EFRATOM LPRO 101 Repair Guide
Contents
1. E 3G2 28 _ 22 AMISTWASHL lt fi 96 _ IEJ 4 T 4 SAV 027 EB L Q0 1017 I bcd vL 3 J4 BE 4549 gt Am 89 Vv 2333 iul m 079 gt oza EB 9 qv 28 HMM gt 06 BL ccs 39anns 7 Gh it BEA 3 16 Fig 13 Lamp heater diagram sub 2 LPRO repair reference guide SMD diode reference CR101 CH106 or F101 CR102 SMBYWO2 100 BYWO2 SMBYWO2 100 SMD CODE ER10 SMD diode reference by SMD code oD MMBD914 1N914 SMD transistor reference by SMD code 1 P1F 1JA SMD IC reference U101 U102 U103 U201 U202 U203 U204 U301 U302 U401 U402 U403 U501 U701 U702 VR101 VR103 VR701 MMBT2222 A PZI2222 A MMBT2369 A LMC7101 AIM5X LMC6482 IM TLC272 LMC6482 IM TLC272 LMC6484 IM TLC274 LMC6484 IM TLC274 MC14053 B LMC6484 IM LMC6484 IM LM615 IM 74 08 74 74 LMC7101 AIM5X 709 TLC2272 TLC2272 LP2951 CM 2 LM285 TLC274 TLC274 LPRO repair reference guide 17 Tuning the unit Once you have a locked unit you can tune the SRD bias and the 6 8 GHz cavity Allow the unit to warm up for 10 minutes You can only do this after a lock has been established If you don t have a lock you probably make things worse by adjusting2. S c SO 50 Wor 22 gt zx i o9 Cro LL gt cQ Revision 2 August 2008 PE1FBO LPRO repair reference guide Contents Brel SDGGS 4 mid looo 4 Temperature controlled 5 14 VOUS SCCUON n E HAE ICE CU P PU e 6 S VORS MENNO 7 VCO and input protection 8 VCO Section Z0MFIZ ar A t D Facts Dd Rack Rav ad a 8 9 Hb cell connections SRD and 10 SRD Bias Step Recovery 10 Rb cell connections Thermistor and Photocell 11 sede te tested 12 POSSIDISTAULS OD TAG Ulo oor 13 Note on replacement of the Rb cell heater transistors 14 Tanam c mE 14 LOCALON OL R S I E 14 Lamp heater alagratri SUD 122i nisin asa 15 Lamp heater dradrammi SUD 2 otis dad 16 SMD diode nennen nennen nnn 17 SMD diode reference by 17 SMD transistor reference by SMD
3. range is rather big 150 Hz for the 10Mhz output 9 999 850 10 000 180 Hz Total time for a complete scan takes about 105 seconds 60s ramp up 45s ramp down The internal VCO works on 20MHz The 20 MHz crystal is housed in the round package with heat sink on it LPRO repair reference guide 8 Lamp exciter diagram TR UL PAE S080 95 Se eee ee 7 ip 00015 Sogo 8 PUE q96 WIT OG 009 wed D wa TS o joa disi zx Det eat ee yee ee he he 4 97 n l ps 07 2 5 102 cogo OdN IU Se P T 0 3615 9021 9021 48 10 ai 9299 T 9 06 y 4 E D ini SS d ub EP a 1 By 190001 xy 19 ip cab Ao a CRIT ORR REN J 7 6 i 2044 9 MI 3001 CYA Fig 7 Diagram of Rb lamp exciter LPRO repair reference guide Rb cell connections SRD and C field gt Ei 4 S76iASSY MN a 1 102580 dim PE C21 oe fos v lon f 7 In e J9 c C field coil connection HF to cavity SRD bias pot Fig 8 Rb cell connections SRD Bias Step Recovery Diode The SRD bias potentiometer is typical set between 1 5 and 4 kOhms If you
4. the lamp heater you could check if the voltage over the 2 Ohms resistor backside is about 0 4 Volts this corresponds to 200mA LPRO repair reference guide 13 Note on replacement of the Rb cell heater transistors Efratom has used a fusing kind of isolation pad to mount both heater transistors This results in a very low thermal resistance from transistor case to the aluminium base If you replace the transistors it is important to restore the original low thermal resistance With an increased thermal resistance the lock time increases as well and the of the unit is also negatively affected since the junction temperature of both heater transistors will be higher Tantalum caps On an old unit the tantalum caps have possibly a high ESR or are completely open would replace them with new ones since the units run at high temperatures and this has an accelerated aging effect on the tantalum caps Location of R705 and R731 Fig 11 Location of R705 R731 LPRO repair reference guide 14 Lamp heater diagram sub 1 1115817 NUILVIIJX3 A TAWASSY Q 5 poe ANY Sav 2 21 ge E Oe 91 5 amp Q Qe BEN lS el V3H Ave 81 15 LPRO repair reference guide Lamp heater diagram sub 2 p 38 ams ZEN vola 30 0 SC g la ac Z SNISTIDH T
5. the settings on the unit CUBEHHEAT BEL vide E NE 4 904 E1 Ec HN CE E i 215 TUS 102580 Bate Fig 14 Test point J5 corner pin LPRO repair reference guide 18 280mv 8 08 V 6 52115 4 12m5 Ch1 4 64 V SM 500 zooms A Chi fF 9357 13 Jul 2008 0 00000 s 14 15 28 Fig 16 Wave form 45 Tune both adjustments for maximum Vpp LPRO repair reference guide 19 Efratom Rubidium synthesizer schema A part 10 MHz 6 60 MHz 114 60 MHz 6 840 GHz B part 10 MHz 2 5 MHz 5 MHz 16 0 3125 MHz 5 MHz XOR 0 3125 MHz 5 3125 MHz A and B are mixed one of the components is 6 840 0 0053125 6 834 687 500 GHz Hyperfine resonance frequencies according to NIST Rubidium 6 834 682 608 GHz Hydrogen 1 420 405 752 GHz Caesium 9 192 631 770 GHz Difference of frequency NIST measure and Efratom synth is due to buffer gas in the Rb cell that has a positive offset on the resonance frequency LPRO repair reference guide 20
6. RFU220 802 IRFU220 Fig 3 Temperature controlled assembly The Rubidium lamp housing is about 101 Celcius The Rubidium cell is about 71 Celcius The official temperatures according to the manual are 110 C for the lamp and 79 C for the Rb cell The housing of the heated assemblies measures lower Both samples had this It is also depending where you measure the temperature The base plate needs to be mounted on a heat sink to prevent loss of lock and thermal runaway of the internal electronics As a test you can operate the unit without heat sink for about half an hour to check if the electronics work reliable at higher ambient temperatures The TO202 heater transistor is a MJE802 NPN darlington 4A 40Wait this can be replaced with an BD679 or BD681 The TO251 transistors on the lamp and Rb cell are IRFU220 MOSFETS 4 6A 200V 40 Watt They can be replaced with an IRFU420 or STD3NB30 The Rb lamp exciter transistor is an MRF160 its a MOSFET from Motorola Ft 500 Mhz 4W 28 volts A possible substitute could be the PD57006 from ST LPRO repair reference guide 5 r Murus 17 14 Volts section ui ne D e EE Be COS ict fc m D sef Zr CeramicC 2N6490 4u7 35V 7805 Fig 4 17 Volts section and 14 Volts section Power transistor Q106 is originally a 2N6490 it is a 15Amp PNP low hfe type It can be replaced by an MJE2955T or BD912 if faulty The collect
7. case l ve found it shorted If the transistor seems OK check resistors in the vicinity even on the upper side of the board In one case I ve found R705 bottom 100K interrupted It should read onboard about 82K If the lamp assembly doesn t heat check H731 bottom of PCB In one case had a faulty lamp It can be inspected quite easily Unlock the hexagonal nut and unscrew the lamp taking note of how much it protruded from the assembly Don t touch the lamp with fingers A good lamp has a delicately brownish glass a lamp which leaked has transparent glass with some small white pigments It you tried turning the lamp assembly trimmer in order to increase lamp volt you could have forced it causing the rotation of its hot not ground lead and possible short on the coil inside the lamp assembly would say all 100k resistors of this size on the board are suspect They are of the 0603 SMD size and marked with 104 The smallest parts on the board If there is a problem with the heating of the Rb cell check if the emitter of the MJE802 is at 12 volts This is about half the supply voltage and follows the input voltage The voltage over the current sense resistors backside is about 300mV This is when the Rb cell is cold There are 1 2Ohm resistors in parallel Current is 850 mA Voltage on the gate of the IRFU220 when stabilised is about 4 4 volts on the source it is 70 mV Drain voltage is 12 Volts If there is a problem with
8. code 17 wi BE el TEM 17 TURING the BE edet etate etre ves d eva led ted bird 18 Efratom Rubidium synthesizer schema 20 Hyperfine resonance frequencies according to 20 LPRO repair reference guide 2 _ _ TIME amp FREQUENCY PRODUCTS INC Covered by one or more of the U S Patent Mos 4 661 782 5 457 430 5 489 821 and patents pending 14 CAGE CODE 55761 RUBIDIUM FREQUENCY STANDARD MODEL LPRO 101 102500 001 Fig 1 Connections LPRO repair reference guide Brief specs Input voltage 24 V DC 19 32V Input current when cold is about 1 25 Amp when the lamp ignites it becomes 1 19 Amps Input current when warm is 0 35 0 45 Amp Time to lock when cold is 3 to 5 minutes Rubidium lamp Fig 2 Rubidium lamp When the rubidium lamp section reaches 40 to 60 Celcius it ignites you will see the purple light coming from the back of the lamp Mind you that when stray light 50Hz or 60Hz enters the rubidium cell the whole unit starts to behave very strange so be aware of this Lamp voltage pin 5 can be as low as 3 Volts below 3 volts an atomic lock becomes difficult Healthy units are ranging from 6 to 9 Volts LPRO repair reference guide 4 Temperature controlled assemblies EC d 2 Hi 4 xy gt af m 1 1 lic I
9. disconnect the yellow coax cable you can measure the SRD forward voltage drop of 0 7 Volts center to shield LPRO repair reference guide 10 Rb cell connections Thermistor and Photocell Thermistor connection Photocell connection Fig 9 Rb cell connections LPRO repair reference guide 11 C field adjustments 6 x 020 12 8 11 D T Q10 PZT2222 H126 R116 Fig 10 C field resistor 10 000 000 002 10 000 000 050 10 000 000 165 With increasing current trough the C field coil the frequency increases By adapting R126 you can tune the unit with potmeter R116 to exactly 10 MHz The C field coil is approx 18 Ohms Q10 is a PZT2222A P1F marking This is 2N2222 in SOT223 SMD package LPRO repair reference guide 12 Possible faults on the unit Quote from Antonio 8 Before inspecting the lamp suggest the following checks Check that the lamp housing gets VERY hot in about 1 minute 100 Check that the physics unit on the other side of the foam gets hot too 70 Check the presence of the HF field You could use a counter Using a link of one turn of wire check if you can read a frequency of about 70 or 140 second harmonic MHz approaching the link to the MHRF160 power mosfet if you read 60 MHz you are picking up the field of the physics unit not the field for lamp then orient better the link If you don t see the signal check the transistor on board In one
10. or mounting tab of Q106 should be at 17 0 Volts to GND Q106 is isolated from the chassis The additional black capacitor is 1uF 50Volts ceramic had to remove the one on the back side which was suspected to be short at higher temps There is not enough clearance on the back side of the PCB to have it fitted there The capacitor C116 is a tantalum one 4 7uF 35V The positive terminal of this capacitor is about 14 4 Volts to GND The voltage regulator VR102 is 7805 it s output is at 5 Volts to GND LPRO repair reference guide 6 volts filterin L E 5 11 1 Vu Ed Xy E v y m DEUS a 9 3 Css e 0 368 Im 195085 28 Fig 5 5 Volts filtering The two SMD tantalum capacitors can be replaced by SMD tantalum ones of a different value The original ones where 68 uF 16Volts The new ones used are 33uF 16 Volts The positive terminal of C419 is about 4 6 Volts the other cap s voltage is about 4 4 Volts to GND Both are used to filter the 5 Volts supply LPRO repair reference guide VCO and protection diodes Fig 6 input protection diodes and VCO Both diodes CR101 and CH 106 F101 are SMBYWO diodes with a forward voltage drop of 650 mV Both anodes are connected to the input of 24 Volts the cathode is 23 35 Volts VCO section 20MHz Oscillator
Download Pdf Manuals
Related Search