I have a Salem unit too. I have no idea what brand of radio in in my unit but have only used it twice so I can't say if it is affected by the fan like yours. However, the exhaust fan does interfere with the TV picture but once the fan is turned off the picture returns.
Great choice for "Living within my means" and camping for one...
2011 Salem Cruise Lite 20RBXL & 2011 Toyota Tundra Dbl Cab
Camping History: 45 Trips / 133 Nights / 3736 Miles
FRF Social Group: Campers of the West