SL-40 and Flightcom 403

I figure no question is too stupid to ask

I'm wiring SL-40 to Flightcom 403 intercom. SL-40 has two wires I'm not sure about -- "audio lo" and "mic lo" (that's how Stark marked them -- I believe those are grounds). Intercom doesn't have pins for those two, so should I run those back to my ground tabs or leave them unconnected?

The radio is receiving just fine in my garage.. I can hear commercial traffic flying near my house. Haven't tried transmitting yet since I don't have my real antenna installed yet.. this is testing with a handheld's antenna for now.

Thanks!

IIRC ... Ground them

I will go check what I did if you wish.

James

Ground is usualy marked by "GD", or "-".

"lo" is, I suspect for low impedeance inputs. If so, then hooking to ground may cause the smoke to escape.

Escaping smoke is generaly a bad thing.

Check with whoever marked them???

Mike

What pins are they going to?

Mike, I initially thought the same, but I don't see anything on SL-40 pinout to indicate there's a such thing. It shows "mic ground" and "audio ground" so that's why I suspect they're grounds.

James, can you check when you get a chance?

Jamie, no easy way to tell now with the radio in the tray.


Thanks!

Ground them at the intercom....

Looks like they are "returns" for the Mic and audio out signals.

If no separate inputs on your audio panel are available, then they should be connected to a ground as near the audio panel as possible - preferably at the ground (or audio return) pin on the intercom box.

I would presume they go to pins 13 and 7 on the SL 40 connector.

Thanks to "Rosie" the manual is here....

http://www.eaa49.av.org/VAF/sl40_install.pdf

If in doubt, read the instructions....

UPDATE

Treat them as "avionics ground" using the schematic on page 9 of the other end's manual...

http://www.flightcom.net/pdf/403-403dManual.pdf

gil in Tucson

Thanks Gil.. that's it.. got the same response from John Stark...