Ok guys,

I have an electrical question regarding a Garmin SL30 and a SoftComm ATC-2P Intercom.

Things aren't quite happy working together so I spent the day verifying connections and making sure each wire goes where it is supposed to.

The problem comes when I key my mic button to communicate, all I get is a heavy feedback/staticy garbled sound.

Now my headphones work somewhat correct with the 2 components. My problem with the headphones is it appears that the Pilot only switch position vs the pilot and Co pilot switch position appear to be working backwards. I reviewed the wires and they are per the drawings from Soft Comm. ( I will be calling them tomorrow!)

Soft Comm Intercom

So during my review of the schematics, for the Panel mount intercom for the mic problem, there is a Power ground and a Radio Ground. What are the differences between these 2. Is the Radio ground different from the power ground? Do both go to the airframe or does the audio ground remain isolated from the Power/frame ground?

During the review of the SL30 pin descriptions, there is an audio ground, a Mic ground and a power ground. Same question! Are these to be isolated from each other?

There  is also an audio ground for the SL30. Is this or can this be ran as the same wire as the mic ground? IT seems the Softcomm intercom merges these 2. These all seem to merge at the outer sleeves for the connectors both Mic plug and Headphone plug.

For the SL 30, there is a TX Key "connection" with a described function of; "Transmit enable key, pulled low to transmit". IS THIS for the PTT button on my stick?

I hope this makes sense. I can follow electrical road maps usually without a problem. In this case, the different terminologies confuse me.

Thanks for any help!

Rich Simmons

Views: 265

Reply to This

Replies to This Discussion

I'm not sure about your problem but if you could post some pics of your schematic I'd like to help if I can. My wild guess is the wrong kind of ground at your headset jacks, just a wild guess.
My email is4rcsimmons@comcast.net

Send me a link and I'll forward the schematics.



New from Zenith:

Zenith Planes For Sale 

Classified listing for buying or selling your Zenith building or flying related stuff...


Weather Maps

Custom Instrument Panels
for your Zenith

Custom instrument panels are now available directly from Zenith Aircraft Company exclusively for Zenith builders and owners. Pre-cut panel, power distribution panel, Approach Fast Stack harnesses, Dynon and Garmin avionics, and more.

Custom Upholstery Kits for your Zenith Aircraft:

Zenith Vinyl Upholstery Kits

Zenith Apparel from EAA:

Zenair Floats

Flying On Your Own Wings:
A Complete Guide to Understanding Light Airplane Design, by Chris Heintz

Builder & Pilot Supplies:

How to videos from HomebuiltHELP.com

Developed specifically for Zenith builders (by a builder) these videos on DVD are a great help in building your own kit plane by providing practical hands-on construction information. Visit HomebuiltHelp.com for the latest DVD titles.

Aircraft Insurance:


West Coast USA:

Pro Builder Assistance:


Transition training:

Golden Eagle Aviation

Pianosa Flying Farm

Aircraft Spruce & Specialty for all your building and pilot supplies!

© 2020   Created by Zenith.Aero.   Powered by

Badges  |  Report an Issue  |  Terms of Service