Figure 5-3 Transmitter Spurious Outputs Adjustment. Equipment Setup

TM 11-5820-509-35

Figure 5-3 Transmitter Spurious Outputs Adjustment. Equipment Setup

for more than a few seconds at a time in the

c. Procedure.

unloaded condition, serious equipment

(1) On

RT-671/PRC-47,

set

the

damage can result.

KILOCYCLES indicator to 2400; place the CW-

FSK/VOICE switch to VOICE, the XMTR PWR switch to

LO, and the OPR-TUNE switch to OPR.

(3) After resonating the power amplifier plate

circuit at the LO setting of XMTR PWR switch, place the

(2) Place the turns-counters of POWER

XMTR PWR switch to HI and repeat the peaking

AMPLIFIER TUNE and POWER AMPLIFIER LOAD

procedure.

controls to the settings recommended on the LOAD-

TUNE chart on the front of the receiver-transmitter.

(4) Return the OPR-TUNE switch to OPR.

(5) Adjust the spectrum analyzer to 2400

CAUTION

kHz; set the audio oscillators to 900 Hz and 2800 Hz

Before making the following measurements

respectively at an output level of 0.1 volts per tone.

and adjustments, resonate the POWER

AMPLIFIER TUNE and POWER AMPLIFIER

NOTE

LOAD controls on the front of the receiver-

Adjust the driver bias between-30 and -55

transmitter for maximum deflection on the

volts dc and the power amplifier grid bias

XMTR OUTPUT meter. Use the OPR-TUNE

between-105 and - -1 1 5 volts dc to obtain the

switch to control power amplifier plate power.

minimum distortion products.

Do not permit the power amplifier to operate

Test

Radio

equipment

control

Test

Performance

Step

settings

procedures

standards

Place CW-FSK/VOICE switch to CW-FSK. Measure third-order

Not less than 30 dB down

Switch to CW-FSK

distortion product above

from peak envelope power

the passband (above

output level.

2404.6 kHz).

Same as step 1.

Measure third-order

Same as step 1.

distortion product below

the passband (below

2399.0 kHz).

Reduce output of 900-Hz

Same as step 1.

Measure carrier amplitude

Not less than 40 dB down

Oscillator to zero.

(2400.0 kHz).

from peak envelope power

output level.

Same as step 3.

Same as step 1.

Measure amplitude of 2800

Not less than 60 dB down

Hz sideband that occurs

from peak envelope power

below the carrier (2397.2

output level.

kHz).

5-5