Rather than have the grooves only 1/4" deep in the radial spoke structure, I would deepen them to 1/2" or 3/4", allowing me to stack one conductor immediately on top of the other in direct contact with each other. The ends of the two parallel spiral tubes would be pressed together with light pressure from a cap-bar affixed onto the top of each spoke. Thus each of the five spokes ensures contact between the two spirals, but the start and end of the winding would be soldered together as well. Tapping would be the same as I've done previously, only I would use a split/tap that attaches to both the top and bottom conductor, at the same location in the winding. Being this was a hybrid of a tube and a ribbon (aspect ratio perhaps resembling a ribbon, but with well-rounded top/bottom edges), I wondered what the final outcome would be versus either a single tube, or a single traditional ribbon with thin and perhaps sharp edges.
Terry
On Monday, May 4, 2020, 04:42:31 PM CDT, Gary Lau <glau1024@xxxxxxxxx> wrote:
I believe I recall that with ribbon conductors, the current flow is
concentrated at the top and bottom edges and the copper in the middle is
mostly wasted. Some time ago I performed an experiment to compare primary
losses for various primary coil geometries, including ribbon, tubing, Litz,
and various other things. The copper ribbon was unrerkable in terms of
losses. See http://www.laushaus.com/tesla/primary_resistance.htm
That aside, I can't imagine how to keep 3 spirals of tubing aligned with
each other and tapping it.
Regards, Gary Lau
MA, USA
On Mon, May 4, 2020 at 5:25 PM Terry Oxandale <toxandale@xxxxxxxxxxxxx>
wrote:
>
> I'm rebuiding my primary (and other parts), with the intent of using a
> larger diameter tube (going from 1/4" to 3/8"). It would be very convenient
> to use the same primary footprint I'm currently using, and feel I could do
> this with the larger tubing, but would like to have some margin of unused
> turns for flexibility in components.
> So my question to the group relates to primary turn stacking. I'm
> considering stacking 2 to 3 layers of 1/4" tubing (to resemble a ribbon
> versus a single, larger diameter, round conductor) into each slot of the
> structure. Looking at increase power, efficiency, etc, and think this may
> be a way to keep the radius constrained, while improving the performance.
> Thoughts and experiences of this from the group?
> Terry
>
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