[GreenKeys] Keyboard Reperf Wiring

Mon Dec 28 09:12:06 EST 2020

Many, many thanks for the responses I’ve gotten from many of you while I’m trying to get a good picture in my head of putting a many times modified over the years ASR back into something closer to a factory configuration.

As Nick mentions below, the reperf is not hooked in to the K-KT-T switch and the “normal” ASR had just a perf, not a reperf.  So the reperf was a later addition to the ASR, but to me anyway, Teletype did a very poor job of integrating it into product line, especially on the lines of documentation, especially considering the reams of documentation that was their norm.  See the attached JPG that I captured from page 241 of a 700+ page document found on Nick’s Navy Radio pages:  http://www.navy-radio.com/manuals/tty/28ASR-0967-LP-625-5010-7901.pdf

Notice  the explanation of machine operation while in the K-T position of the switch, that it says the “reperforator is actuated electrically and may be used, as can the typing unit, to record received messages.”  It then goes on to say “Reperforator may also be actuated mechanically.”

I have been unable to find any documentation from Teletype about how the reperf is electrically connected.  If it can be used to record received messages, then it must be driven by the loop that drives the typing unit.  What then becomes confusing, to me at least, is that if it may also be actuated mechanically by the keyboard, then typing would seem to also send a signal from the keyboard contacts that goes to the typing unit loop, which in turn drives the reperf.  So it is like the reperf gets the character typed twice.  Once in parallel from the codebar extensions and also serially via the loop.  Am I completely lost?  I think so.

I do have a cabinet and base here that has become a parts machine that has a “Perforator” mounted on it.  I guess I could use that and not worry about using the repef that is in question.  But I would really like to be able to punch tape on a received message.  Hmm…  Aux reperf?  What another can of worms!

I really appreciate the effort all have undertaken to help me get to the bottom of this endeavor.

Steve G./N4TTY

From: Nick England <navy.radio at gmail.com> 
Sent: Monday, December 28, 2020 7:42 AM
To: Steve Garrison N4TTY <N4TTY at arrl.net>
Cc: Greenkeys <greenkeys at mailman.qth.net>
Subject: Re: [GreenKeys] Keyboard Reperf Wiring

In my 28ASR experience and reading, the reperf is NOT hooked into the K-KT-T switch at all. As with anything Teletype, there are 999 variations. The "normal" ASR has a perf, not a reperf. (n.b. perf means no selector magnets). If there is a reperf, it is on a separate circuit and the ASR treats it like it is merely a perf. Of course, for the reperf you have to either mechanically clip the armature in the marking position or hook it up to a loop so it stays marking. Tom's switch schematic looks like a good way to control an ASR reperf so that you can copy incoming messages to the printer and reperf at the same time. 

The K-KT-T switch shaft has a cam that mechanically engages the keyboard code bars to the perf punch slides in the KT and T positions. In the KT position, the keyboard transmitter clutch operates and the tape is also punched. This operates at 60wpm or whatever your gear speed is.

In the T position, the keyboard transmitter clutch does not operate, the transmitter stays marking, and the keyboard code bars mechanically activate the perf. In this mode you can type quite a bit faster than 60wpm and cut tape while the printer is printing an incoming message. One of the 999 variants has a cam that only activates the perf in T mode, not in K or KT (that machine had me buffaloed for a while).

http://www.navy-radio.com/manuals/tty/28asr-kt-switching.pdf

Have fun,

Nick England K4NYW
www.navy-radio.com <http://www.navy-radio.com> 

On Sun, Dec 27, 2020 at 8:40 PM Steve Garrison <steve.n4tty at gmail.com <mailto:steve.n4tty at gmail.com> > wrote:

OK folks put your thinking caps on.

Now that I’ve begun to get a handle on how my ASR is wired, I can’t find out how the keyboard base reperf is wired in so it responds to signals when the K-KT-T control is in the KT position.  The reperf in my machine just had 4 wires, two of which got to the series connected selector mags on the reperf, just dangling in the back of the ASR.  Not hooked up to anything.

Ideas welcomed.  And I’ve been unable to find the proper WDs.  How about it Nick?

Steve G./N4TTY

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