Interesting! The second set of numbers is 13 digits which apparently is the same length as the "FSN" code pre-1975, could relate to that somehow.

Also, someone earlier mentioned the white chip being a CPU - it's a UART. I saw that datasheet mentioning the 42 pin CPU, but this chip is 40 pins, not 42. Earlier today I found the second number is the actual part number and its a 40 pin UART that was common around that time, likely used to generate the 110 baud rate.


So...I hooked it up to the loop - no bueno. Its odd - it consistently prints the wrong stuff, meaning if I start it, let it print a line, stop it, do CR LF then start again, it prints an identical line, however its all gibberish. I don't think its a FIGS/letters thing either.

Other than printing two identical characters first (both asci/baudot have two CRs at the beginning of the message), there's no pattern that aligns to what it should be printing. I'm suspecting it's locked in ASCII mode - were there any teletypes that did 45 baud ASCII? Would anyone know how easy it would be to hook this up to a 33 to try? thing is I dont have a loop supply where the 33 is.

I may try hooking up my volpe board to the loop to see if that decodes it. If so I'll have my answer.

Jeff





On Tue, Jan 24, 2023 at 4:56 PM <hwhall@compuserve.com> wrote:
5815 maps to Federal Supply Classification (FSC) 5815 = Teletype and Facsimile Equipment.
Google hasn't made any sense out of the other numbers yet.

Wayne
WB4OGM

-----Original Message-----
From: Jeffrey Golas <jeffg@junknet.net>
To: Greenkeys <greenkeys@mailman.qth.net>
Sent: Tue, Jan 24, 2023 7:40 am
Subject: [GreenKeys] Navy Teletype Message Generator

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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