RE: VTTC provisional results

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "James by way of Terry Fritz <twftesla-at-uswest-dot-net>" <mustang3-at-home-dot-com>

Hi Herwig and all,
   To attach the primary winding, I glued a small piece of pexi(using epoxy)
to my pvc former at both ends of the winding. I just used hot glue and tape
to hold the tickle(grid) coil in place. It was only #20 magnet wire(left
over from my SG Tesla coil). I had already tried using screws through the
former. Even with an inner layer of plastic, I got arcs from the last
primary turn to the secondary.
	The specs on my VTTC are:
	two 500 w. triodes in parallel
	MOT xmfr with 1/2 voltage doubler
	6" dia. X 24(winding) #27 wire
	25 turn primary #10 THHN wire wound at a 60 deg angle
	5 Nf 10KV mica cap
	18 turn tickle winding #20 magnet wire
	3.6K ohm grid leak with a 3 Nf cap.
  I get arcs of 16 to 18 inches. At 140 volts into the plate xmfr, it draws
25 amps.
  God, I love this stuff.
									later,
									  James


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Friday, March 16, 2001 9:08 AM
To: tesla-at-pupman-dot-com
Subject: RE: VTTC provisional results


Original poster: "Herwig Roscher by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <herwig.roscher-at-gmx.de>


James wrote:

> The arc would smoke the primary and short it (large carbon
> track).

James,

Sorry to read that you faced the same problem.

> I rewound the primary as a funnel. It will be a pain to do 65 turns.
- Before taking this trouble I would like to make an other approach:
I am planning on substituting the PVC insulated house wire by
magnet wire of the same copper cross section. This would half the
height of the coil and reduce the voltage difference between the
uppermost turn of the primary coil and the secondary coil (as the
voltage of the latter increases with height).

As I suspect that the sharp edge of the flush screw, I used to fix
the wire, contributed to the effect, I shall try to find a better
solution. How did you solve this problem?

As PP has got a smaller dielectric factor than PVC it should create
smaller rf surface currents which are the reason for these carbon
tracks and flashovers IMO. Unfortunately I could not find a 8" PP or
PE form (should have thin walls!) up to now.

Regards,

Herwig