[GreenKeys] Loop Supplies

Tom Hunter tomhenryhunter at gmail.com
Sat Jan 1 20:25:36 EST 2022


Loop supplies are so simple, I build my own. This one is my pride and joy -
a dual loop supply. It uses a single transformer but everything else is
separate - two rectifier diodes, two filter capacitors, two 2K dropping
resistors, two wirewound pots and two meters. I don't have any interaction
between the two sides.

I don't have a photo of the back but the electrical box that is just
visible has the transformer mounted on it, The primary AC wiring including
the fuse is inside. Also inside are the rectifiers, the filter caps and the
2K resistors.. Then the positive wires come out to the pots, the meters, a
barrier strip and the two sets of jacks.

I did not bother with a power switch because it stays on all the time.

The ground (negative) wires connect to a 4-terminal barrier strip. The
positive from the pots connect through the meters to the rightmost of the
jacks then from the leftmost jack to the barrier strip. Of course they are
all normalling jacks and are available if l need to plug in a teletype, or
anything else.

I make my external connections to the barrier strip.

The jacks are two-circuit and each is insulated from the panel with a
shoulder washer in back and a flat washer in front.

The left side powers my "Test" loop. A military Dovetron in the rack with
my RTTY repeater operates a polar relay on the wall which is connected to a
polar output of the Dovetron. The marking contact of the polar relay is in
a loop powered by the right side of the loop supply.


Tom N3CRK
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