[GreenKeys] Model 28 Compact TEMPEST KSR AN/UGC-77 manual

[Nick England]

The conversion to low level +/-6v signaling is done in an external
gold-colored box called an ESA. Usually mounted nearby for 28KSR and 28RO
and in the base for 28ASR.
The machine’s selector magnets are shielded and driven by electronics in
the ESA via shielded cable and military-style circular connector. The
keyboard or TD transmitter contacts are gold-plated because they carry very
little current which is then converted to +/-6v signaling in the ESA. The
UGC-77 KSR is unique in using photocells for keyboard encoding and the
distributor. Again that signal goes to the ESA.
Photos and info here
https://www.navy-radio.com/tty-tempest.htm
https://www.navy-radio.com/tty/ugc77.htm



On Mon, Feb 13, 2023 at 10:58 PM Jeffrey Golas <jeffg at junknet.net> wrote:

> Is there an easy way to identify low level gear vs high level?
>
> Jeff KC3GJX
>
> On Feb 13, 2023, at 9:18 PM, Nick England <navy.radio at gmail.com> wrote:
>
> 
>
> Thanks to the USS Iowa teletype gang, I have just scanned a Navy manual
> that covers all the 28 Compact units including the AN/UGC-77 TEMPEST KSR
> (the one with photocells) I have been looking for a UGC-77 manual for years
> - now I can see if my homebrew schematics match Teletype's official ones!
> https://www.navy-radio.com/manuals/tty/28compact-man.htm
> This manual refers to high-level (UGC-20, UGC-25, etc.) and low-level
> (UGC-77, etc.) in the parts list and schematics.
> I have also pulled out the wiring diagrams for the low-level units here -
> https://www.navy-radio.com/manuals/tty/wd/28compact-tempest-wd.pdf
>
> Cheers,
> Nick England K4NYW
> www.navy-radio.com
>
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> --
Nick England K4NYW
www.navy-radio.com
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