[GreenKeys] 28ASR K-KT-T perf strangeness?

[Nick England]

FWIW - Info for the archives -
OK, at least I have figured out a few things about how this works from
looking at the machine and reading the Navy C-school maintenance course
which covers the UGC-6K -
http://www.navy-radio.com/manuals/tty/tty_maint_school.htm
1) In K mode
    - the TD clutch is not energized
    - the Keyboard Pulse magnet is energized - allowing the keyboard clutch
to operate
    - the perf is not engaged
    - result => Keyboard transmits through typing unit.
2) In KT mode
    - the TD clutch is energized
    - the Keyboard Pulse magnet is energized - allowing the keyboard clutch
to operate
    - the perf is not engaged
    - result => Keyboard and TD transmit through typing unit.
3) In T mode
    - the TD clutch is energized
    - the Keyboard Pulse magnet is not energized - the keyboard clutch does
not operate
    - the perf is mechanically engaged by the keyboard (the keyboard is
reset by the perf)
    - result => TD transmits through the typing unit. Keyboard punches tape
without transmitting

Discoveries along the way -
a) Because of the alternative cam, the perf does not operate in KT mode,
unlike a "normal" ASR.
b) Because my Keyboard Pulse magnet was mechanically disabled, the keyboard
clutch was operating in T mode, unlike a "normal" ASR

I still have no idea why my LTPE1 is a reperf (with selector magnets)
rather than a perf.

Nick England K4NYW
www.navy-radio.com


On Tue, Oct 23, 2018 at 2:52 PM Nick England <navy.radio at gmail.com> wrote:

> I am restoring an AN/UGC-6K (28ASR with aux reperf).
> Strangeness #1
> This 28ASR has an "LTPE1/AWA" keyboard typing perf installed - but it is
> actually a typing reperf with selector.
> I thought LTPE meant typing perf only - this perf/reperf is badged
> LTPE1/AWA and TT-252/UG (the correct military nomenclature for LTPE1/AWA).
> The LTPE1 badge is riveted in place so it probably isn't a case of someone
> switching tags. Did someone once add a selector to an LTPE? That seems like
> a horrible unnecessary job, swapping camshaft, etc. etc. etc. The selector
> wiring goes to a 32-point connector and also an external cable - both are
>
> Strangeness #2
> The keyboard/base says it is an LAK42/ARN
> K and KT mode both mechanically disable the perf - only T mode releases
> the code bar extensions to trip the perf.
> T mode acts like I'd expect KT mode to work - the perf punches AND the
> keyboard transmitter transmits. In a normal 28ASR the T mode means local
> perf only with no transmitter.
>
> So am I dealing with strange out of sync cams on the K-KT-T switch shaft?
> Or are these some weird modes only found on this model?
> The LAK analysis chart doesn't mention anything weird like this for
> LAK42....
>
> As always, any clarification of my poor confused brain is greatly
> appreciated.
>
> Cheers,
> Nick England K4NYW
> www.navy-radio.com
>
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