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Re: [TCML] VTTC grig coil help
In outlining your plans for an 833 VTTC, you described the grid feedback
"It will be wound on a small piece of split thin-wall PVC so it can slide up
and down on the acrylic form."
Can you describe how this will work?
It would seem that even if you split the bare PVC coilform, once the wire
was wound on the coilform it would no longer be able to "expand" and slide
on the secondary, and the ability adjust its position on the secondary would
Or am I misinterpreting your design?
----- Original Message -----
From: "Jim Mora" <wavetuner@xxxxxxxxx>
To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx>
Sent: Friday, July 03, 2009 4:00 PM
Subject: [TCML] VTTC grig coil help
Hello Esteemed Fellow Coilers,
I am engaged in the long haul of building a 4x 833a coil. I have been
collecting stuff for a few years.one of my prizes are original Johnson
screw sockets in NOS condition along with Johnson heat sinks - nice
The secondary is 6" acrylic. The primary is a 8" acrylic form. Initially
will be running CW for tuning and power tests ( 4 used tubes cam be
alright before I turn up the new 833C's), I'll run them near red to test
cooling effectiveness. Duty cycle will be solely accomplished by the
staccato circuit. The secondary will be wound 24" with #21awg and will
a small aluminum plate on top to keep the frequency up very near 350Khz
(Fo=~348Khz) which some say is a magic number for sword like discharge.
the staccato duty cycle cancel the CW hiss-like high power and cause the
to behave in the aforementioned sword like discharges? I do want to
this too in CW mode (no antenna ;-^) By the way, what is the best way to
that sans a big modulation transformer, since we are controlling
with a SCR or? which leads to another problem- in CW filtered mode - how
I turn off the SCR, power off B+?
I am trying to get my head around the feedback grid coil geometry. It will
be wound on a small piece of split thin-wall PVC so it can slide up and
on the acrylic form. The primary is to be 3/16 soft tubing, (.1875")
by same a little over 20 turns - math looks pretty good so far. I know I
have to raise the secondary a couple of inches from the base to get K in
2X range (pretty tight but recommended in my readings). Cap = .003 mica in
series parallel. I may be wrong, but I don't think the grid coil coupling
the secondary should matter? It seems to me the field from the primary
swamp the secondary's influence on the feedback coil. So here's the
for our VTTC experienced coilers: How many turns of what size wire should
this critical grid feedback component have and should it have layers as my
former is 11"? I am fat on many wire types, magnet and PVC coated in
multiple gauges. Please keep in mind that I have a very stiff PS (big iron
and filter) that will deliver 2KW real power no sweat at full duty.
"The multi-tap big iron came from Tabasco Jack in San Diego, Kudo's Jack!
lurks here I think. It will be on its own casters separate from the coil
is a heavy two man/women lift! 12 taps: 3KV- 14,400.
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