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SECTION I
DESCRIPTION OF COMPLETE EQUIPMENT
1. GENERAL
Radio Transmitter BC-375-E with its associated
equipment is designed for aircraft and for applica-
tions requiring a medium power equipment with the
characteristics of strength, light weight, flexibility
and portability. The equipment is designed to provide
communication by voice, tone, or continuous-wave
telegraph over the frequency range of 150 to 12,500
kilocycles. However, only the frequencies covered by
the transmitter tuning units listed in next column
are available for use with this equipment.
Suitable tuning equipment is provided in the radio
transmitter to permit operation into a wide range of
antennas over most of the frequency range. Antenna
Tuning Unit BC-306-A may be used to extend the
range of antenna tuning for frequencies between 150
and 800 kilocycles.
1.
TU-5-B
1500-3000 kc
5. TU-9-B
7700-10,000 kc
2. TU-6-B
3000-4500 kc
6. TU-10-B 10,000-12,500 kc
3. TU-7-B
4500-6200 kc
7. TU-26-B
200-500 kc
4. TU-8-B
6200-7700 kc
Dynamotor Unit PE-73-C furnishes the power
required by the radio transmitter and operates from a
24/28 volt storage battery or other direct-current
source used in aircraft.
SECTION II
INSTALLATION
2. GENERAL
Radio Transmitter BC-375-E and associated equip-
ment are part of aircraft radio sets. Installation con-
ditions vary widely, and no detailed single set of
installation instructions can be given in this book.
However, separate instructions are furnished for each
radio set and only such general instructions as can be
followed in all installations are given in the following
paragraphs.
The requirements for shielding and bonding of
cords in aircraft installations are very rigid, so that
difficulties with extraneous pick-up from the radio
receiver side tone and radio frequency from the
power supply will be minimized.
3. RADIO TRANSMITTER BC-3 7 5-E
(Includes Mounting FT-1 5 1-A)
The radio transmitter outline dimensions and
weights are shown in 1'ig. 3.
The radio transmitter should be located in relation
to its associated equipment so that dynamotor and
antenna leads will be of minimum length. Two types
of shock-absorber mountings are available for use with
the radio transmitter: Mounting FT-151-A is a tray-
type and is part of the Radio Transmitter BC-375-E.
Mounting FT-115-B is a disposable-type. The tray-
type mounting, to which the radio transmitter is
attached by four snap-slide catches, is normally
used. The disposal mounting is sometimes added
near the top of the radio transmitter to prevent
swaying. Mounting FT-115-B consists of a rubber
button in a steel shell which may be attached to the
top, bottom, or sides of the radio transmitter. Certain
of the radio transmitter-cover fastening screws have
been placed so as to allow attachment of this mount-
ing.
The radio transmitter should not be mounted closer
than two inches from a wall, and in aircraft and
vehicular installations it is desirable that Mounting
FT-115-B be added at the top of the radio trans-
mitter to prevent excessive swaying. The power
cords should not be fastened nearer than 18 inches
from the radio transmitter. This precaution prevents
vibration from being transmitted to the unit through
the cords. It is important that sufficient space be
allowed in the front of the radio transmitter to
facilitate replacement of tubes, removal of trans-
mitter tuning units, and the making of tuning adjust-
ments. After installation has been completed and
tested, the snap-slide catches should be securely
safety-wired at the places provided.
4. DYNAMOTOR UNIT PE-73-C
The dynamotor unit should be mounted in an
accessible position to allow access to the relay-fuse
box, keeping in mind that the length of the leads from
the battery to the dynamotor unit must be as short as
practicable. This unit when operated in conjunction
with Radio Transmitter BC-375-E draws from 20 to
30 amperes. No. 6 Awg or larger conductor should
therefore be used for these leads in order to keep
the voltage drop at a minimum. Mounting FT-107
should be securely attached so that the dynamotor
unit cannot be torn loose by acceleration, vibration
or shock.
After the dynamotor unit is clamped securely to
Mounting FT-107 by means of the four snap-slide
catches, Plugs PL-59 n,nd PL-61 of the applicable
cords should be plugged in Sockets SO-39 and SO-41,
respectively on the dynamotor unit. The primary leads
from the battery should then be clamped securely to
the proper binding posts on the dynamotor unit ter-
minal board.
1
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