Dynon Comm Push-to-Talk?

[Mark P.]

I rolled my plane out of the hangar yesterday and tested the radio and intercom. The intercom works great, and I can hear airplanes making traffic calls at airports 30-40 miles away. Not bad for sitting on the ground next to the hangar!

But it looks like my push-to-talk might not be working. No one answered my radio check, and when I talk with the push-to-talk button pressed I can not hear myself in the headset. For example, if I'm talking over the intercom and I continue talking while I press the button, it cuts off my audio so I can't hear myself talk. Usually on radios when one presses the press-to-talk button his voice still goes through the headset so I can hear what I'm saying.

The push-to-talk switch is probably the easiest part of the entire airplane to wire, so I'm confident I have it wired correctly...but any idea what might be happening?

On the DYnon radio, should I be able to hear my voice while transmitting?

Thank you

 

[CGameProgrammer]

If it cuts off your audio when pressed then it is working correctly. When you push the PTT button, the intercom is muted (for the person pushing the PTT) and instead sidetone is used to relay your voice to yourself. So your sidetone setting is likely too low.

Go to Setup -> Com Setup and first do the microphone gain test to ensure it reads "GOOD" when pushing PTT and saying "testtesttest". (Obviously use an inactive radio frequency.) Then you can set the sidetone level.

 

[dynonsupport]

First things first. The COM radio screen should say TX in the corner when you are transmitting. Is it doing that? If not, something between the intercom and the radio is wrong.

 

[Mark P.]

When I press the push to talk button, the "Power/TX" light on the intercom goes from green to orange, but TX does not appear on the radio screen.

Also, if I key the mike while someone else (like another plane) is talking on the radio, it does not cut them out so apparently I am not transmitting.

I better check all the wires from the intercom to the radio as I'm guessing that's where the issue is?

 

[Mark P.]

OK I found the issue, but now have to figure out how to 'fix' it.

I took my D Sub connector apart that connects to the COM-425 and I never installed the wire going from pin 5 to pin 12 on the SV-INTERCOM-2S.

I think once I install this wire it will work, however, my intercom has a premade harness coming out of it and I have no idea where to find which wire is connected to pin 12!

Dynon-when you make these harnesses, there are a bunch of shielded cables coming out of the D Sub. In one of those must be the wire from pin 12. Which white shielded cable does that wire live in?

 

[Mark P.]

I wanted to follow up in case I can help anyone else out.

I'm guessing that almost everyone uses the pre-made intercom harness from Dynon. There is a shielded cable with three wires which is labeled "Radio Mic Out".

The issue I was having in the original post was because I had none of these wires connected. DUH!

In this cable (since Dynon does not provide this info for some reason) the RED wire is pin 25, the YELLOW wire is pin 12, and the BLUE wire is pin 1 (ground)

So now I know that intercom pin 25 goes to SV-425 pin 1, and intercom pin 12 goes to SV-COM pin 5.

My final question is, where does the blue wire (ground) connect to?

Does it connect to a ground in the SV-COM 425 DSub connector? Does it connect to aircraft ground?

EDIT: I got it...PIN 2!!!

 

[mrdaud]

BAC - Dynon suggests no audio related grounds be connected to AC ground buss. All the Comm ground wires should be interconnected in parallel (including Comm pin 2) to the Audio/Power ground pin 1 on the Intercom. You can see this clearly in the Dynon install manual on page 16-11.

 

[jakej]

That's standard audio practice - also the shields are grounded at the intercom, or audio panel (whichever is used) but never at the Comm end.

 

[Raymo]

In this cable (since Dynon does not provide this info for some reason) the RED wire is pin 25, the YELLOW wire is pin 12, and the BLUE wire is pin 1 (ground)

This information IS documented in the installation manual. I did not purchase this harness from Dynon. It is easy enough to make.

 

[Dynon]

And just an FYI, for those of you that have purchased our pre-made intercom harness - we now have a pinout guide for it: http://www.dynonavionics.com/product-accessories-documentation.php (intercom tab)