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