Nifty! I found the original plans this appears to be built from, or at least a very similar "solid state fox box" circuit, on page 30 of the November 20, 1976 issue of Ham Radio Magazine:

https://archive.org/download/hamradiomag/ham_radio_magazine/Ham%20Radio%20Magazine%201976/11%20November%201976.pdf

What's the info printed on that white chip? I agree it looks like they "adapted" something in - thinking a comparison to this reference design could shed light on this.


Cheers,
Gillian

On Tue, Jan 24, 2023, 9:42 AM Jeffrey Golas <jeffg@junknet.net> wrote:
Thought you guys and gals might find this interesting...I volunteer on Battleship NJ and found this tucked away. Appears to be Navy-like but mentions "project" on it, serial #3 lol. Other than WMS on the board theres no manufacturer.

Its a RTTY/Teletype message generator that does the "quick brown fox" message. Whats really interesting is that all that is based on ONE chip whose sole purpose is exactly that. A MM5220DF. Other chips in that series have similar purposes, like ASCII-BAUDOT conversion.

Theres what looks like a white CPU, but Icant find any docs on it. It almost looks like something they had a surplus of, and with no rom, possibly wired it as a NOP (no-operation) so that it would just be an 8 bit counter. I think anyway.

It does seen to work after cleaning all the switches, I plan to test on the loop. All it does is keying via a solid state relay. I tried piping my signal gen through it but Fldigi couldnt decode.




Jeff KC3GJX

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