Yesterday afternoon I did some VHF low scanning, California Highway Patrol was booming in, among many other users. Also heard a fair amount of above 30 MHz Latin American traffic (mostly taxi cabs). Fort Hood, Texas Range Control on 30.450 MHz FM [150.0 Hz tone squelch] was also full scale. SNOTEL data on 40.670 MHz FM [CSQ] and the BNSF rail data link system was going nuts on 44.580 MHz FM [CSQ]
34.1500 MHz FM [150 Hz] Had a strong FM signal on it, with that little 150Hz hum in the background, but no audio that I could make out. Signal was there for well over an hour (this is around 2:00 in the afternoon US Eastern time, in downtown Richmond VA). I did manage to get a few video clips of it, along with some of the other activity.
In the past I've heard somebody left the radio on transmit mode before - usually on the 30.000 MHz frequency, but 34.15 FM is a new one for me. I will do some digging and see if that's a known range control, etc. frequency at a US military base.