I have an RFI problem in my apartment as well, only I don't think I'll be able to do much about it. The problem is harmonics of 15,750 Hz, the horizontal oscillator frequency in TVs. They appear at random spots on the AM radio dial and almost always seem to show up right on top of weak music stations I'd like to listen to; there are several such stations within 50-80 miles of here that are completely unlistenable due to the interference. Unlike wa2ise's laptop charger which he can shut off, however, I think I am more or less stuck with my interference problem, as there are several tenants in my building who apparently like watching soap operas or those crazy talk shows on TV in the afternoons.
The interesting (and baffling) thing about my interference problem is that it doesn't seem to show up much, or at all, after dark. That's TV prime time; I'd think I would have even more of an RFI problem on the AM radio dial then than I would in the daytime. I think, however, that the reason I don't have nearly the problem with horizontal oscillator birdies on my AM radios at night is there are more 50kW stations coming in after dark, and even smaller stations may be running more power (in the thousands of watts) at night than they run during daylight hours. I don't know of any stations in or near my area that do this (most smaller stations in the Great Lakes region that do not operate at 50kW actually run less power with directional signal patterns or sign off after dark), but I have seen listings (in RadioStationWorld.com) for stations in the southwestern US, particularly in border states such as California, Arizona, Texas, etc. that in fact do increase, rather than decrease, their power output after sunset local time. I think they do this to combat interference from stations in Mexico. I'm amazed that stations in my area (which is only a mile or so from the south shore of Lake Erie) or those in northeastern US states like Vermont, Maine, Massachusetts, etc. do not do this, as they are not that far from Canada. I'm only perhaps 150 miles from Detroit, which is a hop skip and a jump across the lake from Windsor, Ontario. The latter has AM 800 (CKLW), which runs 50kW 24/7 (no nighttime power decrease or signal pattern changes that I know of) and has for decades; no interference problems. The same goes for the 50kW stations in Detroit, which are heard in southwestern Ontario as well. This is amazing, to me, especially on 800 kHz, since the US stations on that frequency used to have to sign off at sunset local time to protect CKLW from interference. In those days, before the FCC did away with clear channels, CKLW was the only station on 800 kHz at night in North America, and at most only two stations could operate after dark on the clear channels in the US. In my area, the dominant station was WKYC 1100 (now WTAM) and, on the West Coast, KFAX 1100 in Los Angeles. The other stations, mostly daytimers, had to sign off at sundown local time. The other 50kW station in my area, WGAR 1220 (now WHKW) was not a clear channel operation. It had to, then as now, decrease its power and change its signal pattern at night to protect a station in southwestern Ontario on the same frequency. A 50kW sportstalk station on 850kHz in Cleveland must decrease power to 4.7kW (4700 watts) with a different pattern at night for roughly the same reasons, the only difference being that the stations being protected from skywave interference are in Denver and Boston. Both these stations are 50kW as well, but if the Cleveland station ran its 50kW signal (same antenna pattern) all night it would clobber the other two, but good -- even, I think, during so-so propagation conditions. About 25 years ago, I heard KOA 850 in Denver early one Monday morning (about 1 a.m. or so, IIRC), after Cleveland's station on that frequency (WRMR, IIRC) had signed off for technical maintenance -- the first time I had ever heard any AM radio stations west of the Rockies from northeastern Ohio. I haven't heard anything from Colorado, or anywhere else further west than Texas, on AM since. Probably due to that 15750 Hz TV horizontal oscillator interference I mentioned above.
