A band I played in that had an older Peavey PA amp and mixing board would pick up business band radio. This was bad at the local civic center auditorium, next to a major interstection. A transmission would come through and apparently cause a high frequency oscillation (in the RF range?) which would smoke the piezo tweeters in the PA speakers. It was amazing to see smoke coming out of those piezo horns.. hahaha! Never did get that system to stop that. Going to newer equipment solved the problem eventually.