Check Antenna Couplings
I had a bad intermittent static problem with my radio reception and transmissions and discovered during some unrelated work that my connection to my antenna was faulty. Redid the connections and the problem disappeared. Good luck with your hunting.
Jim Harris, 2008 RV7A, 2nd owner, N523RM
Superior XPIO-360, Hartzel CS prop, Older Aerotronics panel with Dual GRT Horizon WS, EIS, Garmin 340, 335 ads-b out, Dual 430s (non-WAAS), TruTrak 385 A/P w/auto level, Electric trim, Tosten 6 button Military Grips, FlightBox wired to WS, Dynon D10A w/battery backup, 406 MHz ELT. Custom Interior, Great POH!
Retired - Living the dream - going broke!