I remember my first encounter with the phenomena about a year after getting my Grenade. I had the transmitter sitting on the box I used for packing it and my gel-cells into my tx sites. I got the audio level I wanted and turned off the receiver to save battery life. I was literally in the middle of nowhere, it was dead quiet. Damned if I didn't I start hearing familiar music? I thought it was RF getting into the "off" receiver, so I picked it up to give a listen. That wasn't it, it was coming from the box. The thing was acting like a resonator for the modulation xformer.