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Service Group TR7 Alignment Procedures
Procedure that the Drake service group used to check out the TR-7 at the end of every repair operation.
Repair reported problems. Perform the following checks, some may have been covered in repair.
GENERAL CHECKS
1) Check for 470 or 500 microfarad capacitor (3180260) on chassis under power supply board, on
+10 V line from pin 3 (gnd) to pin 10 (+) (count pins from parent board). This is necessary +10 V
filtering.
2) Check for surge arrestor (342-3000) from EXT ANT Jack to ground at KEY jack (parallel with 3 PI
choke) at back chassis. This prevents diode and double balanced mixer damage from lightning
and other surges.
3) Clean Jones connectors as necessary. Check proper value 5 amp fuse.
4) Turn unit on. Check +10 VDC line. Check +10 R (slightly less than 10 volt line in receive, no
higher than 0.2 V transmit). Check +10 T (slightly less than 10 volt line in transmit, no higher than
0.2 V receive). Check +5 VDC line. All these on parent board.
5) Check on the chassis plug in unit for power supply board, 2nd pin from parent board +24 VDC
line (23.25 to 24.00), and Ist pin from parent board -5 VDC line (-2.5 to -3.5).
6) Check UM9401 pin diodes on the high pass filter assembly, rear.
ANODE CR1501
JUNCTION CR1502, CR1503
7) Check bias an PA transistors, base lead. On drivers, be careful not to short B to C, this will
destroy the transistor.
DRIVERS
FINALS
8) Check band switches, front panel switches, rear panel switch, front panel controls, and plug in
boards for any intermittent operation.
9) Check MPN3404/1S2186/1SS135 CR1401, CR1402 calibrator diodes on the high pass filter
assembly front. Checks can be done with an ohm meter or by signal check. To do signal check,
inject a 0.5 micro volt signal on 7309 KHz and tune in signal noting dB level on an AC voltmeter
connected across speaker. Turn on calibrator, AC level should drop 2 to 3 dB.
10) Minor check of all oscillators, 40 MHz, 53.695 MHz, 5.645 MHz.
RECEIVE
TRANSMIT
MAX 0.9 V
11V TYP
11 V TYP
MAX 0.9 V
RECEIVE
TRANSMIT
0 V
0.70 V TYP
O V
0.65 V TYP
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Table of Contents
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Summary of Contents for DRAKE TR7
- Page 1 Service Group TR7 Alignment Procedures Procedure that the Drake service group used to check out the TR-7 at the end of every repair operation. Repair reported problems. Perform the following checks, some may have been covered in repair. GENERAL CHECKS 1) Check for 470 or 500 microfarad capacitor (3180260) on chassis under power supply board, on +10 V line from pin 3 (gnd) to pin 10 (+) (count pins from parent board).
- Page 2 TRANSMITTER ALIGNMENT 11) Predriver pot should be set full counter clockwise on version 2 board, about 12 o'clock on version 1 board. But it is best NOT to re-adjust this pot on version 1 of this board (the one with two SRF2281s) unless necessary.
- Page 3 FINAL RECEIVER ALIGNMENT (Back cover shield (or test shield) installed, check and align steps 26 through 29 only as necessary). 26) Tune radio to a non-calibrator frequency, like 7.309 MHz, on fast AGC, calibrator and PBT off. 27) Set generator to the same frequency, output for about S5 to S7 on the meter. On the 2nd IF/Audio board, peak L1101, L1102, T1102.
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