[GreenKeys] Model 28RT puzzles

[Don Robert House]

Yes Nick,
I read all of it.

I originally got that unit from Tom Kleinschmidt as a spare for the
RT Cabinet that is at the museum in San Diego.  Since the cabinet
already has two factory wired units in it, I shipped the RT spare to
George Hutchison.  He did not have time to do anything with it and
drove the unit back to me last October.  We met in a dark parking
lot in Rockforfd and he gave me back the RT unit as well as a
military rectifier for a model 19. I have sent a photo of the two of us.

Since the US Navy was the biggest user of these beasties I
offered it to you if you would pay for the shipping, which you did.

The thing has travelled from somewhere unknown to Prospect
Heights, IL to Denver, CO to Needles, CA, to San Diego, CA to
Sequim, WA to Ringwood, IL and finally to you in Pennsylvania.

Hopefully you will finally get the thing operational.  Part of the
difficulty is that so much of the station wiring is in the cabinet.
Every installation is different.  I sent you several manuals but
apparently none had the drawings in them.

Good luck buddy... Fair winds and following seas...

Old Don
K9TTY
Currently in a Tornado Watch...

P.S.  Has anyone heard from Tom Kleinschmidt?
Perhaps he is just mad at me???



On 22 Jul 2010, at 8:17 PM, Nick England wrote:

FYI update

---------- Forwarded message ----------
From: Nick England <navy.radio at gmail.com>
Date: Thu, Jul 22, 2010 at 9:16 PM
Subject: Re: Model 28RT puzzles
To: Greenkeys <greenkeys at mailman.qth.net>


What a great list! - Riceguys sent a wiring diagram, and Jim and Tom
also provided info that helped me get much less confused. OK, I think
it goes like this -
1) The capacitors hook onto the AC line to indeed provide power factor
correction - for the shaded pole motor that is located inside the tape
bin (oops, I took that bin off long ago and forgot that motor was
inside). The "extra" 3-pin cinch connector plugs into the bin motor.
2) The lamp transformer plugs into the AC line from the top deck - the
extra 2-pin connector wired to it feeds the caps and tape bin motor.
3) That leaves the TD clutch relay circuit connector hanging free -
This connector is in series with the AC line feeding the 48vdc relays
and it must have been hooked up to what?  - a big resistor? a light
bulb? a rectifier diode?

Many thanks guys. I'll post an update when I get it singin' and
dancin' - probably a candidate for a You Tube video.

cheers,
Nick

On Thu, Jul 22, 2010 at 7:28 PM, Nick England <navy.radio at gmail.com>  
wrote:
> I have finally moved my 28RT up on the bench to get running. I have
> photos of this unit at
> http://www.navy-radio.com/tty/28rt.htm
>
> Sidenote - For those not familiar with the 28RT, it is a FIFO - an LPR
> printing reperf followed by a tape bin and then an LAXD climbing head
> TD. Both have gear shifts so you can run signal in at say 100wpm,
> punch the tape which spills into the bin while the TD reads it back
> out at say 60wpm. Or vice-versa.
>
> My first step has been tracing all the wiring to see how some previous
> owner had set things up. I have most everything beeped out but I am
> still puzzled by a few  things so maybe someone on the list can help
> un-puzzle me. I got this 28RT from Don House and it may have been in
> the hands of one of you other guys at some point....
>
> Situation -
> #1) On the LPR/LAXD top deck there are two cables with 2-pin female
> Cinch connectors which are meant to run somewhere. One is factory
> wired 115vac from the on-off switch and the other is homebrew-wired in
> series with the two LAXD clutch coils, a toggle switch, the
> distributor stop switch and the 115vac line. The LAXD clutch coils
> (reader and distributor) are wired in parallel and according to the
> docs are supposed to operate on 48vdc (160ma ea.).
> #2) There are two 15 uf oil capacitors (rated 600vdc/330vac) mounted
> in the bottom of the base (near the tape reels). They are wired in
> parallel and the leads run up to a 2-pin male Cinch connector mounted
> on the lamp transformer bracket (see #3 below). These are pretty
> clearly factory items - brackets, wires in plastic tubing, etc.
> Homebrewer has added a 3-pin female Cinch connector in parallel with
> the factory male 2-pin.
> #3) There is a bracket on the upper part of the base with a
> transformer whose secondary feeds 3 small lamps. The primary is
> connected to a cable with a 2-pin male Cinch connector. Bracket,
> cable, etc. all appear to be factory items. Homebrewer has added a
> 2-pin female Cinch connector in parallel with the factory male.
> #4) Note - There is also a 4-pin Cinch connector that carries leads
> from a tape-out switch on the reels - it all looks stock and obvious
> in function.
>
> Photos of these cables are near the bottom of
> http://www.navy-radio.com/tty/28rt.htm
>
> Now the 64,000 baud question - where should those two cables from the
> top deck go? and why?
> A) The 115vac cable from the top deck clearly hooks to the capacitor
> connector - so the two caps are in parallel with the AC line (really?
> power factor correction?)
>
> B) The other (home-brew) cable from the top deck evidently goes to the
> lamp transformer primary so it is in series with the TD clutch coils.
> That's weird.
>
> It is NOT posible to swap these two cables - the homebrew cable in the
> top deck is too short to reach the capacitor plug.
>
> And what about those extra home-brewed connectors? - one in parallel
> with the caps and one in parallel with the lamp transformer primary.
> What might they have gone to?
>
> I am assuming that this isn't random re-wiring by Mr. Homebrewer -
> other stuff in the signal circuits make sense and the caps and
> transformer are clearly factory items - but for what?
>
> Any suggestions or info greatly appreciated. I really like to
> understand why/how gear is originally constructed before I go in and
> make my own mess of things.
> Thanks gang,
> Nick K4NYW
>