Solution to TruTrak PTT pitch up

There is a long thread in another post that is pretty old with no real solution to this problem of the TruTrak autopilot pitching up with the push to talk button. It is an isolated problem but, if it affects your installation it is a real bear to isolate the source. After many attempted fixes that did not work this one did.

I followed the link as previously posted on the filter that goes between the head and the harness made by Digi-Key, purchased it, installed it in 5 mins, and it solved my pitch up problem with my PTT. I believe my problem originated with my using a single shield coax instead of a double shielded coax like RG400 on my radio antenna. I did route my coax completely separate from all other wiring, but apparently the Garmin puts out a lot of RF. Here is the link and the part cost $27 plus shipping. Good luck!

http://parts.digikey.com/1/parts/1599616-filter-male-female-adpt-25pos-fce17-b25ad-250.html

Don
RV7
PHX

Thanks Don

Don,
I ordered mine yesterday!
I hope it works works for me as well.
I had replaced my coax with RG-400 and added extra length, per Lucas's direction. Some help, maybe 50% improvement.
I still needed to pull the control box and send it back for a metal case.
Maybe the filter will keep me from having to do that also.
Thanks for posting the direct link, that made it easy for me to click to order!
Thanks again.

Where is the filter installed?

I searched for the post you mentioned and couldn't find it.

Where is the filter installed? At the control end or the servo end of the harness?

Sweet!

I've been scratching my head over how to solve this but the thought of using an inline DB25 filter never crossed my mind. Ordering mine today too!

Thanks for the report, Don.

Kev

Dave

Hi Dave,

The filter goes between the control head (the ADI in my case) and the harness that goes out to your servos.

Hope that helps.
Don

Fixed Mine Too!

Not to wake an old post... But, found this information invaluable. Ordered yesterday, arrived today from Digikey, and installed no sweat. Solved the weirdest problem I've ever run across... Really... Cruising along on ALT HLD; replied to ATC and climbed 200ft! I was hesitant to even mention it for fear that folks wouldn't believe me. I appreciate the advice.

Mine does it too with Garmin SL-40 Com 2 transmissions only. No problem with 430W Com 1. I will try this fix. Thank you.

A friend of mine had the same problem in his Bearhawk, and wrapped his autopilot in mu metal foil to shield it. A bit pricey, but works.