TM 55-1510-222-10
Section II. COMMUNICATIONS
3-4.
DESCRIPTION.
The communications equipment group consists of
an interphone system connected to individual audio
control panels for the pilot and copilot which interface
with VHF, UHF, BU VOW, VHF FM and HF
communication units.
3-5.
MICROPHONES, SWITCHES AND JACKS.
Boom and oxygen mask microphones can be
utilized in the aircraft.
a.
Microphone Switches. The pilot and copilot
are
provided
with
individual
microphone
control
switches, placarded INTPH-XMIT-MIC, attached to their
respective control wheels. A foot-actuated microphone
switch is also positioned in the floorboards forward of
each pilot's seat.
b.
Controls and Functions.
(1)
Microphone control wheel switches
(fig. 2-20). Keys selected facility.
(a)
INTPH
(depressed
to
first
detent). Keys interphone facility, disregards position of
transmitter selector switch.
(b)
XMIT (depressed full down).
Keys facility selected by transmitter select switch.
(2)
Floorboard transmit switches. Keys
facility selected by transmitter select switch.
(a)
Held depressed. Keys facility
selected by transmitter select switch.
(b)
Released. Unkeys selected
transmitter.
c.
Microphone jack selector switches. Two
switches, placarded MIC HEADSET OXYGEN MASK,
are located in the extreme left and extreme right of the
instrument panel (fig. 2-14). These switches provide a
means of selecting whether the headset microphone
jack or the oxygen mask microphone jack is connected
to the audio system.
d.
Controls and Functions.
(1)
MIC HEADSET OXYGEN MASK
switch. Selects microphone jack 'to connect to audio
system.
(a)
MIC
HEADSET.
Connects
headset microphone to audio system.
(b)
OXYGEN MASK. Connects
microphone in oxygen mask to audio system.
3-6.
AUDIO CONTROL PANELS.
a.
Description. Separate, but identical audio
control panels (fig. 3-1), serve the pilot and copilot.
The controls and switches of each panel provide the
user with a means of selecting desired reception and
transmission sources, and also a means to control the
volume of audio signals received for interphone,
communication and navigation systems. The user
selects between the UHF, VHF, BU VOW, VHF FM and
HF transceivers. The audio control panels are protected
by respective 2-ampere AUDIO PILOT and AUDIO
COPILOT circuit breakers located in the overhead
circuit breaker panel (fig. 2-6).
b.
Controls and Functions.
(1)
Master
VOL
control.
Controls
sidetone volume to headset. Also serves as final
volume adjustment for received audio from any source
before admission to headset.
(2)
Radios audio monitor controls. Each
is a combination rotary control, on-off push-pull switch
permitting
both
receiver
selection
and
volume
adjustment.
(a)
No. 1.
Connects user's
headset to audio from VHF-AM #1 transceiver No. 1.
(b)
No. 2. Connects user's
headset to audio from the FM/AM #2 transceivers.
(c)
No. 3.
Connects user's
headset to audio from UHF transceiver.
(d)
No. 4.
Connects user's
headset to audio from HF/VOW transceivers.
(e)
No. 5.
Connects user's
headset to audio from BU VOW transceiver.
3-2
