TM 1-1510-218-10
3B-3
1. PILOT/COPILOT AUDIO OFF Switches
2. Pilot's/Copilot's Transmitter Select Switch
3. Pilot's/Copilot's AUDIO SPKR / OFF Switch
4. Pilot's/Copilot's Audio VOLUME Controls
5. Pilot's/Copilot's VOICE / BOTH / RANGE
Switch
6. MKR BCN 1 & 2 HI / LO / TEST Switch and
VOL Control
7. AUDIO EMER / NORM Switch
Figure 3B-1. Audio Control Panel
c. Normal Operation.
(1) Turn-on Procedure. The a udio control
panel is on whenever electrical power is applied to the
aircraft and the AVIONICS MASTER POWER switch
is ON.
(2) Interphone Operating Procedure.
1. Transmitter selector switch – PA.
2. Microphone switch – Press, listen for
sidetone.
3. VOLUME control – Adjust sidetone
and
interphone
audio
level
in
headphone.
(3) Navigational Aid and Receiver Monitoring
Procedure.
1. Inter-communication switches – As
required.
2. VOLUME control – Adjust volume
control of system being monitored.
(4) Transmitting Procedure.
1. Transmitter selector switch – As
required.
2. Microphone switch – Press, listen for
sidetone.
3. Applicable transceiver volume control
– Adjust for comfortable audio level.
d. Emergency Operation. An audio fail-safe
system is provided for use in the event of an audio
amplifier failure. If an audio amplifier fails, receiver
audio bypasses the amplifier and is applied directly to
the headsets. No audio will be available to the
overhead speakers.
3B-7. UHF COMMAND SET (AN/ ARC-164).
a. Description. The UHF command set
provides two-way Amplitude Modulated (AM) voice
communication within the frequency range of 225.000
to 399.975 MHz for a distance range of approximately
50 miles line-of-sight. Channel selection is spaced at
0.025 MHz intervals. Additionally, a separate receiver
is incorporated to provide monitoring capability for the
UHF guard frequency (243.0 MHz). The audio output
of the UHF set is applied to the audio control panel
where it is made available to the headsets and
speakers. The UHF command set is protected by a
