VTTC Questions

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

Original poster: "Andy Cleary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <cleara-at-twcny.rr-dot-com>

Hello All,

	I have just recently finished on my first VTTC, and I must say it was
a lot of fun!  Unfortunately, the thing hardly works, so naturally
I've got a few questions - (skip past the specs to see them)

First, the important coil specs:

1 Tube: 4-125A
Input: 3KVAC MOT, NO voltage doubler
RF Bypass cap: .85uf 2500 vac microwave capacitor

Tank Cap: .002 6KV RF Transmitting Cap
Primary Coil: 28 Turns Solid PVC Coated 14AWG Wire wound on a 6.5" OD
PVC Form, top 10 turns tapped every 5"
Plate Protection: 50 Ohm resistor wound w/ 10 turns 14AWG PVC Coated
wire

Secondary Coil: 3.5" OD PVC Wound 11.125" with 28 AWG Magnet Wire 	=
538Khz no load
Topload: .6" Radius metal  ball, raised 2" from top of coil 		= 470
Khz
	or 3" dt (tubing) 8" dtc (diameter at tubing center) torus		= 302 Khz

Grid coil: 20 turns of 22 AWG magnet wire, .75" above primary on same
form
Grid Leak resistor: 0-5k variable pot, 20W
Grid Leak capacitor: 2.64 nf or 1.32 nf (both sizes tried)

The filament is taken care of with a commercial 5v filament
transformer on variac.

The schematic that I closely followed is at:
http://207.189.173.115/webdoc2.htg/803_schem.htm



Now for the questions:
Currently, my setup using any and all combinations of grid-leak
capacitance, grid-leak resistance, primary taps, and toploads gives at
maximum 1" Discharges (whereas the tube should be capable of at least
10").

Is there something fundamentally flawed with my component selection?

Right now, changing the grid-leak resistance and/or capacitance has no
effect on the output - what should it be doing?

Most of my calculations were done using Wintesla, which is primarily
for disruptive coils - should the calculations for primary tapping,
etc. still hold for VTTCs?  If not, what program will work, or what
calculations are different?

What effect would primary-secondary coupling have on performance?
Height of topload?

I have tried 2 tubes, neither worked any better.  They are both used,
could something be wrong with them?

Any other suggestions?


Thanks for reading, and thank you in advance for any help!

-Andy C.
--------------------
Andy Cleary - KC2GVE
RPI Electronics Club President
AJAX Electronics
cleara-at-rpi.edu
Geek# 1010
www.rpi.edu/~cleara/
-------------------