Section III. OPERATION UNDER UNUSUAL CONDITIONS
or a low-pressure air jet. Be very
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
panel to bypass the overtemperature cutout temporarily.
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.
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-
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
to observe radio silence, the transmitter will not normally
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
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
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.
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