RA6790~GM

Alignment

ALIGNMENT FOR THE RA6790/GM RECEIVER

A4 ALIGNMENT

Pre-Settings

R-39 MID-RANGE

R-47 CCW

R-105 CW

R-119 MID-RANGE

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

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

A8 ALIGNMENT

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

GARY E. WINGERD 9107 JORDAN RD. FAIRPLAY, MD. 21733 301-582-2424 gewingerd@netzero.com