RA6790/GM

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Technical Details

RA6790GM CONFIGURATIONS

ASSY RA6790/GM AD6 GM20-AD11 AD12 GM-13 GM3/GM-13 AD-16 GM-19 AD-19
A0 N/A N/A N/A N/A N/A N/A 9621 N/A N/A
A1 8385 9932 8385 8385 8076 8076 8385 8385 8385
A2 9635 9060-2 8966-6 8966-3 8386 9635 9635 9635 9635
A3 8191 8191 8191 9050-2 8191 8191 8191 9050-1 8191
A4 8465 8465 8465 8465 9081 9081 8465 8465 8465
A5 N/A 8390-2 8390-2 4100140-501 N/A N/A N/A N/A N/A
A6A1 9970 8391 7976 8391 8391 9970 N/A N/A 8391
A6A2 4100030-503 8972 8392 8392 8392 4100030-502 8392 8392 8392
A7 9134 9134 9134 9125 8361 9134 9134 9134 9134
A8 9632 8387 9632 9632 8387 9632 9632 9632 9632
A9 8388 8388 8388 8388 8388 8935 8388 8388 8388
A10 8389 8389 8389 8389 8389 8389 8389 8389 8389
A13 N/A N/A 4100020 N/A N/A N/A N/A N/A N/A
A14 N/A N/A N/A N/A N/A N/A N/A 8912 N/A
A15 N/A N/A N/A N/A N/A N/A N/A N/A N/A
A28 N/A N/A N/A N/A N/A N/A N/A N/A N/A
ROMSET 1600304 9317 1600043 9094 1600217 9666


RA6790GM CONFIGURATIONS (Cont)

ASSY RA6790/GM AD6 GM20-AD11 AD12 GM-13 GM3/GM-13 AD-16 GM-19 AD-19
A0 N/A N/A 9621 N/A 9621 N/A N/A N/A N/A
A1 8076-2 8385 8385 8385 8385 8385 8385 8385 8385
A2 9060-2 8386 9635 8966-3 8966-3 9060-2 9635 9635 9635
A3 8191 8191 8191 9050-2 9050-2 8191 4100464-501 8191 8191
A4 8465 5100004-501 8465 8465 8465 8465 4100530-501 8465 8465
A5 8390-2 8390-2 N/A N/A N/A 8390-2 4100465-501 N/A 8390-2
A6A1 7976-2 8391 8391 N/A N/A N/A 8391 7976-2 9851-2
A6A2 8392 8972 8392 8392 8392 8392 8392 8392 4100030-502
A7 9134 9134 9134 9125 9125 9134 9134 9134 9134
A8 9632 8387 9632 9632-2 9632 9632 9632 9632 9632
A9 8388 5100005-501 8388 8388 8388 8388 8388 8388 8388
A10 8389 8389 8389 8389 8389 8389 8389 8389 8389
A13 N/A N/A N/A N/A N/A N/A N/A N/A N/A
A14 8912-2 N/A N/A N/A N/A N/A N/A N/A N/A
A15 N/A N/A N/A N/A N/A N/A N/A 9669 4100361-501
A28 N/A N/A N/A 1100029-501 N/A N/A N/A N/A N/A
ROMSET 1600002 1600009 8449 1600003

Servicing

A4 ALIGNMENT[1]

Pre-Settings

-R-39 MID-RANGE
-R-47 CCW
-R-105 CW
-R-119 MID-RANGE

Steps

  1. INJECT A FREQUENCY OF 455 KHz CW AT A LEVEL OF -68dBm INTO A4J1 AND SELECT AGC SHORT & BANDWIDTH 4 (6.8 KHz FILTER) ON THE RECEIVER.
  2. ADJUST R-39 FOR -10dBm ON THE SPECTRUM ANALYZER (IF OUTPUT 50 OHMS AT REAR OF THE RECEIVER).
  3. CHANGE INPUT LEVEL TO -35dBm AND BANDWIDTH 3 (3.2 KHz FILTER) ON THE RECEIVER.
  4. CONNECT A DMM TO TP9 AND ADJUST R-47 FOR 8.5VDC ON THE DMM.
  5. SELECT MAN AGC ON THE RECEIVER AND ADJUST IF GAIN POT FOR 8.5VDC ON THE DMM.
  6. CONNECT A RF VOLTMETER WITH A HIGH-Z PROBE TO TP7.
  7. ADJUST R-105 UNTIL LEVEL STARTS TO CHANGE ON RF VOLTMETER.
  8. SELECT AGC SHORT ON THE RECEIVER AND REMOVE THE INPUT SIGNAL TO A4J1. THE DMM IS STILL CONNECTED TO TP9.
  9. ADJUST R-119 FO 10.0VDC ON THE DMM.


A7 ALIGNMENT[1]

  1. TUNE THE RECEIVER TO 29.999999 MHz.
  2. CONNECT THE POSITIVE LEAD TO DMM TO TP12 AND THE NEGATIVE LEAD TO GROUND.
  3. ADJUST L5 FOR READING OF 13.5VDC ON THE DMM.
  4. TUNE THE RECEIVER TO 00.500000 MHz.
  5. VOLTAGE ON DMM SHOULD BE GREATER THAN 3.00VDC.
  6. CONNECT THE POSITIVE LEAD TO DMM TO TP5 AND THE NEGATIVE LEAD TO GROUND.
  7. ADJUST R-16 FOR READING OF 5.2VDC ON THE DMM.


A8 ALIGNMENT[1]

  1. CONNECT A SIGNAL GENERATOR TO THE RECEIVER AND SET ITS OUTPUT AS FOLLOWS.
  2. FREQUENCY OF 29.999999 MHz & MODE CW.
  3. SET THE RECEIVER TO 29.999999 MHz, CW, BFO+1KHz AND SHORT AGC.
  4. CONNECT A FREQUENCY COUNTER TO THE AUDIO OUTPUT.
  5. ADJUST TCXO Y1 TO 1.000 KHz ON THE FREQUENCY COUNTER.
  6. CONNECT THE POSITIVE LEAD OF THE DMM TO TP8 AND THE NEGATIVE LEAD TO GROUND.
  7. RESET BFO ON THE RECEIVER TO 0.00 KHz OR BFO CENTER.
  8. ADJUST L4 FOR A READING OF 5.00VDC (+/-0.2VDC) ON THE DMM.


FORCED FILTER OPERATION[1]

1.) ENTER FORCED FILTER MODE BY PRESSING (AND HOLDING) THE LOCK KEYSWITCH , THEN MOMENTARILY PRESS THE ISB U/L KEYSWITCH. RELEASE BOTH. (THE AUX INDICATOR SHOULD ILLUMINATE ON THE AUXILIARY DISPLAY INDICATING FORCED FILTER MODE IS ACTIVE).
2.) ENTER THE DESIRED FILTER DISPLAY VALUES. THE FILTER VALUES ARE ENTERED IN ASCENDING FILTER POSITION ORDER, 1-7. (NOTE THAT A MAXIMUM OF 5 SYMMETRICAL, 1 LSB, AND 1 USB FILTERS MAY BE ENTERED. FEWER MAY BE ENTERED, DEPENDING ON THE FILTER HARDWARE CONFIGURATION).

NOTE: BLANK FILTER SLOTS SHOULD BE ENTERED SIMPLY BY PRESSING ENTER, TO MOVE PAST THE SLOT.

A.) SYMMETRICAL FILTERS: PRESS NUMERIC KEYPAD SWITCHES FOR FILTER VALUES, IN 100 Hz RESOLUTION STEPS. (FOR 400 Hz, PRESS “4". FOR 3.2 kHz, PRESS “3" THEN “2"). TERMINATE EACH FILTER ENTRY WITH ENTER.
B.) USB FILTER: PRESS THE USB KEYSWITCH, TERMINATE WITH ENTER.
C.) LSB FILTER: PRESS THE LSB KEYSWITCH, TERMINATE WITH ENTER.
D.) NULL (BLANK) FILTER SLOT: TERMINATE WITH ENTER
3.) TERMINATE FORCED FILTER MODE BY PRESSING THE ISB U/L KEY SWITCH. (NOTE THAT THE AUX INDICATOR EXTINGUISHES). NOTE THAT FORCED FILTER MODE WILL AUTOMATICALLY TERMINATE WITH THE 7th PRESSING OF THE ENTER, AS THIS WILL INDICATE TO THE RECEIVER THAT ALL FILTER SLOTS HAVE BEEN DEFINED. PRESSING ISB U/L EARLIER THAN THIS WILL TERMINATE FORCED FILTER MODE, LEAVING ALL UNDEFINED SLOTS IN THEIR ORIGINAL CONFIGURATION.


INSTALLING NEW FILTERS TO THE RA6790/GM RECEIVER[1]

Turn the power off on the front panel of the receiver. Remove the top cover to the receiver and place aside, remove the A4 filter cover if installed and place aside.

The receiver can have no more than 5 filters when the USB and LSB filters are not installed, the filter that is installed in filter slot 1 will be used as the USB and LSB filter when separate filters are not used. In most receivers a 3.24 KHz filters is installed in the first slot when the independent sideband filters are not installed. The receiver can not have more than 1 of each bandwidth filter installed. If you install 2 or more of the same filters in the receiver it will fail BITE or will not see the extra filters when BITE is run.

Install the new crystal filter ( they just plug in ) and turn the power back on to the receiver and run the BITE test by pressing and holding the LOCK and AM buttons and releasing them together on the front panel of the receiver, this will test the filters and assign them to the correct buttons on the front panel.

When installing the mechanical filters you must remove the A4 card and solder them into the A4 card with the correct coupling caps. Turn the power back on to the receiver and run the BITE test by pressing and holding the LOCK and AM buttons and releasing them together on the front panel of the receiver, this will test the filters and assign them to the correct buttons on the front panel.

Reinstall the covers when you have completed the new filter installation.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Gary R. Wingerd, Used with permission
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