Re: My single 833A vttc -- first light!

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>

Brett - Wow!  You've made some real quick progress!
I'll be really interested to hear how those Yish caps
go.  Do they get pretty warm?  The price is certainly
right; I was planning on using them for my VTTC if a
suitable mica doesn't turn up by the time I've got all
the rest of my parts.

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: Brett Miller <brmtesla2@xxxxxxxxx>
>
> All,
>
> My single 833A vttc had first light tonight..at
> least,
> first light with full power (due to the voltage
> doubler being installed).
>
> Performance was amazing, it easily started eating
> its
> own breakout point, which was a heavy (one of the
> larger ones) paperclip, straightened out and wrapped
> around a bolt which sits atop my John Freau toroid.
> You can see it happening in this picture:
>
>
http://hot-streamer.com/brett/vttc/single_833_noshunts_with_doubler.jpg
>
> In that picture the coil is generating about 8"
> swordlike streamers into free air, however, I have
> video which shows some reach out to 14-15".  I could
> possibly achieve an even greater distance once I set
> up a grounded target for the discharge.  I may need
> to
> mount a tungsten breakout point atop that toroid as
> well.  Something interesting I noticed, was that
> after
> the paperclip point melting into a sphere of molten
> metal the swordlike streamers began to appear in
> opposition and extend in various directions, with
> the
> curvature of the small metal sphere as the radiant.
>
> I have spent a lot of time tuning in the raw ac
> mode,
> and I arrived at a combination of primary tap, grid
> leak resistance, and feedback coil height, that
> seems
> to provide optimum output at least current demand
> from
> the mains.  However, as John F. and others warned
> me,
> tuning a vttc is quite a challenge.....John, you
> sure
> said a mouthful there.
>
> Specs as of tonight:
> -----------------------------------
>
> Single used 833A...label rubbed off (possibly RCA?)
>
> Plate transformer:  Large MOT with shunts removed
>
> Voltage Doubler:  3 oven caps and one oven diode
>
> Filament supply:  MOT with secondary cut off and
> rewound with AWG12....provides 10.7v at around 9.8+A
> at the filament pins
>
> Secondary:  19" winding length on 3.5" PVC former
>
> Primary:  28 turns AWG12 THHN, currently tapped at
> turn 21
>
> Feedback:  25 turns AWG23 magnet wire on slidable
> form.
> (coil did not oscillate at first...swapping these
> wires *did* promote oscillation in my coil)
> Currently
> the plate seems happier with the feedback coil about
> 2
> inches above the top of the primary.
>
> Grid leak system:  2 in series 3K Ohm 50W Ohmite
> power
> resistors in parallel with a single Yish 1.1nf 50kv
> doorknob cap
>
> Tank Cap:  2 Yish 1.1nf 50kv doorknob caps in
> parallel
>
> Topload:  1 John Freau 1.75" x 6" spun aluminum
> toroid
>
>
>
> Well, those are the specs I can think of...all
> grounds
> tied to a common point and connected to the same rf
> ground that gave great results in my 45" spark 12/60
> disruptive coil.
>
> I think I may have stated (at least to a few people)
> that I wasn't interested in getting competitive
> spark
> lengths here...but I think with some fine tuning
> (and
> staccato of course) I will be up in the 20"+ range.
> That would be extremely favorable.
>
> Cheers,
>
> -Brett
>
>
>
>
>
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