Original poster: "Kelly & Phillipa Williams by way of Terry Fritz <twftesla-at-uswest-dot-net>" <kellyw-at-ihug.co.nz>
Hi All,
A few months ago Malcolm Watts showed me his coil. The secondary was
spacewound, and at the top, the secondary wire was joined to a piece of 1/4
inch copper tube, which made about two fairly widely spaced turns around the
top of the PVC pipe before joining onto the toroid. The purpose of this was
to let corona come off the two last turns of tube instead of from the last
turns of thin secondary wire, possibly damaging it.
I want to do the same thing, but on my secondary, the turns end about 0.23
inches from the top of the tube (less than a finger's width)
and I thought I'd mount the first turn of tubing on the top edge of the
tube, and then do another spiral turn upward just in the air above the tube
with no former. The tube I have is ridgid enough to take a knock and keep
it's spiral shape, and I'd mount the toroid just above the tube on a disk
supported by a very small diameter PVC pipe inside the large PVC former, and
connect the toroid to the tube.
0000000
000000000 - independently supported toroid
0000000
---___ - unsupported upward spiral of tube connected to toroid
---___ - start of unspported upward spiral of tube
|=====| top of PVC
| |
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| |
| |
| |
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|_____|
1) Is this a sensible idea? One problem I can see is the secondary arcing
internally
from the tube down into the secondary former, through an imperfection in the
wall, and damaging a winding. I could cap the secondary below the start of
the tube spiral, but would this stop the internal arcing?
2) Or, should I just put an incomplete ring of tube around the top of the
PVC, and then connect one end to the top of the secondary and one end to the
toroid?
3) Do I need this at all if the toroid overhangs the windings?
Thank you very much!
Alan Williams