Garmin GMA 340 Manual

GMA 340
A. L' D I O PA I\ I L
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Front Panel Controls
Marker Beacon
Marker Beacon
Marker Beacon
Marker Beacon
Passenger
].1. Passenger Address (PA) Function Button
I2. Speaker Function Button
Transceiver Audio Selector Buttons (COMl, COM2, COM3)
Transmitter (Audio/Mic) Selection Buttons
Split COM Buuon
Aircraft Radio Audio Selection Buttons (NAVI, NAV2, DME, ADF)
I7. Annunciator Test Button
18. Locking Screw Access
19. Photocell - Automatic Annunciator Dimming
On, Off, and Fail-Safe Operation
The GMA 340 is powered off when the left small knob (5) is rotated tully 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
COMI in case power is interrupted or the unit is turned off.
Lighting
LED button annunciator and marker beacon lamp intensity are controlled automatically by a
built-in photocell on the front panel. Nomenclature backlighting is controlled by the aircrafr dim-
mer buss.
Transceivers
Audio level is controlled by the selected C0M radio volume controls.
Selection of either COMI, COM2, or COM3 for both MIC and audio source is accomplished by
pressing either COMI MIC, COM2 MlC, or COM3 MIC (la). The acrive COM audio is always
heard on the headphones.
Additionally, each audio source can be selected independently by pressing COMI, COM2, or
COM3 (13). When selected this way, they remain active as audio sources regardless of which trans-
ceiver has been selected for microphone use.
When a microphone is keyed, the active transceiver's MIC button LED blinks approximately
once per second to indicate that the radio is transmitting.
Split COM
Pressing the COM I/2 button (15) activates the split COM function. When this mode is active,
COMI is dedicated solely to the pilot for MlOaudio while COM2 is dedicated to the copilot for
Ml0audio. The pilot and copilot can simultaneously transmit in this mode over separate radios.
Both pilots can still listen to COM3, NAVì, NAV2, DME, ADE and MKR as selected. The split COM
mode is cancelled by pressing the COM l/2 bunon a second rime.
When in the split COM mode the copilot may make PA announcements while the pilot contin-
ues using COMI independently. When the PA button is pressed after the split com mode is acri-
vated, the copilot's mic is output over the cabin speaker when keyed. A second press of the PA but-
ton retums the copilot to normal split COM operation.
@@
NAV 2
=: SPKR =:PILOT
AUOIO tsoLATtot{
:CREW
L-amps
Receiver Audio Select/Mute Button
Receiver Sensitivity Indicator LED.
Receiver Sensitivity Selection Button
/Þ
o
v9.
I.
MKR 2
BCN 3
4.
5. Unit On/Olf, Pilot Intercom System (lCS) Volume
6. Pilot ICS Voice Activated (VOX) Inte¡com Squelch
7. Copilot and Passenger ICS Volume Control (Pull
Volume)
8. Copilot/Passenger VOX Inte¡com Squelch Level
9. Crew Isolation Intercom Mode Button
I0. Pilot Isolation Intercom Mode Button
Level
out for
rcs
I
r3.
COM/ 14.
NAV 15.
16.
s-lHt
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lf the CnM radios utilize a "transmit interlock" systen, the split C1M function
may require that this feature is enabled. Befer to the radio installation manual
for guidance. GABMIN nakes no expressed or implied guarantees regarding
the suiability of the split C0M feature in a given installatíon.
COM Swap Function
The GMA 340 allows the use o[ a remote mounted switch (typically on the yoke) to alternately
transfer the active microphone back and forth between COMI and COM2. Pressing the remote
swirch will have no effect ifCO\,13 is the active transceiver. Ask your installing agency for details.
Aircraft Radios ôr Navigation
Audio level is controlled by the selected NAV radio volume controL
Pressing NAVI, NAV2, DME, ADF (16), or MKR (2) (see MKR Beacon Receiver) selects each
audio source. A second button press deselects the audio. ln addition, the GMA 340 provides inputs
for an unswitched aircraft radio (TEL RINGER) and an un-muted, unswitched aircraft radio (ALT
WRN).
Speaker Output
Pressing the SPKR button ( I 2) selects the aircraft radios over the cabin speaker. The speak-
er output is muted when a COM microphone is keyed. The GlvfA 340 speaker output level can
be adjusted by your installing agency.
PA Function
The PA mode is activated by presing the PA button (ll). Then, when either the pilot's or
copilot's microphone is keyed, the corresponding mic audio is heard over the cabin speaker. If the
SPKR button is also active, then any selected speaker audio is muted while the microphone is keyed.
The SPKR button does no¿ have to be previously active in order to use the PA function. Pilot and
copilot PA microphone speaker levels are adjustable by your installing agency.
Auxiliarv Entertainment Inputs
The GMA 340 provides two stereo entertainment inputs: MUSICI and MUSIC2. MUSICI is
soft-muted during all aircraft radio activity and normally during ICS activity MUSIC2 is a non-
mured input. These inputs are compatible with popular portable entenainment devices such as cas-
seue tape or CD players. The headphone outputs of these devices are used and plugged into
MUSICT or MUSIC2. Two 3.5 mm stereo phone jacks should be installed in a convenient location
for this purpose. MUSICI and MUSIC2 have characteristics that are affected by the active intercom
mode. Refer to the table on page 5.
Intercom Svstem (ICS)
Intercom volume and squelch (VOX) are adjusted using the following front panel knobs:
. LEFT SMALL KNOB-Unit ON/OFF power control and Pilot ICS volume. Full CCW detent
position is OFF
. LEFT tltRGE KNOB-Pilot ICS mic VOX squelch level. CW ¡otation increases the amount
of mic audio (VOX level) required to break squelch. Full CCW is the "HOT MlC" position
(no squelch).
. RIGHT SMALL KNOB-IN position: Copilot ICS volume. OUT position: Passenger ICS
volume.
. RIGHT LIIRGE KNOB-Copilot and pasenger mic VOX squelch level. CW rotation
increases the amount of mic audio (VOX level) required to break squelch. Full CCW is the
"HOT MIC" position.
Each of rhe six microphone inputs have dedicated VOX circuits to ensure that only the active
microphone(s) iVare heard when squelch is broken. This represens a vast improvement over the
panyline systems and reduces the amount of background noise in the headphones during cockpit
communications. After the operator has stopped talking, the inte¡com channel remains momentar-
ily open to avoid closure between words or normal pauses.
The GMA 340 provides three intercom modæ: PILOI CREW and ALL. Mode selection is
accompìished using the PILOT and/or CREW buttons. Presing a mode button activates the cone-
sponding ICS mode. Pressing again deactivates the mode. The ALL mode is active when neither
PILOT nor CREW LEDs are lit. To switch from PILOT to CREW mode, press the CREW button;
from CREW to PILOI press the PILOT button. An LED ON indicates the isolation mode is active.
il
I
T

. PILOT mode isolates the pilot from everyone eìse and dedicates the aircraft radios
to the pilot exclusively. The copilot and passengers share communication between
themselves but cannot communicate with the pilot or hear the aircraft radios.
. CREW mode places the pilot and copilot on a common ICS communication chan-
nel with the aircraft radios. The passengers are on their own intercom channel and
can communicate with each other, but cannot communicate with the crew or hear
the aircraft radios.
. ALL mode allows full intercom communication between everyone plugged in to
the GMA 340. Aircraft radios are also heard by all.
. MUSICI and MUSIC2 srereo entertainment inputs are affected by the intercom
mode selecteil.
The following table summarizes the ICS operation for the diflerent modes supported by the
GMA 340.
MODE PILOT HEARS COPILOT HEARS PASSENGER HEARS MUSICI MUTING
TRIGGERED BY
PILOT
(LED
LIT)
Selected Radios
Pilot. Copilot.
Passengers.
MUSICT.
Passengers.
Copilot.
MUSICI-
Copilot or passenger
intercom activity.
CREW
(LED
LIT)
Selected Radios.
Pilot. Copilot.
MUSICt.
Selected Radios.
Copilot. Pilot.
MUSICI.
Passengers.
MUSìC2. Aircraft radio activity. MKR activity.
Pilot or copilot activity.
ALL
(LEDs
OFF)
Selected Radios.
Pilot.
Copilot.
Passengers.
MUSICI.
Selected Radios.
Pilot.
Copilot.
Passengers.
MUSICt.
Selected Radios.
Pilot.
Copilot.
Passengers.
MUSICl.
Aircraft radio activity.
MKR âctivit)¿
lntercom activity.
MUSICI is normally muted during ICS activity However an instailation option is available to
disable ICS MUTE. Then muting of MUSICI will not occur due to ICS activity. A panel mounted
switch may be installed for this function. The MUSICI mute trip level is adjustable by the installa-
tion agency.
ùlarker Beacon Receiver
The marker beacon is used as part of an ILS approach and in certain instances, to
identiiy an airway. In addition to the normal marker beacon functions, the GMA 340
provides an audio muting function. The lamps illuminate, and an associated keyed-
rone is heard (when MKR audio is selected), when the aircraft passes over a 75 MHz
marker beacon transmitter.
The lamp and audio keying for ILS approach operation are summarized below
Audio
Freouencv Audio Keying Lanp Actuated
+00 -IIIITII Blue (Outer)
1300 ororororo Amber (Middle)
3000 oooooooa White (Airway/lnner)
The ma¡ker beacon audio level is aligned at the factory to produce its rated audio output.
Horvever, rhe audio output level is adjustable by your installing agency.
The GMA 340's marker beacon receiver controls are located on the left side of the front panel
(i-a). The SENS buuon selects either high or low sensitivity as indicated by the HI or LO LED being
iii. Los'sensitivity is used on ILS approaches while high sensidvity allows operation over airway
;narkers or to get an earlier indication of nearing the outer marker during an approach.
The marker audio is initially selected by pressing the MKRi/mute button (2). If no marker bea-
con signal is received, then a second button press will deselect the marker audio. This operation is
simila¡ to selecting any other audio source on the GMA 340. Howeve¡ if the second button press
occurs rvhile a marker beacon signal is received, then the marker audio is muted but no¡ deselect-
ed. The button's LED will remain lit to indicate that the source is still seìected. When the current
marker signal is no longer received, the audio is automatically un-muted. While in the muted state,
pressing the MKR/mute buuon deselects the marker audio. The button's LED will extinguish to indi
cate that the marker audio is no longer selected.
The marker beacon lamps operate independently of any audio selection and cannot be tumed
off. The GMA 340 can drive extemal marker lamps if required.