TM 11-6625-486-14&P
frequency meter for a zero beat in the receiver headset
3-10. Determining Frequency to Which Receiver is
or loudspeaker.
Tuned
a. Set the RANGE SW to the proper range. If the
e. If the receiver has no bfo, set the frequency
desired frequency is some harmonic multiple of the
meter FUNCTION SW to MOD and tune the frequency
fundamental frequencies covered by the filmstrip,
meter for maximum indication on the receiver S meter
consult the calibration tables to determine the filmstrip
or for maximum audio in the receiver headset or
setting (para 3-3c). If the calibration tables are not
loudspeaker.
used, divide by the appropriate number to obtain a
f. Read the frequency meter filmstrip and, if
fundamental frequency covered by the filmstrip.
necessary, locate this frequency in the FREQUENCY
b. Set the FUNCTION SW to CHK and calibrate
column of the calibration tables. At the intersection of
this frequency and the harmonics column, read the
the frequency meter at the checkpoint nearest to the
frequency being measured. If the tables are not used,
estimated fundamental frequency.
multiply by the number found in a above.
NOTE
3-11. Stopping Procedure
When performing check procedure,
do not connect the frequency meter
a. Turn the FUNCTION SW to OFF.
b. Unplug the headset from the PHONES jack.
c. Set the FUNCTION SW to OPER. Connect the
c. Disconnect the antenna and the power cable
frequency meter antenna to the ANT. connector and
and place them in the cover.
place the frequency meter antenna near the receiver.
d. Replace the front cover.
d. If the receiver has bfo, turn it on. Tune the
Section III. OPERATION UNDER UNUSUAL CONDITIONS
3-13. Operation in Desert Climates
Subzero temperatures and climatic conditions
The main problem with electronic equipment in desert
associated with cold weather may hamper the efficient
areas is the large amount of sand and dust that lodge in
operation of electronic equipment.
Follow the
moving parts and mechanical assemblies. Cleaning and
instructions and precautions given below for operation
servicing intervals shall be shortened according to local
under such condition.
conditions.
3-14. Operation in Tropical Climates
a. Keep the equipment warm and dry. If the
In tropical climates, electronic equipment may be
equipment is not kept in a heated enclosure, construct
installed in tents, or huts, or, when necessary, in
an insulated box for its protection.
underground dugouts. When equipment is installed
b. Be sure that the equipment has been warmed
below ground, and when it is set up in swamp areas
up sufficiently before use. The transistorized frequency
danger of moisture damage is more acute than normal
meter may need several minutes, depending on the
in the tropics. Ventilation is usually very poor, and the
temperature of the surrounding air.
high relative humidity causes condensation on the
c. When equipment which has been exposed to
equipment whenever its temperature becomes lower
the cold is brought into a warm room, it will sweat until it
than the surrounding air. To counteract this condition,
reaches room temperature. When the equipment has
place lighted electric bulbs under the equipment.
reached room temperature, dry it thoroughly.
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