Biggest issue was bad COM recepttion...really unreadable after TO. Able to return to airport...hardly could hear approach. .6 on hobbs. Tower not better until I got 3 miles out. Loud, broken squelch on both radios. Trouble shot over 2 days. Jason thought it might have been COM and NAV cables crossed. First, manually traced all COM and NAV antenna cables. No small feat working behind panel... did remove 1 GDU finally (didn't want to open the pitot-static system). All looked good. Next day actually metered out everything. Found COM1 cable that goes to antenna in VS had tone on signal pin AND ground! Worked everything back and determined that that short to ground was on the COM1 emergency bypass switch. Swapped connections to box and still had that VS cable grounded. Used a coupler to bypass the bypass box entirely... meters out good. Some home grown looking part from Aerotronics. Did not have time to ops check outside. Other squawks...FF reads about 2X high; check setting at ~67000 and replaced fuel cube; Heat seemed to be ON... need to review valve ops. Prop not making full RPM (2530 vs 2700) ...will check governor stop. Also set both COMs squelch back to factory defaults. Need to get MP on PFD screen. Adjusted fuel PSI alarm set points
