TM 55-1510-222-10
Figure 3-1. Audio Control panel (Typical Pilot, Copilot) (499-0099)
(3)
NAV receiver audio monitor controls.
Combination volume control and on-off switch for NAV
receivers.
(a)
NA V-A. Connects user's
headset to audio from VOR-1, VOR-2 or marker beacon
set in use.
(b)
NAV-B.
Connects
user's
headset to audio from TACAN or ADF set in use.
(4)
Microphone impedence select switch.
The microphone impedence select switch uses a two
position rotary switch, which enables selection of an
interface circuit with the best impedence match to the
microphone in use.
(a)
The
impedance
of
MIC
1
position is 5 Ohms.
(b)
The
impedance
of
MIC
2
position is 150 Ohms.
(5)
Transmitter-interphone
selector
switch. Connects microphone and headset to selected
radio transmitter or interphone line, routing received
audio to headset. Bypasses control of respective
receiver audio switch.
(a)
PVT. Position not used.
(b)
ICS. Activates pilot-to-copilot
intercom.
(c)
No. 1. Permits transmission
and audio reception from VHF-AM #1 transceiver.
(d)
No. 2. Permits transmission
and audio reception from FM/AM #2 transceivers.
(e)
No. 3. Permits transmission
and audio reception from UHF transceiver.
(f)
No. 4. Permits transmission
and audio reception from HF/VOW transceivers.
(g)
No. 5. Permits transmission
and audio reception from BU VOW transceiver.
(6)
ICS select switch. Controls activation
of microphones.
(a)
HOT MIC. Admits speech to
interphone system without need to key microphone
switch.
3-3
