[GreenKeys] 255A Polar Relay Wiring

[Tom Hunter]

A while back someone asked me  how I wired a polar relay to my military
Dovetron. I finally put it together.
I used coax with a BNC on the Dovetron +/- 12V end and wired the relay end
to a solder terminal strip. I used stranded hookup wire to connect to the
relay. Since I did not have a socket and did not want to solder to the
plug, I pulled wrap-around pins from an old octal tube socket, squeezed
them tighter with pliers and pushed them on the

[image: My 255A Relay.jpg]
The shield of the coax is connected to pin 2 of the relay, the center
conductor to to pin 6. Pins 3 and 8 are jumpered
to put the two windings in series aiding. The marking contact is taken from
pins 1 and 4, In my system this goes to a  plug to patch it in to any loop
with a loop supply. The relay is mounted on an aluminum plate to fit  a 4
inch square electrical box since the relay is mounted sideways, I made sure
the contacts were horizontal so they would not be biased by gravity. It
worked the first time.

I am attaching a drawing of the 255A from the New RTTY Handbook, page 71
and a photo of the installed relay patched into one of my loops.


Tom   N3CRK
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