Acceptable Ground for A/P Disconnect

[N26EX]

Hi,

On a Skyview System. I'm wiring the pilot's control stick with PTT, A/P disconnect, and Freq flip flop switches. Can I use the PTT ground (SV-Intercom pin 2, Mic Ground) for all three, or do I have to run a separate ground wire from pin 1 to the control stick for the A/P disconnect and Freq flip flop switches?

Thanks 

 

[dynonsupport]

You can use the PTT ground for all of these, or even just any local airframe ground you have near the stick.

 

[Battson]

Yes - you can run the PPT to all three..... or any old ground - but I have had advice that this can induce noise in the radio / intercom. Not for certain, but depending on your model there is are examples.

If I had my time again - I would run two wires, just to be safe, keep everything abouts the COM seperated from the electrically noisy EFIS / trim etc.   Also sheilding everything around the COM is never a bad idea, and running all earths to a starpoint. That way there cannot be any earth loops in the airframe to interfere with the radio.

If Dynon Admin knows otherwise for a fact, then I'll stand to be corrected.

 

[dynonsupport]

The ground is only hooked to the radio while you are actually pressing AP disconnect or flip/flop, so any noise you get would only be during the short button press. Even then, I really don't see an issue since these are not high current wires. No harm in separating them.

 

[Battson]

I tested mine last night and you can *only just* hear when the trim is operating and you PPT at the same time, it's there but it's very small. So maybe not a big deal after all... mine is an all-metal airframe.

 

[coyote]

If the PTT, AP disconnect, and trim are all grounded at the stick, does pin 2 on the SV intercom need to be attached to anything other than the mic jack?  The stick ground and the SV intercom ground (pin 1) both terminate on the same avionics ground plate.

 

[Dynon]

Ideally you want to use the intercom ground only for the intercom lines and mic, grabbing a local ground for the others. But that being said, 95% chance everything will work just fine the way you have it. Worst case, there might be a little more noise in your audio system, but probably not even that.