I was searchin' around and found this in the faq at dunlop:
"Getting radio stations on your wah pedal is unfortunately, the nature of the beast, and has been that way since its inception. In some areas it is worse than others. It is especially bad in the great lakes region because the lakes act as large antennas sending out the radio signals to all areas - and all wah pedals."
how true is this, I grew up in milwaukee and never really had much of a problem with pickin' up radio frequencies with a wah or pedal. Most of the hardcore shows were in basements so maybe that helped? but practiced in garages, played in bars, lived on the second floor less than a mile from the lake. Hell I used to have to spend hours trying to pick up wmse (the engineering schools alt. radio station) what's the scoop? are they (dunlop) just blowin' folks off?
-matthias
I don't know about the lakes acting as big antennas, but they were either just blowing people off or were themselves uninformed about the circuit and/or RF interference.
Any circuit can be made to ignore RF. It may take some doing, but getting RF out of a wah is no huge problem. You can shield it out or make the circuit insensitive.