4. AUDIO SPKR Switch OFF.
Headphone audio will always be active
regardless of SPKR / ON switch position.
5. Move each audio panel select switch
ON then OFF, separately, to verify
audio output from headphones for
6. Audio panel select switches Select
When selecting the desired radio for
selector, transmission capability only is
achieved. To receive, the associated audio
panel select switch must be ON.
1. Transmitter Select As desired (HF,
UHF, or VHF).
2. MIC NORMAL / OXYGEN MASK
3. MIC Switch Press to transmit.
1. Both AUDIO SPKR Switches OFF.
2. EMER / NORM AUDIO Switch
3. MIC NORMAL / OXYGEN MASK
4. INTPH HOT / OFF Select Switch
a. INTPH HOT Talk when ready.
selector to INTPH, press
switch, and transmit.
5. VOL Knob (center of transmitter
communications jack on the nose gear strut, placarded
MIC JACK, is provided for use between the ground
headphones and microphone to the aircraft interphone
system but is limited to use between the ground
personnel and the pilot position only. When in use, the
regardless of the transmitter select or interphone
switches position. The aircraft to ground interphone
system receives electrical power through, and is
protected by, the circuit breaker placarded NAV
MEMORY located on the hot battery bus.
transmitter selector to CABIN and press MIC switch to
(7) Emergency Audio Operation. Fail-safe
emergency audio is available. If either amplifier for the
dual audio panel should fail, non-amplified signals will
be directed to the headphones.
emergency audio is to pull both the pilot
and copilot audio circuit breakers.
1. EMER / NORM Audio Switch
EMER. Both systems are now in
1. AVIONICS MASTER POWER Switch
Breakers Positioned for normal
3. Aircraft dc Power OFF.
Refer to Chapter 3, Paragraph 3-4 for detailed
3C-8. ULTRA-HIGH FREQUENCY.
a. Description. The UHF (ARC-164) is a line
of sight radio transceiver which provides transmission