[GreenKeys] Telex/TWX?

[henning]

Hello Sam and others,

well, here some facts from Germany and other countries I know:

The Siemens company started the first automatically operated Telex network in 1931 between the two cities of Berlin and Hamburg. Soon it grew all over Germany and Europe.

It was derivated from the telephone exchange technology with rotary pulse diallers (what you in UK and other countries call Strowger selectors), but all based on current loop telegraph technology with 40 ma 120 volts. 
Lines from exchange to subscriber were mainly two wire single current, for logner distances in country side areas 4 (3) wire double current +/- 60 volts  40ma was in use. But double current was very rare. Although I have also never been professionally in Telex service I would say over 90 percent was single current subscriber line technology.
This whole systems was called TW 39 / TW 55 (from Teilnehmer Waehlsystem 1939/1955 which you could translate as subscriber dial up system).
This techology lasted in Germany until the mid 1970s. Then it was changed over to a kind of modem tone frequency system with unfortunately proprietary tone pairs (called System ED 1000) made by Siemens.
In order to use the old mechanical TW39 machines after system change, a kind of modem connected between the machine and the line to the exchange was need now. This ED1000 Telex system is still in use for the last remaining Telex subscribers here in Germany. Mostly banks and shipping companies. The total of still remaining Telex subscribers is estimated around 1,000 - 2,000.
In it's peak in the 1980s the German Telex network had over 150,000 subscribers.
Machines were only Siemens and Lorenz (SEL) machines. They were property of the subscriber but perfectly maintained by the German Post as maintenance of the machine was included in the monthly line rental fee.
Please see my website www.teleprinter.net for the models that were in use. It started from Lorenz Lo15 (licenced model 15) and Siemens T37 until the last Lo3003 and Siemens T1200.

In East Germany (GDR) a TW39 current loop system was in use until the reunification with West Germany. Then the East German Telex network was incorporated into the West German system.
Machines there were only RFT (of course ;-) ). Mostly mechanical RFT T51, which was a Siemens T37. 

Austria first also had a TW39 system Telex network. But later changed to a derivate of V.21 subscriber line tone system insted of using the German ED1000 system.
Additional to Siemens and Lorenz machines, there also Olivetti machines were in use. Network has been already switched off.

The Netherlands used also a TW39 system, but with keyboard (Baudot) dialling instead of pulse dialling with a rotary dialler.
In late 1980s they switched over to a V.21 tone frequency system. As far as I know their Telex also still exists.

Italy also used a double current TW39 system with keyboard (Baudot) dialling. Machines of course mainly Olivetti.

Czechoslovakia also used TW39 like Germany. First with mainly RFT T51 machines and later with Siemens T100 licenced model.

The UK used a double current +/- 80 volts system so far I know. But I am sure Sam or Larry can tell more about that.

Form Australia I know that there also was a double current network in use. First starting manually switched and later changed to automatical switching dial up network.
Early machines were Creed 7b, later mainly Siemens T100 (M100) and then in the electronic age all kinds of Sagem from France.
But here also Larry can tell more...

BTW: A couple of years we started an automatical dial up network over telephone lines, we call TelexPhone. Our PC board (using a PIC) emulates the functionality of a TW39 exchange with it's signalling protocol. So you can more or less easily ;-) connect an old TW39/55 machine with its control unit and chat over telephone lines. We are a growing community and have much chatting and telexing over phone like in real in the old days.

rgds,
Henning DF3OE +++

www.teleprinter.net


---------- Original Message ----------------------------------
From: Sam Hallas <s.hallas at ntlworld.com>
Date:  Thu, 25 Jan 2007 22:08:53 +0000

>WA3FRP at aol.com wrote:
>>  
>> Hi!   I'm a retired  Western Union guy! etc
>
>Fascinating stuff from all the correspondents on this thread. I was 
>hoping that some of our experts from 'the rest of the world' would chip 
>in with details about what machines were used in Europe/ Australasia etc 
>on the 50 Baud, ITA2 telex network. Henning? Larry?
>
>Cheers,
>Sam (only a telephone engineer, never actively involved with the telex 
>network)
>
>
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