[GreenKeys] How long can a local loop be?

[Duncan Brown]

Teletypewriters were originally designed to operate in DC loops with a 
ground return.

The specification for the Signal Corp's TT-4/PGC-1 was 25 miles at 60 
wpm and 15 miles at 100 wpm (depending on ground conditions). This was 
with 60 ma loop and ground return.  This was machine to machine. They 
did not use polar relays except in repeaters to extend the range.

have fun,

Duncan
K2OEQ

On 6/13/2019 17:19, Joe Herdler via GreenKeys wrote:
> Hi all,
>
> How long can a local loop be? Would a pair of TTYs work at a mile 
> apart with twisted pair wire? Or would one need to start thinking 
> about using a polar relay and dual current for mark and space? What 
> would the circuit look like? At that distance (mile +), does one need 
> to think about open wire and insulators?
>
> Thank you again!
>
> Best,
>
> Joe
>
> Consciousness affects the medium. Think happy, be happy, and happiness 
> will follow you.
>
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