My RV-6a originally had only one com radio. When it started to fail in the middle of the SF Class B, it was decided to put in a second. I had a good stero intercom and no audio panel, so I designed and built on a breadboard, an avionics mixer. It had two switches, a "Select", which switches which radio in use, and a "Both" switch which put both radio outputs to the intercom. Also had another input that allowed a alarm input. It had a amplifier built in to mix the inputs and a fail safe feature that put Com 1 directly to the intercom if the thing failed. A 15 pin plug allows it to be removed from the A.C. I buiilt and "potted" two, one for use and the other carried as a spare but never used.
Since it has been flying successfully for about 10 years, I decided to do the same for the -10. Now you can design a P.C board on your computer and have them built for about $25 each for 3 or $15 for 10.
Spent the day designing the board. Will need to spend some more time checking it out and verifying the components, but it looks good now. A lot more fun than fiberglass tips.
