Received via Wessex SDR (South West UK SDR). Lots of French language chatter...music and sound effect loops, and so forth. Some of the stations seem to be closer to 6660.1 kHz...in fact, 6660.06 kHz provided the best signal (for the guy who keeps transmitting the same 10-15 duration audio loop over and over again). Very good signals, peaking at S9+10dB. Most signals are solid SIO 444 though, very little QSB / fading.
This is a well-known and popular free bander frequency - that is, Echo Charlie or 45 meter band frequency - 6.6 MHz band. 6.660 MHz 6,660 LSB
45m band calling frequencies / working frequencies, there are many. At the time of this (1350 UTC, 1351 UTC)...only 6660 LSB is active. Of course, the aeronautical stations active on 6667 kHz USB, 6622 kHz USB, etc.
And...at 1352 UTC, another freebander popped up on 6635 kHz LSB, then 6633 kHz LSB for radio checks...now back to 6635 kHz LSB, calling CQ 45 meters, CQ 45 meters (in French).