[GreenKeys] Navy Teletype Message Generator

[Jeff G]

 Ok I swear I googled the other number yesterday (S1883) and got nothing -
today I google it again and found that it IS a UART:
https://www.ebay.com/p/1201563377

The chip says "AMI 7548CP", then has "S1883 Korea" on it.

The 7548 number is likely the date code as this was definitely from around
'75.

Jeff

On Tue, Jan 24, 2023 at 10:55 AM Gillian Webb <thaeli at magfest.org> wrote:

> 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 at 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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