Garmin GMA 347 Pilot’s Guide
190-00325-00 Rev. A
10
Operation
When in PA mode, the
SPKR
LED blinks at a faster rate than
that of the
COM MIC
key indicators.
NOTE: Garmin makes no expressed or implied guar-
antees regarding the suitability of the Split COM
feature in any given installation.
Transmit Interlock
An aircraft installation with transmit-interlock activated op-
erates in the following way. When one or another transmitter
is keyed, all other receivers are cut off so that they won’t pick
up the active COM transmitter interference. This is the pre-
ferred option for single pilot operation.
For aircraft with two pilots aboard, transmit-interlock may
interfere with communications. When the pilot or the copilot
transmit, no audio is heard on any other receiver. This means
that if the pilot is communicating with ATC while the copilot
transmits on another radio, all pilot reception is lost during the
time of copilot transmission.
If the installation does not have transmit-interlock activat-
ed, all the receivers are listening all the time whether any radio
is transmitting or not. Split COM performance varies signifi-
cantly across installations. In small aircraft, interference is af-
fected by both the distance between antennas and the tuned
frequency separation.
If the transceivers interfere with each other, transmission by
one radio produces static or squeal, thus loss of communica-
tion from any other radio.
Split COM can be disabled in the Configuration mode.
Contact a Garmin-authorized service center for Split COM and
transmit-interlock configuration.
COM SWAP
A remote mounted pushbutton switch may be used to
transfer the active microphone between COM1 MIC and
COM2 MIC. Pressing the switch has no effect when COM3 or
Split COM is active.
Contact a Garmin-authorized service center for details on
the remote COM swap option.
190-00325-00_0A.indd 10
6/15/2005 10:09:10 AM
