[GreenKeys] WU documentary from 1956

[Jim Haynes]

Another W.U. film out there is titled "Telegram for America" 1951
  And other things will show up with a web search.

You can see lots of pictures of WU hardware in the Western Union Technical
Review that is online, and also in "Western Union History of Technical
Progress 1935-1945"  They had a lot of stuff made for them by contract
manufacturers and a some in-house at the Chattanooga Works.  For typing
reperforators they preferred a design that used 7/8" tape and printed on
the edge, rather than Teletype's printing on top of chadless tape.
Kleinschmidt also manufactured printing perforators using 7/8" tape.

W.U. made their own tape readers, some of them motor driven and some
stepped by electromagnets.  The latter goes all the way back to early
time-division multiplex systems.  A late example is the "loop gate
transmitter" which holds a portion of tape that has been read in a loop,
and then can have it brought back over the sensing pins to be read
again.  This solves the "routing indicator absorption" problem in
automatic switching systems.  The problem is that you need to read
the routing indicator to know where to send the message, but then you
want to send the routing indicator as part of the complete message
after you have already read it once.

WU had a nice keyboard perforator that was motor driven, none of the
banging electromagnets of the Model 19 punch.  These were made on Model 
14 keyboards.  I don't know if W.U. had a surplus of scrap teleprinters
and got the keyboards from them, or if there was some other reason for
using the Teletype keyboard.

The History of Technical Progress chronicles the Pre-WW-II projects
to build their own teleprinters and other things to avoid spending so
much money with Teletype Corp.  Best known to hams probably are th
100-series of teleprinters, built of typewriter parts and having the
paper platen move from side to side like a typewriter, and like Teletype
Models 12 and 26, which makes it hard to feed roll paper.  The 100
series machines were supplied in "mailbox" style floor cabinets and also
in table top cabinets.  There was the 400 series of tape printers which
were a Baudot version of the circa 1930 stock ticker.  I don't know if
these were made from recycled stock tickers or some other way, but
either way it had a lot in common with Teletype Model 26.

One reason you don't see much Model 15 and 19 equipment in the video is
that most of the pictures involve W.U. offices rather than customer
premises equipment, and the whole telegram business made much use of
tape printers.  Page printers were more popular in customer's offices
so the customers would not have to deal with gummed tape and telegram
blanks.  But then it was necessary to have tape-to-page converters
to format tape messages for page printing.

Someone mentioned 50 baud, and there is reason for some confusion about
that.  The Bell System, U.S. military, and others transmit Baudot as
7.42 code, which works out to 368 operations per minute or about 60 wpm.
Teletype printers were designed to accept 7.00 unit code and W.U. 
preferred that because it increased speed to more like 65 wpm.  50 baud
operation tends to use 7.50 code which also comes out close to 67 wpm.
So if you are going to talk about 65 wpm equipment you need to be careful
whether you are talking 45.45 baud 7.0 or 50 baud 7.5

So most W.U. stuff ran at 45.45 baud, 7.00 unit code.  Then they 
introduced Telex to the U.S. and that was done with European made
equipment where 50 baud was standard.  And they had Teletype make 50
baud equipment for Telex use.

Just as an aside, the 3 U.S. military services each tended to go its own
way, and that was certainly the case with telegraph systems.  The Air
Force used W.U. Plan 55, Teletype machinery.  The Army used Kleinschmidt
machinery and a switching system done by Automatic Electric Co.  And
the Navy used a system developed by Bell Labs, with Teletype machinery.

 	---

 	"Ya can argue all ya wanna, but it's dif'rent than it was."
 	"No it ain't! No it ain't!  But ya gotta know the territory."
 		Meredith Willson, The Music Man