Thanks Token, just done a search of the net and it appears L6YC is widely reported, as far back as 2005 and on 1.720MHz and mostly on 3MHz over the years.
Someone suggested on one site that L6YC is M94 Chinese group.
I see mention of it, plus reports by your esteemed self...on Numbers & Oddities newsletter via PDF. You sure get around the traps.
It went off air at 0958z too, not sure when it came back on as I move around the band looking for the unusual. Thanks for the heads up on Chinese Military...Jack.
M94 would not be Chinese, that would be South Korean, however M94 has not been active for a couple of years, and did not use this format. I would be interested in knowing what site suggested L6YC might be related to M94, still got the link?
Looking at Numbers and Oddities newsletter #180, Sep 2012, shows L6YC on the same freq, 3860, with the same format, on air H+15 to H+25 and H+45 to H+55. Speculation then was Norther China or far western Russia, both fit my direction of arrival (from here they are on the same bearing).
Looking further back to 2005 the same signal was thought to be Russian. The earliest mention I can find of this freq used with this callsign (L6YC) is in Feb of 2005, so it has been around a while.
In 2011 the same freq was used with the same cycle but callsign KTR4.
Numbers and Oddities has assigned the temporary designation UM-10 to this signal, and has noticed it on many frequencies with many callsigns.
Next time you hear it you might look at 3207 kHz and see if you have it on that frequency also. That frequency has variously been reported as 3205, 3206, or 3207, I suspect all but 3207 are errors on the part of the reporting parties.
Since this station appears to be being followed primarily by the numbers folks I am going to move this thread to the Spy Numbers forum, although I suspect it is mil, not spy.
T!