newt
Well Known Member
Yes, I'm aware that the GMA340 has been EOL'ed by Garmin.
I have a GTR 20 remote-mount VHF cabled into COM1 on a GMA340 audio panel.
The GMA 340 has a COM1 pass-through, where an internal relay connects the command pilot's headset, mic and PTT to COM1 when power is removed.
I've designed my panel to make use of this feature, with one switch which lights up the GTR 20 and the G3X Touch PFD so I can listen to ATIS or talk to clearance delivery with minimal power draw before engine start.
This mode of operation works perfectly when I plug in the cheapest nastiest oldest most falling-apart headset I own.
When I plug in any other headset (a David Clark, a Clarity Aloft, and the headset built in to my Bonehead Composites flight helmet), I get very low receive levels. Low enough that I can't hear the radio at all if another airplane is taxiing past.
It seems there's a subtle wiring fault, or maybe an impedance mismatch of some kind (??), but I can't think of one that'd cause these results.
(It's not the stereo/mono selection on the headset. The GMA340 manual notes that it's not supposed to work at all if that's wrong)
Any ideas?
- mark
I have a GTR 20 remote-mount VHF cabled into COM1 on a GMA340 audio panel.
The GMA 340 has a COM1 pass-through, where an internal relay connects the command pilot's headset, mic and PTT to COM1 when power is removed.
I've designed my panel to make use of this feature, with one switch which lights up the GTR 20 and the G3X Touch PFD so I can listen to ATIS or talk to clearance delivery with minimal power draw before engine start.
This mode of operation works perfectly when I plug in the cheapest nastiest oldest most falling-apart headset I own.
When I plug in any other headset (a David Clark, a Clarity Aloft, and the headset built in to my Bonehead Composites flight helmet), I get very low receive levels. Low enough that I can't hear the radio at all if another airplane is taxiing past.
It seems there's a subtle wiring fault, or maybe an impedance mismatch of some kind (??), but I can't think of one that'd cause these results.
(It's not the stereo/mono selection on the headset. The GMA340 manual notes that it's not supposed to work at all if that's wrong)
Any ideas?
- mark