[GreenKeys] What type of wire for loop?

[Harold Hallikainen]

> Hi All (again)
> What type of wire would be best for field use to connect Teletypes
> together over several miles?
>
> Would field telephone wire work? I am assuming that the wire should be
> twisted.
>
> I am thinking as if I would someday have to use these wonderful white
> elephants in an actual situation.
>
>
> Thank you very much, (again)
> Best,
> Joe H

Back when I did this in high school, I used untwisted surplus military
field telephone wire. I bought a roll at one of the Oakland CA airport
surplus stores and untwisted it to get more wire. This ran through trees
in the neighborhood a couple miles. We had a model 16 at each end and a
loop power supply at each end. We added some slow release motor start
relays. When either end brought up loop current, the motors would start
and continue running until a long interruption in the loop current. This
system used ground as one side of the loop.

However, a few miles of twisted pair field telephone wire seems like it
would do fine. The 45 baud (a frequency of about 23 Hz) can easily go for
a long ways on a twisted pair (about the same as telephone ringing
voltage). It might be nice to use a 20 mA current loop (series holding
magnets). The wire resistance is likely to be small compared to the
current limit resistor in the loop supply.

Harold
http://w6iwi.org



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