Hi All, Here's my latest. I swapped out the 170 that appeared to be the culprit. Reasoning; when I unplugged that module noise went away. Wrong, made absolutly no difference. So, I strip 66 block associated with that 170, and station by station,I reconnect and listen. Got down to the last three stations and noise came back. So my reasoning is it's one of the three. Through process of elimination, I get it down to one station. No noise for a couple of days; then BAM, it's back. The volume of calls seems to have a direct effect on volume of the noise. The crazy part of this thing is the noise is moving around to different stations at diffetent times. Again; thanks for your suggestions.