Back in the 80's, there was a very close analpore 1/2 mile down the hill from me whom pissed-off two states, four counties, and every town he'd visit. He even ran fake call signs on the 10M band, and back then you could get away with it, for a while. However, even when he ran so-called barefoot power, he still spurred a harmonic at X5 the fundamental FREQ. i.e., CB CH19 = 27.185MHz X 5 = 135.930MHz. I had a scanner that did AM aircraft band, so when that dude keyed up on CB CH19, I knew it right away over the scanner. A bit more difficult on CH38 LSB, but you could still do that to tell that someone very close is keying up there. 27.385MHz X 5 = 136.930MHz. When the scanner stops and unsquelches on SSB in AM mode, then you'll know he's there. And, when these dudes ran power with CB's, they almost always kick spurs more into the aircraft VHF band. Hey, no doubt that he covertly monitors YOU, so here's a way to keep monitoring HIM. Certainly nothing illegal about monitoring that way. Oh BTW... Don't have a scanner that does AM aircraft band? Then try an analog tuning FM receiver at the very end of the dial, i.e. 27.185MHz X 4 = 108.740MHz. Many of the older analog receivers can go there. If anything, this is a nice experiment to show and learn how harmonics work.