Do you have an external radio antenna?
Our RV doesn't so it uses the tv antenna for the radio signals.
If yours doesn't have a dedicated radio antenna try turning the tv power injector (button on wallplate) on and see if that helps.
If it does have a dedicated radio antenna, I'd start looking for loose antenna connections. Starting behind the radio.
Salem 29RKSS Pushing a GMC Sierra 2500HD!
Gotta go campin!