@Kaputnik, cool, that makes sense, it may even be a harmonic of the main KFM signal that's interfering with your "proper" wireless station reception.. they probably run stupid power outputs :-/
Let us know if the extended antenna thing helps btw, the main rule with signal reception is the more wire in the sky the better (until the strength of signal overpowers your receivers ability to cope!)
A good design is also very useful, (almost a requirement for transmitting (but not quite!)), but for receive just a simple more is better is a good start with arials :)