TM 11-5821-284-34
CHAPTER 3
DIRECT SUPPORT MAINTENANCE
Section I. GENERAL
Item
3-1.
Scope of Direct Support Maintenance
Test Set, Antenna
Provides control and moni-
a. This chapter provides instructions and
AN/ARM-115
toring circuits for equip-
essential illustrations covering testing and trouble-
ment under test.
shooting of the antenna. Maintenance of the antenna at
Measures servo amplifier
the direct support category is limited to replacement of
AN/USM-281
and sequencing circuit
the radome or coupler assembly.
b. Troubleshooting at the direct support
Receiver-transmitter
Provides RF source for
category supplements and includes the techniques out-
RT-8q8/ARC-181
coupler tuning.
Maintenance Kit
Connects RF source to
lined for organizational maintenance (TM 11-5821-284-
MK-1085/ARC-131
power supply and
20) and all other techniques that may be required to
coupler.
isolate a defective part. The systematic troubleshooting
Power supply. (capable
Provides +27.5 Vdc power
procedures, which begin with the operational checks at
of providing 28.0
for circuits.
an organizational category, are supplemented and
volts at 10 amperes)
extended by localizing and isolating techniques at the
Resistor, fixed carbon
Used in testing model
directed support category,
(6850-ohm, or 5600-
437S-1B antenna to
ohm, :t10X7, -watt
decrease
input
3-2.
Tools, Test Equipment, and Materials
power rating)
of servo amplifier
Required
circuit.
Tools and test equipment required for direct sup-port
maintenance are listed below:
Section II. DIRECT SUPPORT TROUBLESHOOTING
procedure
may
3-3.
Troubleshooting Procedure
eliminate the possibility
To be effective, troubleshooting must be systematic.
of further damage when
Generally, it is necessary to perform a sequence of
power is applied.
operational checks, observations, and measurements
before a defect will be revealed. If the proper sequence
is used, the trouble will be traced first to a unit, and then
WARNING
to a portion of the unit. The sequence of steps is
Be extremely careful
commonly referred to as the sectionalization and
when working around
localization of a trouble.
the antenna or the
a. Sectionalization. A defect in radio set or
antenna
terminals.
communication system should first be sectionalized to a
RADIO FREQUENCY
particular unit. This normally is accomplished through
HIGH
VOLTAGES
visual checks and meter readings during system
EXIST
AT
THE
operational testing.
TERMINALS. Operator
b. Localization. When the defective unit in a
and
maintenance
system has been isolated to an antenna, localize the
personnel should be
trouble to a particular portion of the antenna by
familiar
with
the
inspection or by performance testing procedures.
requirements of TB SIG
291 before attempting
CAUTION
installation or operation
If
possible,
obtain
of the
operational symptoms
before applying power
to an antenna.
This
3-1
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