Originally Posted by grotto2

I'm going to take a guess that this is an older radio that's more susceptible to interference from outside sources than your other radios. It could be that it has an old wide-band receiver, or is just plain out of tune.
Replace it and save yourself a lot of trouble. Tower will sell you a new Futaba two channel if you can afford fifty bucks. I'm sure you can find similar deals with some shopping.