"It's unlikely it vibrated loose. It was between some rubber bands and some foam. The foam was glued to the plane.

Yes, single cylinder motor. Do you have any experience with vibration issues? If vibrations were an issue, I would expect maybe some…"

"I had some 1/2 inch foam under the APM for dampening vibrations. "

"Throttle up, then throw into the wind. APM will at least keep the wings level so you can concentrate on a bit of elevator to gain altitude, though FBWA will keep the pitch level if the plane has enough airspeed.

I don't have a finwing penguin, but…"

"I take off and land in FBWA mode all the time. The autopilot does a much better job than me when it comes to reaction times."

"Thanks for that. I decreased from 30 to 28Db. Jitter decreased substantially. Will try adding caps now."

"Brian that's interesting. I will give that a go. Maybe time to pull out my oscilloscope. It's 100mhz so it won't see any 915mhz noise but it might give me a clue as to the PWM shape change with/without the capacitor."

"My pixhawk is in the mail. So far I have only tried APM"

"I have moved it as much as I can. The jitter never goes away completely unless I disconnect from APM. I would wager that an optocoupler on the tx and rx lines would fix it. Yes the cable from APM to rfd is shielded."