[GreenKeys] Using Telex Machines Made E-Z....

[George B. Hutchison]

GreenKeyers - - -

Using a Teletype Corporation equipped telex machine on RTTY is relatively
easy.

You need a loop supply with a current limiting resistor (2K or so
wirewound pot) a double-pole double-throw switch, and the telex machine.

Connect the DPDT switch in the standard manner for reversing polarity.
Feed the loop supply (Such as one would find in a 28 LESU) through the pot
to the center terminals of the switch.

Wire the reversing terminals of the switch to the telex machine input
cable/terminals.

If you plug the telex machine into 110 VAC, with the loop supply
de-energized, it will run open.  Some folks tweek the dial on the telex a
bit to get the machine to lock up, but this is not necessary.

Energize the loop supply. Depending upon the position of the DPDT Switch,
the machine will either stop running open, remain on and be ready to type
uponst, or will shutdown and the motor will stop. Flipping the switch will
result in the opposite condition to occur. With the machine energized and
the loop locked, set the loop current for 60 ma.

When the machine is on and ready to type, it will key the loop that is
coming from the loop supply. From there it is easy to use it to key
another machine, a transmitter, or what have you.

When the machine is in the off condition, motor shutdown, etc,  depressing
the "LOCAL" button on the telex will cause it to come to life so you can
type locally.

I have an ST-6 that I removed the 110VAC  that goes through the motor
control relay, and set it up with the reversing arrangement as described.
Most ST-6 motor control relays were DPDT. The loop current from the ST-6
goes through the motor control/now reversing relay, so when the ST-6 says
turn on the motor, the loop current flips polarity and turns on the telex
machine. Such a deal.

Thought some of you might like this bit of info.

73,

George, W7KSJ