b. Controls and Functions, Pilot's Audio
Control Panel. Refer to Figure 3A-1.
1. Transmitter Selector Switch
2. VOL Control
3. ICS # 1 / OFF Switches
4. AUDIO SPKR / PHONE Switch
5. AUDIO NORM / EMER Switch
6. FILTER Switches
7. CABIN ADF-1 / OFF / ADF-2 Switch
8. MKR BCN VOL Switch
9. MKR BCN HI / LO Switch
10. HF VOL Control
Figure 3A-1. Pilot's Audio Control Panel
(1) Transmitter Selector Switch. Controls
operation of selected system.
(a) HF. Permits reception of audio from
the HF transceiver and routes key and microphone
signals to the HF transceiver.
(b) UHF. Permits reception of audio from
the UHF transceiver and routes key and microphone
signals to the UHF transceiver.
(c) VHF-1. Routes key and mic signals
to the #1 VHF transceiver.
(d) VHF-2. Routes key and mic signals
to the #2 VHF transceiver.
(e) INTPH. Permits transmission and
reception of interphone signals.
(f) CABIN. Removes ADF audio from
cabin speakers and allows the pilot to talk to cabin
(2) VOL Control. Controls audio volume.
(3) ICS # 1 / OFF Switches. Permits
monitoring by pilot of selected audio regardless of
position of transmitter selector switch.
(a) HF. Permits monitoring of HF audio.
(c) VHF 1. Permits monitoring of
(d) VHF 2. Permits monitoring of
(e) VOR 1. Permits monitoring
(f) VOR 2. Permits monitoring of
(g) ADF 1. Permits monitoring of
(h) ADF 2. Permits monitoring of
Determines where selected audio will be heard.
(a) SPKR. Allows selected audio to be
heard via the speaker.
(b) PHONE. Allows selected audio to be
heard via the phone.
(5) AUDIO NORM / EMER Switch. Controls
routing of received audio signals.
(a) NORM . Routes audio signal through
amplifier to speaker or headphone.
(b) EMER. Audio signal bypasses
amplifier. Applies audio signal to headphone only.
Either the ADF or VOR switch must be in
the OFF position for the other switch to
(6) FILTER Switches.