Back in the 70’s I met a fellow down in the Dallas area that made a box using a UART and a bunch of other chips on about 4 different boards that did speed conversion.  I could run 100WPM in and 60/75 out but it wouldn’t take any time to cause the buffers to fill up and then you got garble.  Or you could run 60 wpm in and get 60/75/100 wpm out.  I sold it off years ago when I got rid of my model 28 ASR.  Called something like a UT4…. Don’t even have any of the paperwork on it anymore.  That was a nice box.  It worked great when doing picture exchanges up on 20M.  It was basically a regenerative box but with the clock and UART in it it did nice work.  I think there was a writeup on it in RTTY news but don’t remember for sure.

Larry W0OGH

Sent from Mail for Windows

From: Jim Haynes
Sent: Friday, February 24, 2023 3:55 PM
To: Jeff G
Cc: [email protected]
Subject: Re: [GreenKeys] Model 28 Baud Rate Change

Hearing a question like this always prompts me to suggest leaving the

machine geared for 75 baud and using an electronic speed converter to

accomodate other input speeds.  I believe some of the Dovetron demods

might have such a part installed.  In any case you could use an old

fashioned 40-pin UART IC to do the conversion.  Or what we did before

we had UARTs was to make a speed converter out of small scale ICs.

Such as written up in Ham Radio magazine December 1971 p. 36.

Now if it's a KSR there is the Irv Hoff gadget that down-converts

the keyboard signals and has buffer so you don't overrun the slower

transmitter.  Look for UT-4 in RTTY.

               ---

               "Ya can argue all ya wanna, but it's dif'rent than it was."

               "No it ain't! No it ain't!  But ya gotta know the territory."

                               Meredith Willson, The Music Man

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