[GreenKeys] Re: Western Union Model 21A

[Don Robert House]

Thanks Jim,

I had hoped you would respond.  You are probably right on with the W.U. 21A
I reckon the manufacturer or contractor meant little to the radio operator.

Don

>I believe we have somewhere that there was a Model 13 consisting of a
>Model 12 typing unit with a Model 10 transmitting apparatus.  Apparently
>the Model 10 printer was excessively costly to manufacture and the Model
>12 printer from Morkrum-Kleinschmidt fit right into the scheme.
>
>There was a Model 17, which was a Hellschreiber sort of machine.  I don't
>know whether it was compatible with the German Hellschreiber.
>
>There was a Model 24 which preceded the 26 and was similar in appearance.
>My understanding is that the 24 lacked overlap, or something like that,
>which was added in the 26.  Hence the 24 didn't get into the field.
>The 24/26 machines were based on the design of the stock ticker which
>went into service in 1931, replacing the old glass bell jar tickers.
>I don't think the stock ticker had a model number, but I may be wrong.
>The stock ticker was of course a tape strip printer using 6-level code.
>Later Western Union made some printers they called 401A which was a
>5-level tape strip printer very similar to the stock ticker.  I would
>guess they might have used Model 26 parts and old tickers to make the
>401A, but that is just a guess.
>
>My understand has always been that the intention of the Model 26 was the
>same as the Model 33 - to have a lower-cost (than Model 15) machine for
>those TWX customers who didn't use it a lot.  Hence trying to run a
>26 for 24 hours a day was a misuse in the same sense that using a Model 33
>for a computer console is a misuse; but no doubt some people tried it.
>I guess it didn't work out because the cost saving was not large enough
>to justify having two different sets of spare parts and two different
>sets of repair skills.  Model 26s came into amateur radio at a time when
>Model 12s were still widely used and Model 15s were hard to come by.
>
>There is a well-known 21A printer, but I think that might be a Western
>Union number rather than a Teletype model.  (Model 14s were called 2A
>and 2B by Western Union; and they also had a 1A and 1B which were made
>by Kleinschmidt before the merger with Morkrum.)  This is a tape strip
>multi-magnet printer used to receive from time-division multiplex.  It has
>some parts in common with the Model 14, mainly in the tape path.  The
>cabinet looks like a Model 14 cabinet squeezed down.  The code bars and
>pull bars are in a flat arrangement rather than curved.
>
>Model 29, according to the Slayton document, was a 6-level printer like
>a 28 intended to replace the Model 20.  But it didn't sell, so few were
>produced.  What was produced and most of us called a Model 29 was a
>6-level machine in computer BCD code.  There were both RO and ASR
>versions.  I have seen a title of "Model 28 IDP ASR set" (Integrated
>Data Processing) on some documents for that machine, so I guess there
>is some indecision about what the model number was.  Supposedly these
>were used only within the Bell System; but some turned up in the late
>1960s in a surplus store in Oakland, and there were also some at G.E.
>in Phoenix.


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Don Robert House
North American Data Communications Museum
URL: http://www.nadcomm.org
Computer Museum of America
URL: http://www.computer-museum.org