Section III E

E. RX-TX Bd Alignment (7H016) (Transmitter)

1. Connect a wattmeter and 50,n. dummy load to the radio's antenna connector. See step 6 of General tuning procedure section.

2. On channel 20, peak L206 and L207 for maximum 16.8 MHz voltage at TP 4. At least 8v p-p should be present.

3. With a 20mv p-p 1 KHz audio input at the radio mic connector (MIC GAIN full CW and COMP IN) on LSB transmit, set 8274 RFL for 0.5v p-p audio at TP 1. Vary the audio input level 20db above and below the 20mv level to verify proper ALC operation. At a point below the 20mv level, the audio at TP 1 will start to drop, and above that the audio should limit at 0.6v p-p.
4. Remove one end of the cable which goes between the RX-TX and SMO board that is labeled SMO. Set 90°/, 1 KHz AM at TP 2 on RT board with 8699 (CAR ADJ) on SMO board. Be sure audio is in ALC limiting when 8699 is adjusted. Always use an oscilloscope to adjust the modulation, not a meter. 8e-connect the SMO cable.

5. Peak L204, L202, L203, L205, and L201 in that order for maximum power output on CH 20. Adjust 8205 to maintain 4 watt carrier output. Check output power balance on Ch 1, 20, and 40. If this power varies more than 0.5 watt from Ch 1 to 40 complete the following. Slightly adjust L204 for maximum power on Ch 1 and L205 on Ch 40. Check power balance. Re-check 4 watt level and adjust 8205 if required.

6. Turn to LSB mode and check power level with limiting 1 KHz modulation. It should be at least lOw.

7. Set front panel meter to read 4w with no modulation on AM, Ch 20 using TX MTR CAL pot 8557 located on the Interface Board (73043). There is a small hole through the circuit board to allow adjustment from the back side.

8. Remove audio generator, and using a microphone check the whistle and speech modulation waveforms on AM, LSB, and USB. Be sure AM carrier level is 4w and adjust 8699 (CAR ADJ) for 90% whistle modulation on AM, if necessary. Check whistle up power on LSB and USB (low min). Also check proper meter operation on all modes. The meter should always go upward with modulation.

9. Return to Section C. Interface Board (7H043) Adjustment.

(RECEIVER)

10. Connect a signal generator to the radio antenna connector. Be sire to remove microphone or transmit keying circuits to avoid possible damage to generator.

11. On channel 20, tune L208, L209, L214, L211, L212, and L213 on LSB for peak S-meter reading. Adjust generator frequency to keep audio output at 1KC. Use 8286 (SM) to keep the S-meter at S-9 and 8306 (IF AGC) to keep the 1KC audio on TP 8 at 3.Ov p-p. Be sure audio is unsquelched. Keep reducing the rf generator input level as the receiver is tuned, to just barely keep the level in full AGC. Full AGC is usually at signal levels above 10 UV. For -60dbm signal level, set 3.Ov p-p at TP 8 with 8306 (IF AGC). Rotate clarifier control and verify its operation by noting a change in receive audio frequency.

12. Check USB receive and clarifier operation for proper sensitivity and operation. Do not retune the receiver on USB.

13. In the AM rcv mode, set 2.v p-p at TP 8 using 8314 (AM). RF generator should be at 1KC, 50% modulation AM with a -60dbm (220 UV) signal level.

14. Check squelch operation at TP 8. Rotation of the front panel squelch control should cause the audio at TP 8 to be cut off.

15. Apply a -50dbm (700uv) signal. Rotate (R292) RF AGC from CCW position to CW while observing front panel "S" meter. A 1/16" or more deflection of the pointer indicates proper operation of the RF attenuator circuits. Set RF AGC (R292) at TP 5 for 1.5 vdc with -50 dbm on LSB receive with 1.KHz audio out.

16. Check R/T switching at TP 5. It should be +8 VDC on xmt and 0 VDC on receive (with no rcv signal).

17. Set S-meter to S-9 with a 50 uv (-73 dbm) signal generator level on LSB receive, with 1 KC audio out using 8286 (SM).