Long story, try to make it short. I started working in a 2-way shop, 1988, in Newington, NH, near Pease AFB. Boss told me this:
The Commander level officers had a VHF-Hi frequency that sometime in the 1980's started picking up sounds of baby crying, man & woman conversation, footsteps, etc. AF & FCC techs finally converged on base, did some DF'ing. Located it to base housing. Knocked on some doors, a woman answered at one duplex. They explained why they were there, what they'd heard, (at which point she blushed, extremely), asked if she had any new electronics. She said they had a night-light/baby monitor, for their new baby. Techs started looking at their spectrum analyzer, yup, that was the source. 3rd harmonic of the 49 MHz operating frequency was wayyyy stronger than the carrier, which was wandering all over the place!!!
They asked where she got it? "At the PX (Post Exchange)"
Duly tromped over there, tested all the cheap chinese baby monitors there, they all failed same way.
Oooops.