On Jun 1, 9:35 pm, mikem wrote:
On Jun 1, 5:03 pm, Steve - KDMW wrote:

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.

That sounds like the SL40's intercom function is competing with the
SPA400

I forgot to mention... I also checked to see if the Sl40's pin 12 was
shorted to ground, which would enable the SL40's Intercom function and
it wasn't. But just for the heck of it, I changed the Sl40's intercom
volume from 000 (slaved to the volume knob) to 001 (lowest volume
possible) to see if it would have any effect and it didn't.