[Neal@F14]

I'm wiring up a Garmin 430 for a friend's RV-8 and there is not going to be a formal audio panel, just a simple intercom.

The 430 has two separate 500 ohm balanced audio outputs for COM and VOR/ILS.

I don't have any spare audio inputs left on the intercom to connect the VOR/ILS audio output of the 430 to an intercom audio input of its own like I would have with a genuine high-end TSO'd audio panel, so... should I just tie the 430's VOR/ILS audio output HI line to the COM audio output HI line going into the intercom's radio input? Maybe thru a resistor to provide a little bit of isolation between the two audio output circuits to keep them from dragging each other down? (1K, 2K, 4.7K, 10K ?) Or perhaps make a simple "passive mixer" circuit and put a resistor in line with each of the two outputs and then blend them together to go into the intercom's radio input?

 

[BushCaddyBuilder]

Any info on this?

I have the same question. Anyone have any input?

 

[vic syracuse]

Audio mixer

Use an audio mixer such as this:


http://www.aircraftspruce.com/catalog/avpages/flightdataAP60audiomixer.php?clickkey=24753

Vic

 

[BobTurner]

Vic's solution is the best one.
If you're handy with a soldering iron you can build your own for $5 (plus connectors), google "mixer circuit".
However with just two inputs a "passive mixer" will work okay. Use two 330 ohm resistors, one in each line, then tie both ends into the one intercom input. You will need to turn up the volume higher than before, but the 430 has plenty to spare. Turn down the nav volume to "switch it off".