Section III. OPERATION UNDER UNUSUAL CONDITIONS

TM 11-5820-509-12

Section III. OPERATION UNDER UNUSUAL CONDITIONS

or a low-pressure air jet. Be very

3-14. General

careful in cleaning ventilating openings

Radio Set AN/PRC-47 may be operated in abnormal

and accumulations that can occur in

climatic conditions provided a minimum of precautions

gear assemblies and bushings. Keep

are observed to protect the equipment. The following

the equipment as clean as possible.

paragraphs discuss operation at extremes of temperature

3-18. Emergency Operation

and humidity, during emergency conditions, and in the

presence of jamming signals.

a. Operation During Power Failure. If the primary

power source fails during operation from non-battery

3-15. Operation in Extreme Cold

power, full equipment capability can be maintained by

Extreme cold (below -40 F. ) will affect the operating

connecting the storage battery to the receiver-transmitter.

efficiency of the receiver-transmitter and can cause

However, operation with a nearly discharged storage

mechanical problems with frost buildup on components,

battery is not recommended. Short intervals of receive

brittleness in rubber jacketed conductors, binding at cable

mode operation can be obtained from a nearly discharged

connectors, dials, and switches, etc. In addition, electrical

battery, but erratic operation may result, and the transmit

difficulties may be experienced in the operation of carbon

mode should not be initiated.

microphones, charge/discharge rates of batteries, etc. If

b. Operation During Overtemperature Conditions.

possible, store the battery in a warm area, but permit the

Power amplifier tube overtemperature conditions will

remainder of the equipment to assume the ambient

interrupt transmitter operation. Press the BATTERY

temperature of the environment in which it will be

TEST pushbutton (fig. 3-1) on the RT-671/PRC-47 front

operated.

panel to bypass the overtemperature cutout temporarily.

CAUTION

Operate the transmitter as little as

The overtemperature cutout functions

possible in temperatures below -40 F.

whenever the power amplifier tube

to preclude the generation of frost on

dissipation limits are exceeded.

electrical circuits.

Replace Cover,

Recheck the settings of POWER

Panel CW-647/PRC-47 after each use

AMPLIFIER LOAD and POWER

to keep moisture out of the receiver

AMPLIFIER TUNE controls (para 3-

transmitter.

11) to assure proper output circuit

3-16. Operation in Tropical Conditions

match between the tube and the

Operation of the equipment in a tropical environment may

connected antenna. Excessive use in

result in the accumulation of fungi or condensation within

periods of unsafe internal temperatures

the plug-in modules or chassis circuits. Avoid operation

can damage the transmitter circuits.

where cooled air is permitted to blow over or around the

c. Operation During Radio Silence. When instructed

equipment.

to observe radio silence, the transmitter will not normally

CAUTION

be energized. The operator should consult local command

Check the internal circuits for fungi

directives before attempting such operation. Operation of

accumulation, and remove rust or

the receiver circuits for monitoring or broadcast reception

corrosion from electrical circuits as it

is permitted in most instances. If the transmitter must be

becomes apparent.

prepared for operation during periods of radio silence, a

3-17. Operation in Desert Conditions

dummy load (preferably shielded) should be used to tune

The extremely dry, dusty conditions present in desert

and load the circuits to the desired operating frequency.

areas and the abrasiveness of the dust can cause excessive

wear in gear trains, bushings, and bearings, can penetrate

3-19. Operation During Electronic

ventilating openings and stop airflow, and can bridge

Jamming

connectors and terminals causing low-resistance leakage

It is possible that the enemy may jam the receive channel

paths during high-humidity periods.

during real or simulated tactical operating conditions.

CAUTION

Jamming is usually evident by a strong signal on or near

Clean the interior of the equipment

the operating frequency which may, or may not, contain

often, preferably with a vacuum cleaner

3-7