ORIGINAL: Bob Pastorello
I sure share your concern about preventing RFI. Any suggestions on any measuring I could do to find out if I **am** generating more RFI with my single-battery system? That would probably be good data to collect....
Use an O'scope to look at you battery voltage going into the RX.
With the ingition battery it isn't so much rf noise. The ignition does NOT draw a steady current, but it takes a big gulp of battery just after if fires to recharge the HV capicator. So you are giving your RX a pulsed DC equal to engine RPM, with a shared battery instead, of a smooth DC.
Checking this on an FM RX will give you an idea of the scope of the problem. PCM does better and 2.4 much better BUT the problem is still there just masked. Sooner or later in a higher than normal noise enviroment and when you are low and away BANG your plane is dead.