Section III C

C. Interface Board (7H043) Adjustment

1. This board contains control, metering, and audio processing circuitry.

2. Connect an audio oscillator to the microphone input connector at 20mv p-p 1Kz. Measure the voltage at TP 1 which should be .42v pp.

3. Turn MIC GAIN control full clockwise and measure 3.2v p-p at TP 2.

4. Move scope to TP 3 and observe 1.0v p-p of compressed audio.

5. With the scope at TP 4 the level should be 0.5v p-p with the front panel switch set to the COMP IN position and .57v p-p in the OUT position.

6. Connect pins 3 and 4 of the microphone connector together. This places the radio in the transmit mode. The front panel LED should be lit.

7. With the radio in transmit, check the voltage at the collector of Q509 which should be 9.9 volts (Pin 8 on 7H016 comb).

8. After completion of the above procedures go to Section D. SMO Bd (7H042)alignment procedures. The remaining steps in this section are completed after alignment of 7H016.

9. Using an external wattmeter of known accuracy set the front panel meter to read the same power (4 watts typical) with no modulation on AM, Ch 20 using TX MTR CAL pot 8557 located on the Interface Board (7H043). There is a small hole through the circuit board to allow adjustment from the back side.

10. Check for proper operation of the VSWR meter circuitry. Place front panel switch to VSWR CAL, turn control for full scale deflection on front panel meter (CAL). Switch to VSWR READ; should be 1.5 or less for most good loads.