Is the "white noise" that you hear constant before you switch to the fireground zone?
Yes

Could have the system converted to digital? If so are your RX channels set for mixed mode?
I have it set in mixed mode

Are you able to receive anything on your fireground zone?
not sure we have not had a ...

My xts 3000 was working fine then it "locked up" and I can't hear any audio all I hear is something like white noise. The buttons and controls all work, but I can not receive any freq that i have programmed as conventional but are on a trunked system. I do not have a system key nor did I. When I ...