-------- Forwarded Message --------
Subject:     Re: [GreenKeys] Interesting cipher machine.
Date:     Thu, 10 Feb 2022 15:59:22 -0500
From:     Duncan Brown <[email protected]>
To:     Michael Katzmann <[email protected]>



Michael,

Thanks for the link!!

I was not aware that NCM had a youtube channel - looks to be new.

The TTY in there is a TT-30/AGA-1 (aka Teletype Corp. Model 31). The box is a portable TTY and (SIGABA-type) encryption unit in one.  Never seen this version, but description enclosed.  There is a picture (enclosed) of the communications position of President Truman's VC-118 aircraft in 1947 using a similar unit.  (note the AN/ART-12 modified for RTTY on the shelf above.)

The original  "SIGABA" machine did not include a TTY.  It had a keyboard and just generated the encrypted signal typed onto a paper tape to be sent out over voice, CW or TTY. Later, there were modifications or adapters to generate the 5-bit TTY code directly. SIGABA was manufactured by Teletype Corp. for the government.

 I believe the proper nomenclature for the AFSAM 4A was "SIGNIN" and "M-294"

Thanks  & have fun,

Duncan
K2OEQ