Section IV. OPERATION UNDER UNUSUAL CONDITIONS
when equipment warms up during the day after
34. General
exposure during a cold night.
The operation of Facsimile Set AN/TXC-1(*)
may be difficult in regions where extreme cold,
heat, humidity and moisture, sand conditions,
For operation in tropical climates, the equip-
etc., prevail. In the following paragraphs, instruc-
ment may be installed in tents, huts or, when nec-
tions are given on procedures for minimizing the
essary, in underground dugouts. When equip-
effect of these unusual operating conditions.
ment is installed below ground or when it is set up
in swampy areas, moisture conditions are more
acute. Ventilation is usually very poor, and the
Subzero temperatures and climatic conditions
high relative humidity causes condensation of
associated with cold weather affect the efficient
moisture on the equipment whenever the tempera-
operation of equipment. Instructions and pre-
ture of the equipment becomes lower than the
cautions for operation under such adverse condi-
surrounding air. To minimize this condition, place
tions follow:
lighted electric bulbs under the equipment.
a. Handle the equipment carefully.
b. Keep the equipment warm and dry. Do not
allow the temperature of the fork oscillator unit
a. Conditions similar to those encountered in
to go below +32 F. Although the fork oscillator
tropical climates often prevail in desert areas.
is a sealed unit, extreme changes in temperature
Use the same measures to insure proper operation
will cause the 1,800-cps output of the fork oscil-
of the equipment.
lator to change, resulting in objectionable skew
b. The main problem arising with equipment
on the received copy. Changes in the RB +
operation in desert areas is the large amount of
voltage also will affect the output frequency of the
sand, dust, or dirt which enters the moving parts
fork oscillator. If the set is not in a heated in-
of the equipment such as motor and drum, lead
closure, construct an insulated box for the set.
screw, etc. The ideal preventive precaution is to
Keep resistor heaters (if available) turned on, pro-
house the equipment in a dustproof shelter.
vided this does not overtax the power supply. If
Since such a building seldom is available and
this method is impracticable, keep the filament of
would require air conditioning, the next best pre-
vacuum tubes lighted constantly, unless this also
caution is to make the building in which the
overtaxes the power supply. Maintain the tem-
equipment is located as dustproof as possible with
perature of the developer solutions as close as
available materials. Hang wet sacking over the
possible to +68 F.
windows and doom; cover the inside walls with
c. Locate the equipment inside a heated in-
heavy paper. Secure the side walls of tents with
closure where there is no danger of a cold draft
sand to prevent their flapping in the wind.
striking the glass tubes when a door is opened.
c. Never tie power cords, signal cords, or other
A sudden draft of cold air often is sufficient to
wiring connections to either the inside or the out-
shatter the glass envelope of a heated tube. If
side of tents. Desert areas are subject to sudden
the inclosure is so constructed that this precaution
wind squalls which may jerk the connections loose
is impossible, place a blanket or some barrier be-
or break the lines.
tween the source of the draft and the equipment.
d. When equipment which has been exposed to
d. Keep the equipment as free of dust as pos-
the cold is brought into a warm room, the equip-
sible. Make frequent preventive maintenance
ment will sweat and the lenses will become fogged
checks (pars. 40-43). Pay particular attention to
with moisture condensation. This will continue
the condition of the lubrication of the equipment.
until the equipment reaches room temperature.
Excessive amounts of dust, sand, or dirt that come
When the equipment has reached room tempera-
into contact with oil and grease result in grit,
ture, dry it thoroughly. This condition also arises
which will damage the equipment.
