Operation - Garmin GMA 340 Pilot's Manual

On.
Off. and Failsafe
Operation
The
GMA 340
is
powered
off
when
the
lelt smallknob
(5,
7)
is
rotated
frlly
CCW into
the detent.
To
tum
the
unit
on rotate the
knob
clockwrse past the
click.
The left small
knobs
also
lunctions
as
the
pilot
or
copilot's
ICS
volume control
on the
appropriate
unit.
A
failsafe
circuit connects the pilot's headset
and
microphone directly to
COM I in
case
the
power
is
intemrpted
or the
unit
is
tumed
off.
Lighting
LED
Button annunciator and
markerbeacon lamp intensity
are
controlled
automatica\by
a
bulhin
photocell
on the
front panel. Nomenclature backlighting
is
controlled by
the aircraft
dimmer buss.
Transceivers
Audio level is controlled
by
the selected
C)M
radio volume control.
SelectionofeitherCOM
I,COM
Z,orCON4
3(13)forbothMlCandaudiosourceisaccomplished
by
pressrng
either
COM
I
N4lC, CON4 2 N4lC,
or
COM
3
MIC (14).
The active com audio
rs
always
heard
on
theheadphones.
Additiona\
each
audio source canbe
selectedindependentlybypressrry
COM
1,
COM 2,or COM
3
(13)
When
selected
in this way,they
remain
active
as
audio sources regardless
olwhich
transceiver has
been selected
formicrophone
use.
When
a
microphone
is
keyed, the active [ransceiver's
MIC button LED
blinks
appro]omately
once
per
second
to
indicate that the radio
is
transmittlng.
Split
COM
(Not Available on
Dual
ADFI
Pressingthe
CON{
l/2
button (15) actlates
the
Sp1lt
COM function. When
this mode
is
active,
COM I
is dedicated
sole1y
to
the
pilot lor
Ml0audio
while
COM
2 is
dedicated to the copilot for
MIO
audio.
The
pilot
and
copilot
can
srmuhaneously transmit in
this
mode
over
separate
radios. Both pilots
can
still
listen to
COM
3,
NAV
l,
NAV
2, DI\4E,
ADE
and
MKR
as
selected. The
Split COM mode is
cancelled by
pressrng
the CON4 1/2
button
a
second time.
When
rn the
Split
COM
mode
the
copilot may make
PA
announcements whrle
the
pilot
continues
usrry
COM
I
independently When
the
PAbutton
is
pressed after the Split
COM mode
is
activated, the
copilot's
mic
is
output over the cabrn speaker
when keyed.
A second prcss
of
the
PA
button returns the
copilot
to
normal spht COM operation.
lf
the
C)M
radios
utilize
a
"transmit interlock"
system, the
Split
C)M
function may require
that this
feature is
enabled.
Refer
to
the radio's
installation manual for
guidance.
GARMIN makes no
expressed
or implied
guarantees regarding the suitability
of
the
Split
C)M
feature
in a given
installation,