Figure 4-9. 19.45 MHz Adjustment Setup #1 (1A4A3)

TM 11-5820-873-34

(a) Connect VTVM between 1A4A2-TP3 and

ground.

NOTE

The following two steps involve two

interacting components. Due to this, the

adjustments should be worked together for

the desired output.

(b) Set 100 Hz, 1 KHz and 10 KHz to 5 Adjust

1A4A2L3 for a VTVM indication of 1 95 VAC 0 25 VAC.

VTVM indication of 1.95 VAC 0.25 VAC.

(3) Remove card extender and reinstall Low Digit

Figure 4-9. 19.45 MHz Adjustment Setup #1 (1A4A3)

Generator CCA 1A4A2. Reinstall Synthesizer protective

NOTE

cover. Reinstall receiver-transmitter top cover. Remove

As adjustment progresses in the following

dummy load.

step, reduce signal generator output level to

c. Translator 1A4A3 Adjustment.

maintain VTVM indication below 100 mV

(1) Remove receiver-transmitter top cover

Remove Synthesizer protective cover. Place Translator

RMS.

1A4A3 on card extender. Connect a 50 ohm dummy load

(b) Using frequency counter, set signal

to receiver-transmitter ANT jack.

generator for 19 45 MHz Set signal generator level to 250

(2) 21 MHz Adjustment (1A4A3).

mV RMS Adjust 1A4A3L3 and 1A4A3L5 for maximum

(a) Connect oscilloscope to 1A4A3-TP4. Set

VTVM indication.

front panel VFO PULL control to in position.

(b) Adjust 1A4A3-L13 for maximum output.

Figure 4-10.

Minimum acceptable output is 800 mV peak-to-peak at a

0.0476 usec repetition rate.

(3) VFO Adjustment

(a) Connect oscilloscope to 1A4A3-TP4.

Connect frequency counter to oscilloscope vertical

amplitude output. Connect VTVM (AC) between 1A4A3-A

and ground. Pull VFO PULL control to its out position.

(b) Rotate VFO PULL control for a VTVM

indication of 7.6 VDC. Observe oscilloscope and adjust

1A4A3L23 until an oscillation is indicated on the scope.

direction and note adjustment range until oscillation stops.

Adjust L23 to approximate midpoint of available

Figure 4-10. 19.45MHz Adjustment Setup #2(1A4A3)

adjustment range.

NOTE

The following adjustment involves two

If the following indication cannot be

interacting components.

Due to this

achieved, a slight readjustment of L23 is

interaction, the adjustment of each

acceptable to obtain the correct frequency

component should be repeated until

count.

maximum output is obtained.

(d) Adjust 1A4A3L22 for a frequency counter

NOTE

indication of 21 MHz 100 Hz. Oscilloscope should

As adjustment progresses in the following

indicate a minimum sine wave of 700 mV peak to peak.

step, reduce signal generator output level to

(4) 19.45 MHz Adjustment (1A4A3)

maintain RF voltmeter indication below 100

(a) Remove Low Digit Generator CCA 1A4A2.

mV RMS.

Connect VTVM (AC) 1A4A3U3-6. Jumper 1A4A3U1-2 to

(d) Adjust 1A4A3L2 and then 1A4A3L3 for

CCA ground. Connect signal generator as shown in

maximum VTVM indication.

Figure 4-9.

(e) Connect signal generator as shown in

Figure 4-11.

4-40