I'm new here, found this forum after doing a search on these beacons. I kept hearing some of them in the CW portion of the 40 meter ham band. I guess no one really knows what exact purpose these beacons serve?
On 8/28 logged the "K" beacon on 7039 khz, 1501-1549 utc., along with a lot of guys chanting something in Tagalog or Malay.
I also heard three or four single character beacons on 7039-7040 khz (my DX-398 only has one khz readout) on 8/21, around 1336 utc: "K", "F", "M", and what sounded like an "O" also. From doing a bit of net research, it seems there is no "O" on 7039. Maybe it was a misread. There were also a bunch of dudes chatting away in Tagalog on and near that frequency.