides and top to allow good air flow and safe placement of cables 4 5 1 GoaHial Cable Types amp Connectors Connect the transceiver RF output to the ALPHA 8410 RF INPUT connector with 50 ohm coaxial cable RG 58C U or equivalent Coaxial cable from the 8410 RF OUTPUT connector to the antenna should be RG 8A U RG 213 U or RG8X cable is not interconnection when used with a modern QSK transceiver 4 5 2 T R Control Cable The Alpha 8410 has a full break in vacuum relay QSK system requiring only the normal interconnection when used with a modern QSK transceiver The Alpha 8410 requires a contact closure short circuit on transmit from its RELAY jack center pin to chassis This function is supplied by the transceiver usually from a dedicated relay that is normally open in receive and closed in transmit Shielded wire should be used for the T R control cable The Alpha 8410 end must be fitted with a common phono RCA type plug and the other end with a connector suitable for the transceiver The T R relay contact must close before application of RF drive The Alpha 8410 protection circuitry prevents hot switching with RF drive applied Modern transceivers have the proper time delay between key up and the start of the tran
25. line They hold via contacts on the trip relay on the HV board The regulated minus 12 volt and minus 124 volt supplies are also located on this board Many of the important voltages for the amplifier are brought to test points on this board 24 5 5 High Voltage Board The main high voltage for the amplifier is created on this board using a full wave bridge rectifier and a bank of capacitors This power supply has two 10 ohm resistors one in the positive B lead and the other in the negative return which goes to ground The combination of these two resistors limits the surge current in the case of a B arc The voltage across the resistor in the negative return is used to monitor tube plate current in the control board This voltage is also used to generate the hard fault condition When the power supply current exceeds about 2 to 2 5 Amps a relay operates to open the coil circuit of the mains tap relays on the mains board When these relays release the amplifier goes to the power off state This hard fault circuit operates independently of microprocessor control The regulated screen supply is also located on this board All power supply filter capacitors on this board have bleeder resistors which will discharge the capacitors in less than 60 seconds If it is necessary to work on this board it is nevertheless recommended that the discharged condition be confirmed with a voltmeter due to the remote possibility of bleeder resistor failur
26. lted too far such that the transformer is cantilevered or hanging out to any degree the chassis of the amplifier can distort This may affect a number of things from the alignment of screw holes on the top cover to the band switch alignment and tension If the amplifier is moved even if only from one site to another locally remove the transformer to avoid the possibility of damage CAUTION Do not operate amplifier without the cover in place and all cover screws installed Do not operate the amplifier without a good ground connection on the rear panel ground terminal Make sure all RF cables have a solid ground shield in place WARNING The transformer is very heavy and must be moved with due caution using only the lifting handle CAUTION PROCEED SLOWLY to avoid bumping and damaging adjacent wires connectors or components 15 While the top cover is removed make sure each tube is firmly seated in its socket rubber exhaust chimneys are fully and correctly installed and anode connectors are tightly clamped to each tube The silicone rubber chimneys installed on the VTX X118 tubes are a critical part of the cooling system Make sure the chimneys are straight and fully installed so the bottom of the chimney is firmly against the tube deck and completely covers the airflow openings in the deck Make sure that the silicone rubber chimneys are flush with the top cover when it is placed back on the amplifier Tube cooling exhaust
27. nes the power level at which best efficiency and linearity are achieved In general loading is heavier at greater scale settings Higher frequencies tend to load more toward the 100 end of the dial scale and lower frequencies toward the 0 end 6 3 2 Tune Up The objective of tune up is to adjust the amplifier and the drive applied to it to obtain optimum efficiency and linearity at the desired output power Any linear amplifier must be adjusted for optimum efficiency and linearity at each specific power level If operation at higher power is then attempted without appropriate readjustment the result will be flat topping also known as splatter and usually excessive amplifier grid current If operated at a much lower power level than it has been adjusted for the amplifier s efficiency decreases considerably Recommended practice is to tune first into a dummy load or artificial antenna then connect the antenna and make any slight final adjustments that may be needed Alpha Radio Products makes the ALPHA 2100 in line dummy load which simplifies this process Using the AP 2100 the operator can switch between the dummy load and the antenna at the flip of a switch 6 3 3 Grid Current Information The ALPHA 8410 operates in Class AB1 when delivering maximum output power consistent with excellent linearity A small amount of grid current flows and the green GRID MIN LED illuminates as drive approaches the optimum level The gre
28. nly on for the duration of each dot or dash and switches to receive between each RCA Radio Corporation of America Also a type of interconnecting plug RTTY Radio teletype SSB single side band SSTV Slow scan television STBY Standby SWR Standing Wave Ratio A measure of antenna and feed line efficiency T R Transmit Receive UHF Ultra High Frequency 300 3 000 Mhz 43 US United States VAC Volts of alternating current VDC Volts of direct current VSWR Voltage Standing Wave Ratio Manual written by Mike Higgins AGAER End 44 Blank Page
29. ny time the amplifier is plugged into the mains power this 5 V supply is active and there is power to the micro controller on the main control board This feature allows the amplifier to be turned on or off remotely as well as remote monitoring and debugging though a USB cable connected to a computer 5 2 Tubes The amplifier is designed to use two VTX X118 tetrode tubes The amplifier design uses these tubes well within their ratings The two tubes are operated in parallel and the Alpha 8410 is designed with the expectation that a matched pair of tubes will be used in the amplifier Alpha matches tubes received from the supplier to within 10 for power output and gain when operated in a standardized test fixture Note that power output efficiency tube life and amplifier reliability may be compromised if tubes are used that do not meet Alpha s matching criteria Any damage sustained as a result of using unmatched tubes may not be covered under warranty The tubes are operated in Class ABI with a plate voltage of 2 800V nominal full output key down a grid 1 voltage of 50 60 volts and a grid 2 voltage of 200 volts The tubes have an inductance resistor in series with their cathodes This resistor stabilizes the tube bias and provides negative feedback which improves linearity and hence IMD performance Electronic bias switching EBS increases the negative grid 1 voltage in pauses in speech or between Morse code elements This reduces the st
30. other it switches the input RF to the tube matching circuit The tubes are operated as a swamped grid tetrode design The tube grids are tied at RF to a 50 ohm swamping resistor which absorbs most of the input drive power The RF voltage across this resistor is added to the grid 1 DC bias to provide the net low impedance tube grid 1 bias The RF impedance represented by grid and its capacitance is compensated for by a series inductance to provide less than 2 1 SWR on each band at the amplifier s input At higher frequencies a relay switches in a separate matching network This relay is under microprocessor control and is actuated according to the band switch setting 5 5 Mains Board The power supply functions are split between the mains board and the high voltage HV board The mains board mostly deals with the primary side of the transformer The various taps for the transformer primary are routed through this board and so is the AC line input Relays on the mains board connect the AC line to the appropriate taps on the primary One of 5 tap options is selected by using a 5 way jumper field See section 4 3 for more details on how to set the jumper Also on the mains board is a step start circuit This circuit consists of a relay and a resistor which are time sequenced to limit the inrush current into the amplifier when it is first turned on When initially turned on the tap relays operate from a voltage derived from resistors from the AC
31. r choice for voltage control a ferro resonant voltage regulator is an expensive solution but is a good way to stabilize primary voltage Note If you intend to operate the amplifier on any of the 90 130V settings the lower 2 amp fuse on the rear panel will have to be changed to 5 amp to allow for the increased in rush current FIGURE 4 2 1 Amplifier Interior Output Tank Circuit TH H118 Tubes en c Tube Parasitic Choke i s attachment point Pi RF Connector Cooling Fan 3 put RF Connector V Safety Switch AC Transformer Molex Input AC safety Switch Transformer Relay and HU AC Transformer AC tap PCB 18 FIGURE 4 2 2 Amplifier Rear Air Inlet Key line Input Output AF Input RF Output va3 1913701 omPALL BEARINGS TAL MOTOR CO LTD MADE IN JAPAN S Chassis AC Fuses AC Cord NSB Input Ground 19 Input AC tap settings can be made by moving the flying lead to the _ a marked AC spade posts ee marked in the appropriate voltages The proper taps must be N u made before the ac ai J power is applied When o a A making changes make 20 J21 J22 J23 sure the amplifier is i ek unplugged se aw A Never use a tap other than the proper voltage or damage to the tubes and amplifier will result lying lead attachment points Figure 4 3 AC Power Setting With the top cover removed the primary voltage taps are located on the top of the Mains Board which is between th
32. rgy from nearby electrical storms or other power transients may damage components in the amplifier Such damage is not covered under warranty It is important to use a good lightning arrestor however the only lightning proof solution available is to disconnect antenna feed lines and AC power when the equipment is not in use 6 1 6 Operating in Bypass Mode Whenever the 8410 is in line either off in standby STBY or in warm up with the WAIT LED lighted the amplifier is bypassed and the exciter is connected directly to the antenna The throughput limit in all cases is 500 watts when operating into a 1 1 SWR This power level should be reduced accordingly for a higher SWR Any power level more than this may damage the RF switching relays in the 8410 eg 6 2 Transceiver Connections The Alpha 8410 relay jack has approximately 12 V on it When pulled all the way to ground a current of 10 mA flows Consult your transceiver manual for additional information on how to connect to an external amplifier 6 3 Initial Setup and Tuning 6 3 1 Control Functions The following chart shows the controls that allow you to adjust and monitor the amplifier BAND Used to select amateur band desired in MHz Sets output tank circuit to resonance within each band Higher frequencies tend to tune toward the 0 end of the dial scale while lower frequencies tend to tune further toward the 100 end Sets amplifier plate loading and determi
33. smitted signal to allow the Alpha 8410 to follow the CW keying Ifa T R timing problem is suspected connect the CW keyer to the RELAY jack on the Alpha 8410 and connect a cable from KEY OUT on the amplifier to the keying input of the transmitter el 4 5 3 ALC The Alpha 8410 does not generate or use ALC voltages to control an exciter For proper operation the exciter transceiver should have its power output set so as not to over drive the amplifier input Today s modern transceivers have very good power output limiting As a rule ALC is not needed if the transceiver is less than 15 years old Should your transceiver be older then the power output should be reduced so voice peaks will not overdrive the transmitter under any modulation condition ec 5 Theory of Operation 5 1 Theory of Operation Overview The Alpha 8410 uses tetrode vacuum power grid tubes as the amplifying devices The main power supply is an unregulated transformer rectifier capacitor power supply for the high voltage HV and heater circuits All other power supplies are regulated The control circuit uses a microprocessor in the loop to monitor and control amplifier operation There are 7 circuit cards in the amplifier In addition to these the tubes tank circuit assembly and transformer complete the main sections of the amplifier These major blocks are described below The 8410 amplifier includes a 5 V power supply that is mounted behind the front panel A
34. t as close as possible to where you expect to operate the 8410 If you are not sure or contemplate moving the amplifier you may choose to get a second outlet installed at the same time Ask your contractor for two or three matching plugs during installation as there are several styles of connector available Ask the contractor to measure the voltage and record it so you can set the line voltage tap on the 8410 appropriately If possible have the contractor measure the line voltage with a 10 amp current draw and use this value for setting the transformer tap The Alpha 8410 can run when connected to an 120V AC outlet However you WILL NOT achieve full legal limit output in this case If the amplifier is connected to an 120V AC outlet you should not expect more than 1000 W output 3 3 Air Flaw It is critical that airflow around the Alpha 8410 remain unimpeded at all times Keep the top of the amplifier clear of any restrictions If you are mounting the amplifier in a console make sure that the exhaust air is properly and fully removed from the console 11 Figure 3 3 Minimum clearance for proper airflow Keep top tube exhaust clear Keep rear intake clear Make sure the exhausted air cannot be recirculated back into the amplifier air intake Too ensure adequate cooling ALPHA na ae ae RE make sure the top and rear of urn gt Te your amplifier have at least 3 wam l of clearance to allow BOAT yy unobstructed airflow
35. t to the two hot wires of the AC source either wire may be connected to either side of the line For best results use a dedicated 200 240 V branch circuit of 10 AWG copper wire or equivalent rated at 20 A to feed the amplifier 16 4 2 4 Important Information about Operation from 90 130V AC Electrical power equipment will draw twice as much primary current from 120 V mains as from 240 V mains Therefore operating the ALPHA 8410 on a typical 120 V 20 Amp household circuit without exceeding the 20 A circuit rating will limit maximum peak power output to about 6001000 W Maximum possible RF output power for any particular primary AC voltage and current capacity may be estimated as P max V xI 2 3 For example if the Alpha 8410 operates from a circuit that is capable of delivering 120 V AC at a maximum current of 20A with no other loads connected to the circuit maximum peak RF output possible without tripping the 20A breaker or fuse is approximately Py max 120V x 20A 2 3 2400 2 3 1043 W If the same circuit also supplies a transceiver drawing peak line current of 5A and a lamp drawing 1A only 20 5 1 14A is available for the amplifier and maximum possible output is about Po max 120V x 14A 2 3 1680 2 3 730W Below are some considerations at the high end and the low end of this voltage range that are rarely encountered Low Voltage vs Power Output At the low end of the voltage range do not expect to
36. t type 3 Both Ip and HV LED s are blinking This indicates that the gain of the amplifier has fallen below 10 dB This is an important safety feature of the amplifier as many different problems in the amplifier or with its operation can be detected as a drop in gain To avoid this fault occurring while the amplifier is being tuned up the gain fault detection is disabled when drive power to the amplifier is below approximately 20 watts This allows correct initial amplifier tuning to be achieved before going to full power Fault type 4 HV LED is blinking This indicates a reflected power fault The 8410 is set up to trip when the reflected power exceeds approximately 300 watts At 1 500 watts output this would represent an The fault type codes above are also reported in the amplifier telemetry data via the serial or USB ports on the rear of the amplifier If the tube current exceeds about 2 5 amps the amplifier is shut off completely that is the AC is shut off The ON OFF switch will need to be used to put the amplifier back on line To avoid problems wait at least 20 seconds after this occurs before attempting to put the amplifier back on line If the amplifier trips again immediately investigate and cure the problem before attempting to turn the amplifier on again Repeatedly hitting the ON switch when the amplifier trips out is likely to result in severe damage to components in the amplifier If a hard fault trips the amplifier all the
37. tput e Capable of full CW break in QSK and all digital modes when used with any appropriate transceiver e Protective functions are built in The control system incorporates protective functions that minimize the probability of accidental damage to the amplifier or its power tubes In most cases when one of the protective functions is tripped the amplifier will go to Standby 1 3 Shipping Information The Alpha 8410 amplifier ships in two heavy duty cardboard cartons One carton holds the power transformer and weighs 43 Ib 20 kg and the second carton contains the amplifier and weighs 38 Ib 17 kg Both of these cartons are mounted on a wooden pallet and strapped down for a total weight of 98 1b 45 kg Alpha recommends that you retain the pallet and the cartons after installation in the unlikely situation that you need to ship the unit later Contact Alpha at 303 473 9232 for shipping advice and assistance 1 4 Safety Information Installation and Operation e Make sure the Alpha 8410 is located where there is good air circulation all around and on top of the cabinet The unit may become hot during operation e The Alpha 8410 weighs approximately 70 pounds when the transformer is installed Use proper lifting techniques and two people when moving the amplifier Note that amplifier should NEVER be transported with the transformer in place e The Alpha 8410 is designed to meet international safety standards and FCC regulations Ho
38. ut is desired increase drive from radio slightly increase LOAD for a peak in RF out then peak RF out with TUNE control When the amplifier is tuned correctly on 160m thru 40m the Ip should range between 0 9A and 1 1 A read on the 0 to 1 5A scale for 1500W output and input drive should not need to be more than about 60W On 20m the Ip will usually be about 1 0A for 1500W output Plate current Ip is the most useful parameter to monitor on the multimeter bargraph during normal operation of the amplifier 33 Alpha Radio Products alternate tune up procedure Nominal Gain Method Tuning up for Operation at 1 500 W RF Output Preset BAND TUNE and LOAF controls to the nominal positions given in your amp s specific tune up table or Table 6 3 Note Final TUNE and LOAD settings will vary with the operating frequency antenna characteristics and power level l 2 10 1 l Reduce transceiver carrier output control to ZERO Press OPR operate on OPR STBY switch OPR LED should illuminate Select the TUNE function of the multimeter bargraph Switch transceiver to CW and increase its carrier output to approximately 15 W 8410 output will be approximately 300 500 W Adjust the TUNE control to deflect the TUNE LED maximum rightward Adjust the LOAD control to place the illuminated TUNE LED in between the white lines above and below the LED bargraph Repeat steps 5 and 6 at least twice Increase the ex
39. wer should immediately begin to operate If there is no air flow from the amplifier and no sound of blower operation immediately turn the amplifier off and investigate 4 Within two seconds the HV display should be all the way to the right certainly above 2 500 Volts If it is lower than this investigate further perhaps the primary taps are not correctly set o At this time the red LED representing 1800 W output power is illuminated indicating 180 seconds countdown remaining 1800 10 180 seconds As the timer counts down the remaining time will be indicated by the currently illuminated LED on the power output bar graph moving to the left 6 Move the multimeter switch to the Ip position There should be no current indicated and this should be true during the entire period the amplifier is warming up Leave the switch in the Ip position during amplifier warm up The Wait LED will be blinking about twice per second indicating that warm up is still in progress The FAULT OPER and STBY LED s should not be 31 illuminated CAUTION EHHAUST AIR MUST BE DETECTABLE FROM BOTH TOP VENTS If exhaust air is not coming from the top vents TURN OFF the amplifier immediately and verify that the exhaust chimneys are properly positioned over the tubes When the warm up delay is complete the WAIT LED will extinguish and the OPR or STBY lights will stop blinking Put the OPR STBY switch to OPR and the Alpha 8410 is now ready 10
40. wever one should always remember that the equipment works with high voltages that can be LETHAL This operating manual holds information cautions and warnings that must be followed to ensure safe installation and operation Read Chapter 1 before attempting to unpack or operate the Alpha 8410 amplifier Warnings What Not to Do e Never open the amplifier case without unplugging the unit from the wall outlet e Always resist the temptation to immediately hit the ON button after the amplifier faults to power off e Never touch an antenna during transmission e Never attempt to turn on the amplifier without the cover securely in place all attachment screws reinserted e Never turn the amplifier back on after a hard fault without waiting at least 20 seconds e Never allow liquids to enter the amplifier through the cover holes e Never stick objects into holes in the case Warnings posted in this manual should be read and thoroughly understood by users Failure to perform procedures properly may result in amplifier damage fire hazard or electric shock 1 5 Owner Assistance Technical Assistance from Alpha Radio Products is available from several sources e The Alpha Radio Products web site is www alpharadioproducts com Click on Support and follow the instructions Many typical problems and their solutions are listed on this site On this site you can get the following assistance Technical Support Repair Information Software Do
41. wnloads Manuals Tech Tips Legacy Equipment Information FAQ s Alpha Forum You can email us for customer support at service alpharadioproducts com OF you can send your request by fax to 303 473 9660 or call us at 303 473 9232 Blank Page 2 Quick Start Information 2 1 Overview This section explains in brief the items you need to consider when setting up your Alpha 8410 amplifier If you already have a well designed shack and have used an amplifier before please review the items below to make sure you have considered all the critical items for proper installation and operation If you are using an amplifier for the first time please skip this section and go to sections 3 4 and 5 for a more detailed explanation of how to set up your shack for maximum safety and operating enjoyment If you have installation questions do not hesitate to contact Customer Support We much prefer to address questions prior to power up 2 2 Station Engineering Considerations Checklist Make sure you have properly addressed the following concerns Section 2 3 below before installation of your Alpha 8410 amplifier If you are unsure of any of these items please read the noted sections carefully 2 3 Preparation ___240V AC Power in shack Section 3 2 __ Amplifier placed with proper airflow Section 3 3 __ Antenna ready for 1 500W Section 3 4 __ Adequate RF cabling Section 3 5 2 4 Unpacking Unit Checked for Damage _
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