1. Introduction

1997 Ary Boender and Klaus Betke for the first time described a Morse station transmitting continously on 3486 kHz. They concluded the station was located in Zilina 49,27°N 18,76°E (Slovakia), a rather important town, because of its industry and University. It was, and I think, still is, home of the Technical Dept. of the Academy of Transport and Communication, a MIL institution. Zilinas airport is used both by civilian and military aircraft.

Apart from FSK modulation in Latin Morse alphabet, a second information apparently was transmitted in Pulse Duration Modulation (PDM). In those years a very advanced technology.

Since then the Warsaw Pact has fallen apart and former Czechoslovakia was split up in the Republics of Czechia and Slovakia, both NATO members. The transmissions however still can be heard, although considerably resized. We still do not know more about the purpose of the station or its operators.
The European Number Stations Group assigned the code M62 to the station and today still keeps record of it. Like M51 or M22, M62 is not a Number Station, it has typical characteristics of CZ/SK MIL networks.

There was a similar Czech network which used 2852//2362 kHz for some years. It disappeared in April 2004. A connection of the two stations is quite probable.

2. M62 since 1999

My first records are dated 1999 and continue until today (2007). It seems, the special modulation has been abandoned, I always found just a normal FSK modulation using the Latin Morse alphabet. I think, M62 was not a Warsaw Pact station, it would have used the Cyrillic alphabet.
1999 a second frequency on 1732 kHz was found, until December 2003 this was the parallel frequency to 3486 or 4396 kHz. The station continued 24/7/365 with the same skeds.
Then, 2004, 1732 kHz was switched off again (or its power reduced). Since then skeds and frequencies changed again and in 2006 the transmissions became erratic, only audible in the European mornings. Text and message formats have, in all the years, not changed.

3. Skeds and Message Formats

Three message formats have been logged

- old marker roundslip "J7XD J7XD J7XD = D3QK D3QK D3QK+"
- new marker roundslip "QWD8 QWD8 QWD8 +"
- operational messages like "== QTR 0900" or " == QSA? 669"
- messages with 20 or 30 groups.

Roundslips
J7XD is the addressee, D3QK is the sender. QWD8 is the adressee.

Operational messages
They indicate local time, ask the quality of reception or consist of a series of trigrams of unknown purpose.

Messages
== RFDP QTC 884 = 1 20 23 1013 884 = RFDP = 5LG x20 = N8IR (msg repeated) == for RFDP rpt QLN +
This is msg 1 of the day with 20 gr sent at 1013 local time from N8IR to RFDP. Reading back via secure channels is required.
The next msg will consist of 20 5FG and in the third msg after one gr of 5F will be followed by two gr of 5L. 884 will normally be used that day, it is the adress (command, branch). "for RFDP" may indicate the msg is received somewhere and should be forwarded to RFDP.


Schedules
As stated above M62 was heard 24/7/365 with its marker, messages have not been copied. For long periods a parallel frequency was noted. The station changed its callsigns at 0000h local time the 1., the 11. and the 21. of each month. Six sets of callsigns were used in turn. Frequencies 3486//1732 or 4396//1732 kHz.

Since 2000 new sets were introduced, still no msgs. Then, 17.8.2003, I heard the first message and the transmitter was regularly switched off. In 2004 1732 kHz disappears and the transmissions become erratic. Callsigns now are valid one day.
Since May 2005 M62 can be found with some luck on 4396 or 5232 kHz, but other frequencies have been used as well. Good reception chances are in the European mornings Monday and Wednesday. The first message normally is due around 0700z, around 4 are sent until 0900z; transmission stops between 1000z and 1100z. Always count with exceptions.
The marker is auto-keyed, very slow, (all?) messages are hand keyed.

4. Open Questions and Latest News

The fact, that M62 survived all political and military changes proves it is still of importance for its operators. Why does the Slovakian MIL use a Morse HF Link in a small country? Are the transmissions heard abroad? M62 does not behave like any other number station. Three similar networks, all operated by the Czech or Slovakian MIL, have stopped transmissions years ago - not so M62. An exercises network? Who knows?


2007 the transmissions became erratic and after 0900z 17.June 2007 I didn't hear the station again.
The last messages were transmitted between 0727z and 0833z from ESUC to the addressee S5GK on 5232 kHz.


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