On my TT the roof antenna goes to the signal amplifier like the one shown by Roy B.
The back of the amplifier plate has two inputs, one for my roof antenna that goes through the amplifier, a second input for the outside antenna jack; for use with campground cable. A third connection is the output to the tv.
The push button on the front lights up when the roof antenna and amp are on and switched to the tv, when pushed again, the amp light goes off and the outside antenna jack is then connected to the tv.
I the past I have mix the two inputs. This meant the amp was connected to the outside line with no signal to the tv. when the light was on, or the roof antenna was connected to the tv with no amp when the light was off.
I hope this helps.
