[GreenKeys] Question regarding TWX and Dial TWX...

[larryradio at att.net]

Hi Jerry,

I can connect them with a simple 12 VDC in series with their cords to the 
42A block.  Reversing polarity can turn them on or off.  The rotary dials 
pulse that 12  VDC loop.  There is a box of relays with German markings.  I 
don't have the prints on these boxes so I carefully leave them alone :>)

The boxes have several lighted buttons, 2 or 3....not near them at this 
time...however, when a button lights, pushing it can shut down the 
machines....probably does a momentary reversal.  The Model 15's also have a 
"Here Is" button above the KB but, the relevant "machinery" is missing from 
the KB assembly.  Clearly, it was there at one time.

Thanks to all for all the info.

lar
----- Original Message ----- 
From: <gfmurphy at earthlink.net>
To: "Larry Tighe" <larryradio at att.net>; "Greenkeys" 
<greenkeys at mailman.qth.net>
Sent: Friday, April 23, 2010 7:47 PM
Subject: Re: [GreenKeys] Question regarding TWX and Dial TWX...


>
> Hi Larry:
>
> Your RCA machines would have been used to provide Telex service on the
> RCA network.  They could not be used for domestic service but could be
> used to access machines in other countries.  The dial and the telephone
> line connection did not necessarily indicate that it was hooked to a
> voice frequency system such as TWX.  Unless there is a modem , it was
> most likely hooked to a neutral circuit.  As others have pointed out,
> the IRCs (International Record Carriers) were allowed to provide telex
> machines in the "Gateway cities."  Since distances were usually not too
> great, a neutral circuit was usually adequate.  If I remember correctly,
> the gateway cities were: New York, Washington, Miami, New Orleans and San
> Francisco. (Also, whenever the local telco dropped off an outlet for a
> telex or TWX machine, it was always terminated in a 42A connecting block
> and the easiest way to connect to one of those was a telephone cord.)
>
> I remember the telegraph office at Standard Oil in San Francisco:  They
> had machines from RCA Global Communications, ITT World Communications,
> Western Union International, Western Union Domestic and Bell System TWX.
> (There may have been some other carriers that I don't remember.)  There
> were multiple circuits from each carrier.  In addition, they had a private
> line tty circuit to their telegraph office in the UK.  They also had an
> extensive private Teletype network that moved messages to and from their
> facilities in the SF Bay Area.  No Model 32 or 33 equipment there; It was
> all 28 or 35 machines.
>
> Regarding dialing of Telex or TWX numbers:  The use of a dial to establish
> a connection seems obvious. That was called Type A dialing.  There was 
> also
> Type B dialing where the number keys on the keyboard (and the + character)
> were used to establish the connection.  I remember that ITT World used 
> Type
> B dialing.
>
> According to the FCC, domestic Telex/TWX was anything in North America.
> Anywhere else was an international call and had to go through an IRC.
>
> The normal connection in international Telex was a 2 way set-up where the
> operators could type back and forth.  In reality, most Telex messages were
> of a one way nature (like email).  Where there were big time differences,
> all that was really needed was a store and forward setup.  Operators could
> send a message to the store-and-forward computer and they would get a
> notification back when the message was delivered.  This was cheaper and it
> provided a more predictable traffic flow on long haul facilities.  Later
> refinements allowed IRC customers to contact the store-and-forward 
> computer via
> dial-up terminals (remember computer time share terminals?) to send or 
> pick
> up messages from locations outside of gateway cities.  When dial-up 
> terminals
> were available, you did not need a Telex machine or line.  All that you 
> had
> to have was a Telex number from one of the IRCs and a password.  Protocol 
> and
> speed conversion from the dial-up terminals were provided by the store and
> forward computer.  But, in the end, FAX machines and email did in the 
> Telex
> system.
>
> A circuit for interfacing a 5 level machine to a Telex line is described 
> in
> in the M32 manual (309B - Vol 1).  For those of you who have Telex 
> machines,
> it describes what is happening on the line.  You can build the "office 
> end"
> of the circuit and get your machine to turn on and off by reversing the 
> line
> polarity.
>
> Regards, Jerry Murphy
>
>
>
>
> -----Original Message-----
>>From: Larry Tighe <larryradio at att.net>
>>Sent: Apr 23, 2010 12:12 PM
>>To: Jim Haynes <jhhaynes at earthlink.net>
>>Cc: greenkeys at mailman.qth.net, Bryan Brodie <b.brodie at vaporland.com>
>>Subject: Re: [GreenKeys] Question regarding TWX and Dial TWX...
>>
>>Thanks Jim and Don,
>>
>>BUT, where do my RCA Global Model 15's fit into all this?  They have 
>>rotary
>>dials on the accompanying box and a telephone line connection...2 wire.
>>
>>Did RCA Global have the international business? Or, did they compete with
>>W.U.?  I think my RCA Model 15's deserve recognition in this discussion 
>>LOL
>>
>>lar
>
>
>
>