Transmitter Spurious Output Adjustments

TM 11-5820-509-35

CAUTION

(2) Connect the primary power source to the

Before making the following measurements

receiver-transmitter.

and adjustments, resonate the POWER

(3) Turn on the test equipment and place the

AMPLIFIER TUNE and POWER AMPLIFIER

POWER-LIGHTS switch on the RT-671/PRC-47 to

LOAD controls on the front of the receiver-

POWER ON. Permit the equipment to stabilize for at

transmitter for maximum deflection on the

least 5 minutes before beginning the procedures listed in

the chart below.

XMTR OUTPUT meter. Use the OPR-TUNE

switch to control power amplifier plate power.

Do not permit the power amplifier to operate

c. Procedure.

for more than a few seconds at a time in the

(1) On the RT-671/PRC-47, set the

unloaded condition, serious equipment

KILOCYCLES indicator to 2400; place the CW.

damage can result.

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

(2) Place the turns-counters of POWER

circuit at the LO setting of XMTR PWR switch place the

AMPLIFIER TUNE and POWER AMPLIFIER LOAD

XMTR PWR switch to HI and peal these controls again.

controls to the settings recommended on the LOAD-

Immediately return the OPR-TUNE switch to OPR.

TUNE chart on the front of the receiver-transmitter.

Test

Radio

equipment

control

Test

Performance

Step

settings

procedures

standards

Adjust audio oscillator to

Place OPR-TUNE switch to

Adjust input attenuator on

Set 1700 Hz level for later

1700 Hz and set output

TUNE.

spectrum analyzer so that

reference.

level to 0.1 volts.

1700 Hz tone is at 0 dB

reference level.

Not more than 6 dB from

Adjust audio oscillator to

Same as step 1.

Read amplitude of 300 Hz

1700 Hz value measured

300 Hz and set output

tone on spectrum analyzer.

in step 1.

level to 0.1 volts.

Adjust audio oscillator to

Same as step 1.

Read amplitude of 3000 Hz

Not more than 6 dB from

3000 Hz and set output

tone on spectrum

1700 Hz value

level to 0.1 volts.

analyzer.

measured in step 1.

5-7. Transmitter Spurious Output Adjustments

b. Test Conditions and Equipment Connections.

(fig. 5-3)

(1) Connect the test equipment to Radio Receiver-

Transmitter RT-671/PRC-47 as show' in figure 5-3. Do

a. Test Equipment and Material.

not connect the ME-26A/U until instructed to do so.

(1) Spectrum Analyzer AN/UPM-110

(2) Converter, Hewlett-Packard K15-8551B

(2) Connect the primary power source to the receiver-

(3) Dummy Load DA-75/U

transmitter.

(4) Attenuator (see figure 5-3)

(5) Audio mixer unit (see figure 5-3)

(3) Turn on the test equipment and place the POWER-

LIGHTS switch on the RT-671/PRC-4' to POWER ON.

(6) Multimeter ME-26A/U

Permit the equipment to stabilize for at least 5 minutes

(7) Audio Oscillator TS-382/U (2 required)

before beginning the procedures listed in the chart

(8) Primary power source; 115-volt, 400-Hz,

below.

single-phase, 3 amps.

5-4