Hi aBug,
sorry for the late response, after a lot of testing I could mitigate the vibrations effects lowering I and D values, but the effect was definitively there, with more weight it was more noticeable and slight changes of CoG also affects the issue. I'm giving up with this frame/FC combination, it's not worth it the soft orange bobbins are a problem for Autoquad. This was my first build when I started FPVing, it was collecting dust... I tried to recycle it, but it seems like a bad combo. With other FCs the frame works very well, I wonder what is the difference here.
This is the GNSS antenna I'm using
http://www.tallysman.com/wp-content/upl ... _Rev21.pdfI had two from another project hanging around, it should be better to use a GLONASS compatible one with wider bw +1600Mhz. Since I'm not receiving any other signals than GLONASS ( the lower bands ) and GPS. I'm using a 100mm diameter round pcb as a ground plane, cutted with scissors. I removed the magnet and soldered the can shielding of the antenna to the PCB ground plane.
I just followed the minimum required ground plane size for not detune antenna too much, the manufacturer of this antenna recommends 1/2 wavelenght.
I never tested MAXTENA helical GPS/GLONASS antennas, but they don't require ground plane like patch antennas, it's interesting area to dig about.