Microphone Amplifier Gain Adjustment

TM 11-5820-509-35

Figure 3-108. Transmitter Sidetone Adjustment, Test Equipment Setup.

3-25. Microphone Amplifier Gain Adjustment

(b)

CW-FSK/VOICE switch to CW.

(fig. 3-94, 3-105, 3-109)

(c)

OPR-TUNE switch to OPR.

a. Preliminary Procedures.

(d)

XMTR PWR switch to OFF.

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

(e)

POWER-LIGHTS switch to POWER

case using the procedures of paragraph 3-11.

ON.

(2) Connect the primary power source to the

b. Adjustment Procedures.

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

(1) Connect the oscilloscope to chassis

4 7.

connector J2-22 {fig. 3-105) and adjust A1R27 (fig. 3-

{3) Connect the audio oscillator, oscilloscope,

94) to obtain an oscilloscope amplitude of 3.5 volts

multimeter, and blocking capacitor to the receiver-

peak-to-peak.

transmitter as shown in figure 3-109.

(2) Return the POWER-LIGHTS switch to

(4) Set the audio oscillator to 1700 Hz and

POWER OFF and disconnect the test equipment.

adjust the output level at pin C of the AUDIO connector

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

to 0.1 volt rms.

using the procedures of paragraph 3-11 if no further

(5) On the front panel of RT-671/PRC-47, set

adjustments are required.

the controls as follows:

(a) KILOCYCLES indicator to any

Figure 3-109. Microphone Amplifier and VOX Gain Adjustments, Test Equipment Setup.

3-26. Transmitter VOX Gain Adjustment

been internally connected for VOX

(fig. 3-94, 3-95)

operation (para 2-1b).

NOTE

Perform this adjustment routine only

on Radio Set AN /PRO-47 that has

3-127