Section II. SYSTEM APPLICATION TROUBLESHOOTING

(3) Intermittent troubles. If intermit-

associated technical manuals are also

listed.

tent troubles are present, they may

often be made to appear by tapping

or jarring the equipment. Check the

Technical manual

Test equipment

wiring and connections to the sub-

TM 11-5527

Multimeter TS-352/U . . . . . . . . . . .

units of the radio set.

TM 11-6625-274-

Electron Tube Test Set TV-7/U . . .

d. Voltage and Resistance Measure-

ments. Voltage and resistance measure-

TM-2661

Electron Tube Test Set TV-2/U . . .

TM 11-2684A

Audio Oscillator TS-382A/U . . . . . .

ment tests can be made by the use of

TM 11-5030

Signal Generator TS-497A/URR . . .

adapter sockets for all vacuum tubes ex-

TM 11-5094

Frequency Meter AN/URM-79. . . . .

cept V104, V105, and V106. Remove the

TM 11-5095

Frequency Meter AN/URM-80 . . . . .

Frequency Meter AN/URM-81 . . . . .

TM 11-5096

screws (1) (fig. 68); remove the cover

Analyzer, Spectrum TS-723A/U . . .

TM 11-5097

plates to gain access to V104, V105, and

Frequency Meter AN/URM-32 . . . .

TM 11-5120

V106 (fig. 70). Figure 83 shows the sub-

Oscilloscope AN/USM-50 . . . . . . . .

TM 11-5129

TM 11-5133

Radio Frequency Wattmeter AN/

unit locations. Use the voltage and resist-

URM-43A.

ance diagrams (fig. 84 through 89) to find

R.F. Signal Generator Set AN/

TM 11-5551-D

the normal readings for the rt unit, and

URM-25D.

TM 11-6625-

Electronic Voltmeter ME-30B/U . .

compare them with the readings taken.

320-12

Frequency Meter AN/USM-26 . . . . .

TM 11-5057

94. Test Equipment Required

Attenuator, Variable CN-318/U.

Linear Detector, Hewlitt Packard

The following chart lists the test equip-

Model 420A or equivalent.

ment required for troubleshooting Radio

Multimeter ME-26 B/U . . . . . . . . . . .

TM 11-6625-

200-12

Sets AN/VRC-24 and AN/TRC-68. The

Section II. SYSTEM APPLICATION TROUBLESHOOTING

or remote cable. Use figure 35 as a guide

95. Defective Retransmission Operation

in troubleshooting the retransmission cir-

With Radio Sets AN/GRC-3 Through

AN/GRC-8

cuits.

a. General. When Radio Set AN/VRC-

b. Conditions for Tests. With the equip-

24 operates normally on transmit and

ment connected for normal operation as

receive for local and remote positions (and

shown in TM 11-5820-222-10, perform all

the AN/GRC-3 through AN/GRC-8 oper-

checks outlined in the following chart to

ates normally as a separate radio set),

sectionalize trouble to the faulty unit.

failure to retransmit may be caused by a

faulty CX-4498/U, faulty rt unit, faulty

c. Retransmission Troubleshoot-

MT-1436/U, Radio Set Control C-1439/U,

ing Chart (fig. 35).

Item

Indication

Probable trouble

Procedure

Signal received on the AN/

Faulty wire in, or connector

Remove rear cover on MT-1436/U (fig.

VRC-24 (VRC-24 CALL

on, CX-4498/U.

46) and check continuity.

LIGHT on and signal

Faulty wiring in the MT-

Make resistance and continuity measure-

heard in headset or

1436/U, rt unit main

ments to isolate trouble in faulty audio

speaker), but RT-66/

frame, or audio amplifier

amplifier modulator subunit.

GRC, RT-67/GRC, or

modulator, or faulty R814.

Check resistance and continuity in main

RT-68/GRC transmitter

frame or Mounting MT-1436/U (fig.

not keyed.

35, 126).

AN/GRC-5 transmitter does

Defective wiring in MT-1436/

Remove rear cover on MT-1436/U (fig.

not modulate on retrans-

U, main frame, or relay

46) and check continuity.

unit; defective R615 or

mit function. (No AN/

Make resistance and continuity measure-

VRC-24 fixed level audio

FL26.

ments to isolate trouble in relay sub-

output present.)

unit (fig. 66 and 67 and para 113).