27.70125 MHz FM On-Off Keying? W3HFU SDR (900 ft sky loop) 1937 UTC 10 Dec 2024

[R4002]

27701.25 kHz FM.  Right on frequency.  Transmission duration variable, from around 1 second, to 2-3 seconds, to 8-10 seconds.  No modulation noted, given the frequency choice, which is UK FM CB radio channel 11, I'd say somebody is checking SWR or otherwise testing.  No SSTV signals noted at the moment, but when the band is hopping, the 27.700 MHz USB SSTV traffic often "beats" UK FM signals on 27.701 FM, add some SSB QRM and taxi cab dispatchers on 27.705 MHz AM and you've got a winner.

At 1939 UTC, Spanish language comms on 27.705 MHz LSB noted, followed a few moments later by some weak SSTV (transmission started in the last 10 seconds or so of 1939 UTC, going strong at 1940 UTC.

27.710 MHz LSB is also going nonstop with single side band voice chatter, Spanish language, likely South American.