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RE: [TCML] VTTC grid coil help
Hello,
Yes, I was afraid someone would interrupt that statement that way. The split
coil will be ON the primary and may even have a sheet of paper under it
which seems like a good idea as I type this as that will make coating a
cinch! The grid coil will only be 20 turns or so of #18AWG heavy insulated
magnet wire on the slider and it will be wound first. And, yes, I have been
there done that ;-) Thanks for the heads up though :-) BTW, the PVC inner
diameter = the acrylic outer diameter. I would not have been happy with
myself to make that mistake again ;-))
Regards,
Jim Mora
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Quarkster
Sent: Saturday, July 04, 2009 7:51 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] VTTC grig coil help
Jim -
In outlining your plans for an 833 VTTC, you described the grid feedback
coil as:
"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
be lost.
Or am I misinterpreting your design?
Regards,
Herr Zapp
----- 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
> thumb
> screw sockets in NOS condition along with Johnson heat sinks - nice
> patina.
> The secondary is 6" acrylic. The primary is a 8" acrylic form. Initially
> it
> will be running CW for tuning and power tests ( 4 used tubes cam be
> toasted
> alright before I turn up the new 833C's), I'll run them near red to test
> my
> cooling effectiveness. Duty cycle will be solely accomplished by the
> staccato circuit. The secondary will be wound 24" with #21awg and will
> have
> 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.
> Will
> the staccato duty cycle cancel the CW hiss-like high power and cause the
> CW
> to behave in the aforementioned sword like discharges? I do want to
> modulate
> this too in CW mode (no antenna ;-^) By the way, what is the best way to
> do
> that sans a big modulation transformer, since we are controlling
> conduction
> with a SCR or? which leads to another problem- in CW filtered mode - how
> do
> 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
> down
> on the acrylic form. The primary is to be 3/16 soft tubing, (.1875")
> spaced
> 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
> the
> 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
> to
> the secondary should matter? It seems to me the field from the primary
> will
> swamp the secondary's influence on the feedback coil. So here's the
> question
> 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.
>
>
>
> Thanks much,
>
> Jim Mora
>
>
>
> "The multi-tap big iron came from Tabasco Jack in San Diego, Kudo's Jack!
> He
> lurks here I think. It will be on its own casters separate from the coil
> and
> is a heavy two man/women lift! 12 taps: 3KV- 14,400.
>
>
>
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
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