My Zenith TransOceanic 12-band radio, from 1966, works very well (and sounds great; no rattling or other noises, as have been reported by some other owners of these sets). However, I noticed recently that, with the radio in my bedroom, the local AM station in the next town (about two miles or so distant) is extremely distorted, as if the radio's batteries were weak or nearly dead. (The batteries are good.) However, other stations come in clearly with no distortion at all. When I take the radio into the front part of my apartment (the main living area), the local AM station comes in as clearly as it should. Moreover, I can hear many other AM stations with the radio in this location than I can with the set on my dresser in the bedroom.
Why would a small change in location make such a large difference in reception, and clear up the distortion on the local station?
The station is 1kw daytime, 500 watts at night. There is no distortion on FM or shortwave, just AM. If the distortion on the local station (which, needless to say, is putting in a very strong signal at my place, even for a 1kW station) were also apparent on all other stations received on the AM band and shortwave, I would suspect a problem with the AVC circuitry, but again, since there is no distortion on any other AM station or any of the radio's other eleven bands, that circuit isn't causing the problem. What else could be causing this? I don't listen to the local station that much, but I wonder about the difference in reception quality between the two locations in my apartment. Could the radio be picking up a much stronger signal in my bedroom, thus overloading the AM front end?
This radio has an AM/SW RF amplifier stage, which may well account for the distortion on the strong local station. The signal is very strong as it is, but when it goes through that RF amplifier transistor, I'm thinking it would now be so strong as to overload the AM front end to death.
That would not, however, account for why the local station clears up and is perfectly listenable elsewhere in my apartment, and why I can receive most of the AM stations in Cleveland clearly when in the main living area. The only explanation for this I can come up with is the manner in which the apartment is situated within the building. I am on the first floor, and my bedroom is just off the kitchen area. Could it be that the bedroom is actually closer to the radio station's towers than is the rest of the apartment, thereby presenting my T/O with a signal so strong it just overloads the radio?
Thanks for any insight you can provide on this. I'm baffled as to why this is happening, but I guess I should be thankful the local station is only 1kW/500 watts (daytime/nighttime power, respectively) and not 50kW full time! Needless to say, the signal from a 50kW station at just two miles would swamp every radio I own (not just my T/O), and I'd probably be hearing it on the burner coils on my electric stove and even my bedsprings, not to mention my stereo system and/or the sound system in my television, when the sets are turned off.
I now have at least a small (very small) idea of what folks living near the original 500kW transmitter of station WLW in Cincinnati, Ohio in the 1930s were having to deal with--lights they couldn't shut off until the station signed off for the night (there were reports of folks who couldn't turn off fluorescent bulbs and had to put them in closets), arcing, etc. My problem is nowhere near that severe (the nearest 50kW station to here is 35 miles distant), but I'm still wondering about the distortion issue and why my AM reception improves in different parts of my apartment. The only things I can figure that could cause the improved AM reception, again, are the way the apartment is situated within the building, or even the direction in which the entire building faces.