On May 30, 11:54 am, "RST Engineering"
wrote:
Agreed. Good place to start.

Jim

"mikem" wrote in message

oups.com...



On May 29, 6:30 am, Steve - KDMW wrote:
This leads me to believe that the headphone COM120 output was NOT
wired to the isolated summing input on the audio switching panel as it
should have been.- Hide quoted text -

- Show quoted text -

OK. Well, I ohmed out the wiring and found nothing unusual. The SL40's
headphone output was wired to the KA-134's Com 2 Audio In (and nowhere
else). I checked to see that it was not paralleled (shorted) to any
other inputs. All of the grounds read properly, i.e. to ground, and
nothing shorted to ground that shouldn't be.

The one thing I have not checked yet is to make sure that the radio
goes only to the audio panel, and not paralleled to the intercom. Only
the audio panel output should go to the intercom. I don't believe
there is a problem there or it would seem that I would always hear the
Com 2 radio regardless of audio panel selection. But I'll check it out
anyway.

Another tidbit of info. The intercom comes back to normal if the
Garmin radio is on and not selected. It doesn't load down the intercom
simply by virtue of being on, it has to be on and selected.

Still waiting for the shop to get back to me with their suggestion.
Maybe the 100 ohm resistor on the radio's headphone output is the way
to go. Also, I'll be going to the AOPA fly-in tomorrow and I'll pick
the brains of the avionics shop's booths and Garmin's reps.