[GreenKeys] M33

Sat Apr 10 10:30:50 EDT 2021

Paul,

So AT&T converted between ASCII and 5-Bit and a TWX 33 is an ASCII machine based on the 33 with different electronics?

Sounds like it might be hard to use on I-Telex which is a 5-bit system?

Dave

From: Paul Heller <paul0926 at comcast.net> 
Sent: 10 April 2021 14:22
To: dave.g4ugm at gmail.com
Cc: GREENKEYS BULLETIN BOARD <greenkeys at mailman.qth.net>
Subject: Re: [GreenKeys] M33

Telex machines are five bit machines and operate at 66 WPM (50 baud). There were a number of manufacturers: Siemens, Lorenz, Teletype just to name a few. Teletype telex machines are basically a model 32 and usually have a rotary dial for calling other telex machines.  Hams would buy Telex machines and change the gears to the operated at 60 WPM (45 baud) so they could be used for RTTY.

TWX was an alternative to Telex offered by AT&T. It was available in five bit, 50 baud service or 8 bit 110 baud service. The AT&T service network could convert between the two. The 110 baud TWX machines were based on a Teletype model 33. 

If you have a  3 row key keyboard and a rotary dial calling unit it is very likely a telex machine, but could be a TWX machine. If you have a four row keyboard and a push button calling unit it is very likely a TWX machine. I say “usually” because there were exceptions. 

I believe a TWX Model 33 teletype is not easily converted to a current loop Teletype, but it can be done if you find the right parts. Wayne knows. I have heard that a TWX 33 can be hooked to RS-232 ASCII.

Paul
W2TTY

ITTY:                    HTTP://INTERNET-TTY.NET:8000/ITTY
AUTOSTART: HTTP://INTERNET-TTY.NET:8030/AUTOSTART
EUROPE:           HTTP://INTERNET-TTY.NET:8040/EUROPE

On Apr 10, 2021, at 1:51 AM, dave.g4ugm at gmail.com <mailto:dave.g4ugm at gmail.com>  wrote:

Chuck,

Isn’t a 33 an ASCII terminal? Do you mean a 33 or a 32?

Dave

G4UGM

From: greenkeys-bounces at mailman.qth.net <mailto:greenkeys-bounces at mailman.qth.net>  <greenkeys-bounces at mailman.qth.net <mailto:greenkeys-bounces at mailman.qth.net> > On Behalf Of Yahoo
Sent: 10 April 2021 03:39
To: GREENKEYS BULLETIN BOARD <greenkeys at mailman.qth.net <mailto:greenkeys at mailman.qth.net> >
Subject: [GreenKeys] M33

Well I found a M33 TWX machine at an estate sale today and wondered what I should look for when I get it home?

I will try and set it up for I-Telex as it has the Dial on the right side and something in the Base/Stand that I have not looked at yet

What next other then looking at Nick's site for manuals?

Chuck

N7UVZ

Carson City

Nevada

.

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