[Milsurplus] Strange signal on ~3595 kHz

[KD7JYK DM09]

"What does M89 mean?  I found a big list of "numbers stations" with 
codes like this but no explanation of their significance."

Try here, this explains the beginnings of the designations:

http://www.signalshed.com/docs/ABBREV.pdf

This is more in depth, but in short, the M is for Morse:

http://www.signalshed.com/docs/ENIGMA%202000%20Active%20Stations%20List%20V1.3.pdf

More info here:

http://www.signalshed.com/

There is also a couple of email reflectors dedicated to these:

http://mailman.qth.net/mailman/listinfo/spooks

and

Well, the other one appears DOA...  Spooks is pretty good, I've been a 
member since 1997, or so.

Kurt