Strange radio noise

I have had a similar problem in professional audio equipment using balanced DIN cables with XLR connectors for microphones.  If one end of the cable is wired properly (+, -, shield) and on the other end, the shield is on the wrong pin (swapped with either + or -) OR the shield is on the correct pin but also shorting to a signal pin, usually through a stray conductor strand, the cable becomes a pretty good AM radio antennea at a very low level.  It usually self-tunes to about 1440 Khz.  A radio station comes through sounding off-channel, as you describe, and at a low level that the amplification equipment makes audible during quiet passages.  I have had this effect ruin the audio track on video tapes and cause long delays in live sound setups.

If this sounds similar to what you are hearing, you might check to see if any of your RCA or antennea cable shield connections are shorted to chassis ground or to + signal.  This is a long shot, but your symptoms suddenly sounded familiar!