M-209, for those of us who weren't born yet, is a US military mechanical code machine slightly resembling a 6-rotor, patch board-less version of the better known German ENIGMA.
Here's the full release from Richard Dillman of MRHS:
KSM will broadcast messages encrypted with the military M-209 crypto machine via RTTY on 26 April and 3 May.
The idea for the broadcast came up in conversations between myself and Dave Ross as a way for the MRHS to support the Military Radio Collectors Group meet taking place in San Luis Obispo, CA on 2-3 May. We thought it would be fun to give the attendees something to copy on their vintage military RTTY gear and then exercise their M-209 skills by decoding the message. But we thought other listeners may enjoy trying their hand at decoding the message as well, thus this announcement (see below for information about a M-209 emulator in case you don't have access to the genuine article).
MRHS transmitter engineer Steve Hawes, who manages our RTTY broadcasts, was keen for the idea and Dave provided the text so all the pieces are in place. Here are the details:
Dates: 26 April and 3 May
Times: Approximately 1200pdt and 1400pdt
Modes: RTTY and FEC. Baudot transmissions are at 170cps shift, 45 baud. FEC transmissions are at 170cps shift, 100 baud
Frequencies: 8433.0kc, 12631.0kc
Text: Dave's text will start with a plaintext preamble and will include the settings for the M-209 as well as the key. That will be followed by the encrypted text in five letter groups.
MRCG - http://syzen.com/milradio/
M-209 emulator for those who wish to participate but don't have a M-209 -
MRHS - http://www.radiomarine.org