Tension and Field Coils.

Much has been said lately about the difference between low voltage and high voltage field coils.  The first Lowther prototypes were done at 200V for the sole purpose of the cool glow of mercury in the supply. Alas I never got around to building a proper mercury supply for them before the revisions and subsequent production which ruled out the possibility of the HV supply for safety reasons.  We did get to do the mercury LV supply though.

The question of low voltage high current vs. high voltage low current is a tough one to investigate in an apples to apple way but the first step was to rework a pair with 4 identical windings which can be placed in series or parallel to compare 15V @ 2A to 60V @ 0.5A.  To get the wire to do the four parallel runs I needed to de-spool 4 rolls from a 100 pound roll of wire.  I did all of the calculations and added 10% even though things were getting me a bit nervous at the end, It all worked out.

Here they are all buttoned up and ready to go to the test subjects who will do the comparisons with 8" baskets in160hz front horns and with 5" baskets in a pair of full range back loaded horns.  Along with the field coil,  we are also sending a pair of alnico and Neo 5" drivers so we can get the report on those differences too.