[GreenKeys] AN/TCG-1A Available near Carson City NV

[Duncan Brown]

On 2/3/2025 12:34 PM, W2HX wrote:
>
> Wow. A thing of beauty! Looks like nothing on this model on Nick’s 
> site. Looks like, two typing reperfs (of the M14/M19 era vintage?) and 
> three TDs (later vintage?) Interesting unit.
>
> 73 Eugene W2HX
> My Youtube Channel: https://www.youtube.com/@w2hx/videos 
> <https://www.youtube.com/@w2hx/videos>
>

Eugene,

The AN/TGC-1 was the first "Torn-Tape Relay" equipment for relaying TTY 
messages.  Multiple units would be set up, side by side, for different 
circuits. A message would come in on a tape, an operator ("tape ape") 
would then tear the tape off of the reperf, read the header bits to see 
where it was going to, then walk the tape over to the appropriate tape 
reader to be sent out.


There were two M14 typing reperfs, "Receiving" and "Monitor." Incoming 
messages appeared on the "Receiving" unit.  The "Monitor" unit was used 
to record all outgoing messages. There are three tape readers (not 
really "TDs" because there is no distributor, the readers are serial, 
but otherwise, M14 type).

The first (left) tape reader was "Numbers". You can see a small tape 
spool beneath it. This was a tape punched with consecutive numbers. One 
digit from this tape was automatically read before any message was sent, 
thus numbering each messages sent. The other two tape readers were both 
connected to the outgoing line.  Tapes could be queued up so that when 
one tape finished, the next one would run (after a new number was 
sent).  The logic controlling all of this was R-squared-L (relay-relay 
logic) with at least a dozen multi-contact relays.

This unit was designed in the 1940s and used through the 1950s when it 
was replaced by units with more channels. I had always assumed that this 
was a Teletype Corp. product, but in the original manual "Tentative TM 
11-2203; 10 June 1944" all wiring drawings say "W. U. TEL. CO." on 
them.  The AN/TGC-1A that John showed has a nomenclature plate that says 
the manufacturer was "Molded Insulator Co."

You can see a Torn-Tape Relay station in action at this video: 
https://www.youtube.com/watch?v=hQG8VRSez_U    (note: no audio, video only)
This was taken at the US Signal Corps Major Relay Station in Phu Lam, 
Viet Nam in 1969.  The TTY equipment is the AN/TGC-70, which was a 6 
channel system.   On the video at 0:33, the text should say "Bank of 
Kleinschmidt Receivers" (not "Teletype").
I think the Univac 1004 must have been used with the "glass TTY" at the 
end for message corrections.

Have fun,

Duncan
K2OEQ
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