Debbie, is this an older, 600-700MHz unit? I had this happen with a Senny wireless handheld recently; I'll have to check the model number next time I'm doing work at that particular church. There was a terrible intermittent noise, when the mic transmitter was on or off! I finally realized that it happened every time a nearby TV was turned on. I checked the frequency later, and sure enough, it was one of the older models within the digital TV band. Needless to say, I put it out of commission.
Wireless Workbench is free software, and it will not only tell you what digital TV stations could cause interference at your location, it will pick frequencies for your mics, IEM systems, and RF comm that will avoid those TV channels, and not cause strong intermod products between your systems. It is important that you run this software for the location of every venue you will be at, and update the TV channel database occasionally to keep it current.
Not using this, or similar software is equivalent to burying your head in the sand and hoping no one notices you.
Mac
