[GreenKeys] New RTTY Handbook TU's

[Jeffrey Angus]

On 4/5/21 11:22 PM, Harold Hallikainen wrote:
> When I was in high school, I remember one of my model 15s having a polar
> relay in the back. There was also a TU that used a polar relay to make the
> mark/space decision. In general, I did not find much use for the polar
> relay.
Historically, Hams have a tendency to make things more complicated
than necessary.
> I guess they were used on telco loops. Is there an advantage to polar
> signals versus on/off on a telco loop? I guess there might be an advantage
> in that the receiver is driven to mark or space instead of just being
> driven to mark with a spring pulling the armature to space. It would be
> interesting to have a selector magnet with a permanent magnet where
> current in one direction would pull the armature to the coil, and current
> in the other direction would push it away.
Absolutely unnecessary, teletype machines, by themselves work just fine
with on/off keying.

Polar keying is for long distance loops.

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