robotique said:
Remember the old all news WEEI 590? As a kid, I seem to recall that whenever you tried to tune this station (analog tuner), it was always accompanied by a buzzing or whistle of varying pitch. It didn't matter if it was a cheapo radio or a high end. Anyone remember this? What was the deal...
If this was happening during the mid-day hours, every day, as well as at night, it was probably more likely a local phenomenon rather than a skip from across the pond, which would be more likely to occur only at night or late in the day.
Were you close to the old WMEX 1510 transmitter, or in an area where its signal was strong? 600 kHz, just 10 kHz above 590, would be 910 kHz below 1510, double the commonly used intermediate frequency of 455 kHz then used for many AM radios. This often caused a weak image of a station to appear 910 kHz below its actual frequency on the AM dial, which could interfere with a station on the same or adjacent frequency on which this image appears, often resulting in a heterodyne tone or whistle that varied with the tuning of the radio.
For example, where I grew up in Newton, a weak image of WNTN (1550) also appeared on some radios at around 640 on the dial, 910 kHz down. There was nothing locally on that part of the dial back in those years, but when I'm in the area nowadays, I notice a heterodyne whistle appearing on top of 650 WSRO Ashland, which I'm guessing must be being caused by the radios IF reaction to WNTN. It also disappears at night, after WNTN signs off.
Also, growing up in Newton, whenever I went near the immediate Oak Hill area, I noticed an IF generated signal from WUNR 1600 AM appearing on 690 AM (again 910 kHz down), causing whistles and interference, etc... to adjacent WRKO on 680.
The directional signal of the old WMEX 1510 was weak where I grew up in Newton, so it was not capable of causing any IF interference to the old WEEI 590 there, but I recall back when 1510 was moved from their old Quincy site to their current Waltham site a few decades ago, many people in the immediate Waltham and nearby Belmont area complained that they could no longer even get 590 WEEI because the IF generated interference (on adjacent 600 kHz) from 50 kW 1510 right in their neighborhood completely buried the 590 signal on their radios. The owners of 1510 at the time had to spend a small fortune on some sort of special radios or filters of some sort for people in the immediate area.
Modern AM digital tuners generally seem to do a better job of filtering out, or not reacting, to these IF generated signals.