Both radios in my A36 (E632), are experiencing what sounds like ignition noise that varies with RPM. I hear the noise in the #1 radio, a Garmin 530, only when I receive a transmission. However, I hear the popping noise anytime the #2 KX155 is turned on. My mechanic grounded some of the ignition wires & cleared up about half of the noise. Any thoughts on a diagnosis? Thanks & I hope to see you in Oshkosh.