Figure 4-17. VHF VCO CCA Adjustment Points

TM 11-5820-873-34

Figure 4-17. VHF VCO CCA Adjustment Points

1. Set front panel 1 MHz frequency selector to 0 Adjust

Inject + 1.95 VDC, from a bench power supply, at

1A4A5L4 for 101.75 0.2 MHz.

1A4A5-4. Connect a 47 ohm, 1/2 or 1/4 watt, resistor

between 1A4A5-2 and ground.

only to 9 Adjust 1A4A5C27 for 110.75 0.75 MHz.

(b) Set front panel 10 MHz frequency

(d) Repeat step (b) and (c) above until both

selector to 1. Set front panel 1 MHz frequency selector

frequency

adjustments

are

within

tolerance

to 6. Adjust 1A4A5L12 for approximately 225 mV RMS.

simultaneously.

Minimum acceptable output is 100 mV RMS.

(4) Band "2" Adjustment

(a) Connect frequency counter to 1st Local

selector set to 0. Record RF voltmeter reading with 10

Oscillator output 1A4A5J1. Inject + 1.95 VDC, from a

MHz frequency selector set to 2 and 1 MHz frequency

bench power supply, at 1A4A5-4.

selector set to 9.

(b) Set front panel 10 MHz frequency

(d) Readjust 1A4A5L12 as necessary so the

selector to 2. Set front panel 1 MHz frequency selector

VTVM readings are within 3 dB of each other in steps

to 0. Adjust 1A4A5L7 for 111.75 0.2 MHz

(b) and (c) above.

(e) Remove 47 ohm resistor between

only, to 9 Adjust 1A4A5C38 for 120.75 0.75 MHz.

1A4A5-2 and ground.

(d) Repeat steps (b) and (c) above until both

(6) Remove dummy load.

Reinstall VHF

frequency

adjustments

are

within

tolerance

Divider CCA 1A4A4. Reinstall Synthesizer protective

simultaneously.

cover.

Reinstall receiver-transmitter bottom cover.

(5) 1st Local Oscillator Output Level

Reinstall receiver-transmitter top cover. Reinstall front

(a) Connect VTVM (AC) (w/50 ohm

panel.

termination) to 1st Local Oscillator output 1A4A5-J1.

4-43