[GreenKeys] Teletype (telephone) Local Loops

[Jeffrey Angus]

I always enjoy the "local loop" discussions.
Especially the  technical aspects of from a Central Office point of
view.

However, this needs to be said.
We, as a group,with maybe one or two exceptions, do not have
"local loops" the length of which the central offices had to
contend with. At the most 50-100 feet.
And, again, with a few exceptions, most of us don't have to
supply power to more than a handful of machines.
Most of us have the loop resistor at the power supply so the
likelihood of damage from shorted cables is minimized.
Lastly, while I was fascinated with polar relays, and I still have
a few, I've never understood why anyone would want to go
through the effort to overly complicate a local loop with one.

As an example, the length of my local loop with the i-Telex
equipment is roughly 10'. At the extreme end of things, the
HAL ST-8000A sits back in the far end of the shop about
75' from my machine.

And, if I were basically insane, and wanted to pay AT&T for
the service, I could order a dry pair from the shop to the
house, but even that would be less than a mile, even
including looping through the local AT&T central office.

One last remark about polar relays. The open circuit voltage
was the same. 120-130 vdc. Not +/- 48 vdc. But rather +/-
30 mA line current instead of 60 ma make/break line current.



-- 
"I am a river to my people."
Jeff-1.0
WA6FWI
www.foxsmercantile.com