[GreenKeys] M28 reperfs

Thu Jun 5 08:35:33 EDT 2025

I have gotten an impression (not backed up by analysis yet) that various
models used for CRITICOM applications (intelligence) were fully perforated
as well as being 7.00 instead of 7.42.

Why? I do not know, but the A B C model nomenclature may simply mean
different applications and not progressive improvement.

Nick England K4NYW
www.navy-radio.com

On Wed, Jun 4, 2025 at 9:45 PM Duncan Brown <duncanancy at earthlink.net>
wrote:

> Daniel,
>
> At least according to the documentation, the Navy used both chadless and
> full perf on both the TT-192, TT-292 and TT-253 series.  There were
> modification kits to add the vacuum chad removal, but it is not clear what
> they were replacing.
>
> What is strange (to me) is that they started out chadless and then went to
> full perf in later models (TT-192, -192A, -192B were chadless; TT-192C was
> full perf.  TT-253/UG was chadless and A-D models where full perf.
> TT-292/UG was chadless and TT-292A was full perf.)  Does this imply a
> problem with the chadless tape?
>
> Interesting that both of our TT-253As are chadless, although the LPRs
> could have been changed out at some point. What model reperf is in you
> TT-253A?  I have a LPR13XXX in mine.  i can't find anything about it.
>
> 73,
>
> Duncan
> K2OEQ
>
>
> On 6/2/2025 11:49 PM, Daniel Jones wrote:
>
> I wonder if the navy used both Chad and Chadless in these units.  My
> TT-253A has the chadless Reperf.
>
> Looking at the case I wonder how they dealt with the chads in units with
> the full punch.
>
> If you need more print heads let me know I have 50-60 still on hand from
> the batch I made a couple years ago and I can throw a few in an envelope
> for you and send them your way.
>
> Daniel
>
> Daniel
>
>
> www.K6YIC.com
> DJones at K6YIC.com
> HH#11973
>
> On Jun 2, 2025, at 19:54, Duncan Brown <duncanancy at earthlink.net>
> <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
>
>
>
>
>
>
> <LPR13XXX tape-out side.jpg>
> <LPR13XXX tape-out top.jpg>
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