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2. Adjust L107 [refer to the diagram above – The Synthesizer Board] such that the multimeter reading is
centered on 3.5 Volts for all programmed channels.
3. Adjust CV102 for maximum output into the power meter. output should be 20mW to 40mW
VHF). Release the PTT button.
4. Connect J366 to P366. Connect a 50Mhz power meter to the antenna output. Set RV502 on the Power
Amplifier PCB fully clockwise. Set the power supply to 13.8 Vdc.
5. Operate the PTT and adjust CV501, then CV502, and finally CV503 for maximum power output.
Repeat the adjustment of CV501, then CV502 and CV503 for maximum power.
6. Adjust RV502 to obtain Po = 25W (High Power position). Note that the power rises slightly as the unit
heats up, so adjust for 23 - 24W when cold.
7. If "low power" output is required, short P302 to P303 on the control unit and adjust RV501 for
required output.
8: Also check at the lowest & highest frequencies – channel 19 [52.500Mhz] an channel 38 [53.975Mhz].
Transmitter Audio Adjustments:
1. Adjust audio oscillator for a 600 ohm output level of 30mV rms.
2. Switch on the PTT and measure the deviation. Vary the frequency from 500Hz to 3KHz and find the
maximum deviation. Adjust RV101 for +- 5KHz maximum, testing for positive and negative
deviation. Slight adjustment may be made to L101 and L102 (for VHF) to obtain optimum symmetry
and distortion.
3. Reduce the audio oscillator to 3mV rms at 1KHz.
4. Adjust RV102 for +-3KHz deviation. If necessary, repeat steps 1 and 2 above.
Midland 70-066 low Band Conversion to 6 Meters: Transmitter PA Part 4 Ver 2.2 21Nov09 Page 15
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