Piper ARCHER III Pilot Operating Handbook page 292

SECTION 9
SUPPLEMENT 16
SECTION 7 - DESCRIPTION AND OPERATION (continued)
ON/OFF, Pilot Intercom System (ICS) Volume Control
The GMA 340 is powered OFF when the left small knob (5) is rotated fully
CCW into the detent. To turn the unit ON, rotate the knob clockwise past the
click. The knob then functions as the pilot ICS volume control. A fail safe
circuit connects the pilot's headset and microphone directly to COM1 in case
power is interrupted or the unit is turned OFF.
Transceivers
Selection of either COM1, COM2, or COM3 for both MIC and audio source is
accomplished by pressing either COM1, MIC, COM2 MIC, COM3 MIC (14).
The activeCOM audio is always heard on the headphones.
Additionally, each audio source can be selected independently by pressing
COM1, COM2, or COM3 (13). When selected this way, they remain active as
audio sources regardless of which transceiver has been selected for microphone
use.
When a microphone is keyed, the active transceiver's MIC button LED blinks
approximately one per second to indicate that the radio is transmitting.
Audio level is controlled by the selected COM radio
volume controls.
Split COM
Pressing the COM 1/2 button (15) activates the split COM function. When this
mode is active, COM1 is dedicated solely to the pilot for MIC/Audio while
COM2 is dedicated to the copilot for MIC/Audio. The pilot and copilot can
simultaneously transmit in this mode over separate radios. Both pilots can still
listen to COM3, NAV1, NAV2, DME, ADF, and MRK as selected. The split
COM mode is cancelled by pressing the COM 1/2 button a second time.
When in the split COM mode the copilot may make PA announcements while
the pilot continues using COM1 independently. When the PA button is pressed
after the split com mode is activated the copilot's mic is output over the cabin
speaker when keyed. A second press of the PA button returns the copilot to
normal split COM operation.
REPORT: VB-1611
9-92 4 of 6
PA-28-181, ARCHER III
NOTE
ISSUED: JULY 12, 1995
REVISED: JANUARY 2, 2001