[Sonnyboy]

I have 3 old vintage radios, and am having a similar problem with all 3. The 2 with AM radio bands will get a strong station signal and I will be listening to the station, and then suddenly the radio will just lose the station. And, when I try to adjust the dial and get it back, no luck. Also, the one slightly newer radio that has a FM band has the same problem. When I turn it on I can hear 1 station kind of in the background with a lot of other stations (noise) in the background as well. When I adjust the dial I can still hear all these other stations until I get 1 strong station. Then after I listen for a while, the strong station will fade out and I am back to noise. I have tried multiple different antennae on all 3 units with no better results.
Is this an antenna problem, or could it be a tube, the tuning condenser....or what? Help...Thanks, Sonny