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Re: Question on Primary Lead Heating

Original poster: "resonance" <resonance@xxxxxxxxxxxx>

Make a clip by drilling a .005" undersize hole in a piece of 1/2 inch thick brass block. Then saw the block in half. Use a 10-32 NF brass fastener on each end to clamp down on the primary. Another end hole is drilled axially into the brass block which allows attached of a copper battery lug to a 4AWG piece of welding cable. This system we have used in coils from 6 kVA thru 100 kVA with no heating problems. Of course, larger kVA sizes require larger brass blocks.

Dr. Resonance

Hello Tesla List,
I have been conversing with Bart Anderson about some quirks in the ways my DF-DRSSTC works vs computer models. As an aside discussion I was mentioning that my lead to the primary tap on my coil gets hot. Bart was giving me some pointers on a primary tap connecter he made which provides a good connection to the primary coil. (you can see it in some of the photos on Bart's website).

I was mentioning that my primary connection wire got hot at the point where the lead screws into the battery clip I was using for a connector. It also heats in the first inch or so down from this connection. When I was first trying to tune the coil, the lead got hot enough to melt the insulation on the #12 wire after only a 10-20 sec run. After finally figuring out where this coil wanted to tune (best tune point) the lead still gets pretty warm (hot to touch).

The thing I found interesting was that the primary coil leads feed into a circuit board where they are fed by hook up wire (~#22). The primary is about 5 turns of #6 solid copper. The thing that is puzzling is that the #22 wires feeding the primary do not seem to get too hot. Also the heat sinks on the IGBTs don't get uncomfortably hot.

My thinking is that the unit is acting like an induction heater, and that some point along the primary lead is a node where current is high. The hook up wire lengths are fairly short compared to the primary tap lead.

Maybe some others on the list have seen this and can shed light on it.
Jim Zimmerschied