mm wrote:
I have an clock radio about 30 years old that, when tuning for 88.5
FM, for example, by turning the dial, will find that station, and then
a little higher will be another station, and a little higher still
will be 88.5 again, often a stronger signal than the first one.

I'm sure it's not a second station playing the same stuff.

I know about harmonics on AM MW and Short Wave, but here the tuned
frequencies are so close, and also I didn't think there was stuff like
this involving FM. What is going on?
Intermodulation maybe? Or even something oscillating in the radio inter-
modulating the station?
Or a support transmitter in mountainous country put on some hilltop?
Or a far away second transmitter?
In my country I can find the same station on several frequencies,
because one transmitter cant cover the entire country.