In the 1930s or thereabouts, Crosley's WLW in Cincinnati had a 500-kilowatt transmitter. It was so powerful it was lighting lamp bulbs that weren't even in sockets! Local farmers living near WLW's towers were complaining that they could not turn the lights off in their barns while the station was on the air. The FCC finally put a stop to this nonsense a few years later (I don't know exactly when; perhaps late thirties) when it capped the maximum power output for US radio stations at 50kW.
However, even today, some people living in the shadows of powerful AM and FM broadcasting stations often have real problems with the stations coming in through their telephones, televisions, even the burner coils on electric stoves. Back in the early '70s I lived just one street over from a 27.5-kW (ERP) FM radio station that came in beautifully on my FM radios (on its fundamental frequency of 92.3 MHz and between the other local stations from Cleveland), on my television set on channel 6 (the signal was so strong it didn't care that this channel's frequency range was 82-88 MHz; it blasted through anyway), and even on my dad's solid-state Ampex "Micro 88" stereo cassette tape recorder. I'll never forget one night when we were trying to record a live musical performance at our church; the tape recorder kept picking up the local FM station, and, needless to say, it all but wrecked the recording.
I had relatives who lived in a small rural town between Cleveland and Akron, Ohio (the latter being a small city some 30 miles or so south of Cleveland). There was a Cleveland radio station, 50kW, just about five miles down the road from where they lived; I remember my relatives having the devil of a time with the radio station coming in, of all places, over their telephone! The signal was strong enough that it could be heard as well at two points on the tuning dials of most radios (even the better makes with RF stages ahead of the antenna, etc.) in the area; my grandmother, who had a summer cottage there, had a small General Electric four-tube TRF clock radio that would receive that radio station at two places on the dial (fundamental frequency of 1220 kHz, and about 0.6 MHz down the dial as well, IIRC). I'm really not surprised at that, however, as TRF radios were not known for good selectivity. These radios were made for suburban and weaker signal areas where there were no extremely strong signals to cause cross-modulation and other problems. The GE set my grandmother had, as I said, was a four-tube TRF set and probably sold cheaply (with performance to match) when it was new in the late 1940s.
I don't know what ever became of that little set. My grandmother passed away in 1985, her cottage was sold, and the gentleman who bought the property promptly cleaned the place out top to bottom--including that GE TRF radio and a prewar Silvertone "curtain burner" receiver in the front room of the cottage. Had I been there before the place was sold, I probably would have tried to grab those radios before the new owner so ungraciously pitched them into the trash; however, I lived some 40 miles away at the time and didn't know the radios had been disposed of until it was far too late.
