I wish I'd written down all the places where I was getting FM radio intermod, but a while back I'd noticed a problem in the 30-50 MHz range. I discovered quite by accident that if I had an existing adjustable notch filter set at just above 100 MHz, reception in that range increased markedly. And there was no obvious intermod at that range, just noise. Now, the MSP Waterloo barracks comes in S9, and I can actually hear the Westminster barracks, which I never heard here in the city. I don't know what that is, it just is...
There are places all over the dial between 30Mhz and 1GHz I pick up obvious intermod, most of which was from FM, though some are from TV--you don't live this close to TV Hill and not pick up something you don't want. Of course those spots are going to be different depending on the make/model of the radio (I'm using a Winradio, usually).
Now that I think about it, I've also gotten back a couple of aircraft frequencies that were lost to FM radio, and there were a couple of 2-meter repeater frequencies that I'd had to add to the Exclude From Scanning list back in the day because of FM interference that I can now hear absolutely nothing on, more listening will prove that it was an FM, but listening to 2-meter hams talking their lives away about exactly the same thing ranks right up there with watching paint dry, grass grow, etc., so results might not be forthcoming for quite a while, unless I stumble across a repeater that I never heard anything from before but do now.
I don't do enough HF listening to make an evaluation in that range, unfortunately, but if someone wants to help me make a longwire and shoot it over to the Belvedere's roof with a grappling hook and a rocket, we can try it out. Even with just a discone on the roof I can get most of the USCG weather fax stations east of the Mississippi good enough to decode, and sometimes Point Reyes on a good HF night, but I rarely just scan the HF dial due to ambient noise here in town.
