[GreenKeys] Fwd: M28 reperfs

Tue Jun 3 13:08:48 EDT 2025

DUNCAN'S KEYBOARD TYPING REPERF
This was a garage rescue so it might well be a mongrel inside a TT-253A
case.
Maybe it is a TT-253F where F stands for Frankenstein?

FEEDOUT
IIRC, there was an automatic version that would feed out some length of
LTRS after X cycles of MARK. And there were some that were operated
remotely (switch key on keyboard). The 200 ohm 252M magnet says 100madc
when used for keyboard sync pulsing- but I also see 200 ohm coils saying
50madc or 115vac.
https://www.navy-radio.com/tty/tty-magnets.htm
My impression - If the LPR reperf is a marvel of impenetrable mechanical
complexity, the tape feedout mechanisms are icing on the cake...

MODEL NUMBERS
The magical document that lists characteristics of each model number
(apparatus code) is called an Analysis Chart - unfortunately I have never
seen one for the LPR reperf. These came from Jim Haynes -
https://www.navy-radio.com/tty/apparatus.htm
The Apparatus Code chart is something I started to try to fill in blanks.
It needs updating - any additional info is greatly appreciated,

For models with Bell designations (28A, 28B, etc.), This document provides
info on the various configurations, often with the corresponding Teletype
model number (LPR4AWA, LPR7AWA, etc.) - see page 89 for some LPR info. But
nothing on LPR13...
https://www.navy-radio.com/manuals/tty/28-we-rs.pdf

CHAD DISPOSAL -
If the reperf isn't fitted for a vacuum and storage bag, the chad is
directed out of the bottom of the unit - check this reperf description -
"This unit, which produces fully perforated tape, is designed to mount on a
28D typing reperforator base which in turn mounts on a 28A typing
reperforator table. The table must be modified to accommodate a chad
container.
Features of this unit are a chad chute which has an opening on top for
clearing out chad in the event of a jam, a chad container for mounting on
the table, and 31 point male & female connectors."

See page 13 of this parts book showing the 176615 chad chute/box
modification to the table
https://www.navy-radio.com/manuals/tty/1172B-6710-ch5.pdf
The instructions are in Specification 50050S which I don't have
"50050S- 176615 kit to adapt 28A and 28D bases for use with typing or non
typing reperforator containing a fully perforated punch mechanism"

Yours in teletypery.....
Nick England K4NYW
www.navy-radio.com

On Mon, Jun 2, 2025 at 10:49 PM Duncan Brown <duncanancy at earthlink.net>
wrote:

> Is there a document that lists all the different M28 reperf "LPR" models
> and  what is different about each?
>
> I'm working on a TT-253A (thanks to Nick!) that does not have a standard
> reperf in it.  The TT-253A is supposed to use a LPR53AWA (full perf, tape
> feed out, backspace).  What is in this unit is a LPR13XXX (chadless, tape
> feed out, no backspace). The unit punches fine (after I re-hooked up a
> spring in the Selector Magnet area), but can't check the printing yet due
> to missing print hammer (one on order from Nick).
>
> In checking out the "Tape feed-out" function - the tape feed-out solenoid
> operates (and buzzes) and the ratchets turn but no tape out. I think this
> is the version that tape-out is suppressed by incoming message (there is an
> arm going up towards the SM armature), but can't see why it is not
> releasing the function clutch when running closed.
>
> Also confusion between different manuals about whether the tape feed-out
> solenoid is supposed to operate on 115V AC or 115V DC.  1963 vintage
> manuals (eg NAVSHIPS 94456) show TT-253A using LPR53AWA reperf with
> solenoid L5850 (TC # 274); 450 ohms; 115VDC. Wiring diagrams show the LTRK5
> base with a series resistor & diode and parallel capacitor to supply the
> 115VDC. But this LTRK5 base has the resistor & diode replaced by wires and
> the capacitor removed.
>
> I thought that the removal of the 115VDC parts could have been a later
> modification. (Besides the change of LPR unit, this TT-253A had the power &
> signal lines soldered directly to the blue Amphenol 16 contact ribbon
> connector!) (I've ordered the mating connector)
>
> Then I got a hold of the NAVELEX 0967-LP-616-7010 (APR 79) manuals and
> they show the LTRK5 base and LPR53 wired for 115VAC!!
>
> I'm getting confused!
>
> The reperf in this TT-253A is a LPR13XXX, with a tape-out solenoid #252
> and measures 200 ohms and it does not look like any of the drawings in any
> of the manuals. (Pictures enclosed)  I've read how the tape-out mechanism
> is supposed to work, but had trouble following it, especially in that my
> unit seems different from what the manuals are talking about.
>
> When I energize the solenoid, the timing ratchets rotate, but nothing else
> happens.  I've tried pushing & pulling (gently) the various levers in the
> area, but nothing trips the function clutch. I'll put in the parts to put
> DC on the #252 solenoid, but I don't think it will affect the tape-out.
>
> This dissertation was partly just to get my thoughts & facts together, but
> if anyone has any ideas about the tape-out mechanism, I'd like to hear them.
>
> Thanks,
>
> Duncan
> K2OEQ
>
>
>
>
>
>
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