Garmin GMA 347 Pilot’s Guide
190-00325-00 Rev. A
4
Description
INTRODUCTION
The Garmin GMA 347 is an audio control panel and mark-
er beacon system. Pushbutton keys control audio selection of
COM, NAV, telephone and intercom. With the exception of
the
PLAY
key, LED annunciators indicate when a key function
is selected. Annunciator brightness is adjusted automatically
by photocell dimming. LED-illuminated key brightness is
adjusted by the radio dimming bus control. A failsafe circuit
connects the pilot’s headset and microphone directly to COM 1
in case power is interrupted or the unit is turned off.
The GMA 347 includes a six-position intercom system
(ICS) with electronic cabin noise de-emphasis and two stereo
music inputs. Two volume controls, one for the pilot and a
combined copilot/passenger control, set intercom audio level.
The intercom provides four selectable modes of isolation (All,
Crew, Pilot, Copilot). A pilot-selectable cabin speaker output
is used to listen to selected aircraft radios or to broadcast PA
announcements. MASQ
TM
(Master Avionics Squelch) process-
ing reduces ambient noise from the avionics inputs.
Each microphone input has an automatic squelch threshold.
Manual squelch is available by pressing the Pilot side
VOL/SQ
knob. When the MAN SQ annunciation is lit the large squelch
knobs control pilot and copilot/passenger squelch threshold.
Turning either knob clockwise increases the squelch threshold
level, turning counterclockwise decreases the level.
The GMA 347 provides a digital recorder that can play back
two and a half minutes of COM audio. Recording is automatic
when a COM signal is received. Playback is controlled by
pressing the
PLAY
key or a remote mounted switch. Playback
can be stopped by pressing the
MKR/MUTE
key.
Upon installation, the unit may be configured in various
ways depending on the aircraft type and the needs of the
pilot. See the configuration list at the end of this manual.
Contact a Garmin-authorized service center for details and
assistance in altering the configuration settings.
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