Balanced Modulator Adjustments

TM 11-5820-509-35

Figure 3-111. Temperature Compensated Oscillator Rotor Frequency Adjustment Test Equipment Setup.

(a)

KILOCYCLES indicator to 2000.

b. Alignment Procedures.

(b)

CW-FSK/VOICE switch to VOICE.

(c)

OPR-TUNE switch to OPR.

(1) Measure the output frequency using the

frequency counter connected to A6J4.

(d)

XMTR PWR switch to LO.

(2) If the output frequency does not read

(e)

POWER-LIGHTS switch to POWER

exactly 5000,000.0 Hz, adjust A6C1 (fig. 3-99) ON.

CAUTION

until the frequency counter reads

Do not permit the OPR-TUNE switch

correctly.

to remain in the TUNE position for

(3) Return the POWER-LIGHTS switch to

more than a few seconds at a time

POWER OFF and disconnect the test equipment.

while the POWER AMPLIFIER TUNE

and POWER AMPLIFIER LOAD

(4) Return the RT-671/PRC-47 to its case

using the procedures of paragraph 3-11 if no further

controls are being adjusted. Circuit

adjustments are required.

damage can occur.

3-29. Balanced Modulator Adjustments

(fig. 3-112)

(5) Set the POWER AMPLIFIER TUNE and

a. Preliminary Procedures.

POWER AMPLIFIER LOAD controls to the turns-

counter values shown on the LOAD-TUNE chart.

(1) Remove the RT-671/PRC-47 from its

case using the procedures listed in paragraph 3-11.

(6) Place the OPR-TUNE switch to TUNE;

quickly peak the POWER AMPLIFIER TUNE and

(2) Connect the primary power source to the

POWER AMPLIFIER LOAD controls for maximum

POWER connector on the front panel of RT 671 /PRC-

deflection on the XMTR OUTPUT meter. Immediately

47.

return the PPR-TUNE switch to OPR.

(3) Connect the dummy load to the receiver

transmitter; extend Amplifier-Modulator AM 3507/PRC-

NOTE

47 (A8A2) from the main chassis of RT 671/PRC-47

Adjust M ADJ control as required to

using extender cable no. 4 from Cable Assembly Set

maintain the XMTR OUTPUT meter

AN /PRA-4; then remove the module side cover to

expose the adjustment screw in the top of transformer

pointer on a useful portion of the

T2.

scale.

(4) Set the front panel controls of RT-

671/PRC-47 as follows:

(7) Place the XMTR PWR switch to HI and

repeat step (6).

3-130