Do you sometimes have transmit issues with your NARCO
MK-12D through your Garmin 340 Audio Panel? I really like these radios, they've
performed well and are now easily found in decent shape on EBay, so I was
reluctant to give up on them when these issues crept up.
No side tone sometimes and when you turn the
audio panel off (failsafe mode of audio panel is direct connect of Com1 to
transmit) but your transmissions are OK but chopped off?
Well, this is the verbatim fix
given to me by the NARCO techs that solved my problem:
"There is no bulletin
concerning the Garmin 340 audio panel. The work around is a simple fix for your
avionics shop to install. All they need to add is a 1K ohm 1/4W resistor from
the MIC AUDIO line (PIN N of J101) to GROUND on each of your MK12D trays."