RE: [TCML] New 833C VTTC - poor performance

["Lau, Gary" <Gary.Lau@xxxxxx>]

The TDK spec for the UHV series does not specifically state for RF use, but says:
"When the capacitor is used for high-speed pulses such as with a
laser, make sure that the impressed voltage (peak-to-peak voltage)
is within the capacitor's rated specifications."

The dissipation factor is spec'ed as 0.2% max.  Not sure how that compares with polypropylene units.

Regards, Gary Lau
MA, USA



> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of DC Cox
> Sent: Friday, August 01, 2008 2:24 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] New 833C VTTC - poor performance
>
> check to be sure the TDK tank cap is rated for RF current and is not a DC
> filter type cap.
>
> you may also have to experiment with the position of the grid leak coil ---
> sometimes it is necessary to have it 6-10" up the sec coil for best results.
>
> measure your grid drive current to be sure you are driving the 833 properly.
>
> Dr. Resonance
>
>
>
>
> On Fri, Aug 1, 2008 at 12:05 PM, Kris Grillo
> <kristianisawesome@xxxxxxxxx>wrote:
>
> > I just finished my first VTTC. It's a single 833C closely following Steve
> > Ward's single 833A schematic. The specs:
> > Secondary - 3.5" x 17" x #26
> > Topload - 2" x 7.5" toroid, about .25" above the top turn.
> > Primary - 29 turns #12 THHN on a 6.25" green pipe. Bottom turn level with
> > secondary bottom turn.
> > Filament supply - rewound mot, 10V even (does get warm).
> > Plate supply - very large (physically) old mot, shunts removed, voltage
> > doubler 2.05uf, mo diode, 2nf10kv ceramic disk
> > Tank cap - 2nf 40kV TDK UHV doorknob
> > Plate filter - 12 turns #12 on 50ohm 20W
> > Feedback coil - 20 turns #26
> > Grid leak - 4k 125w variable, 2nf 40kV TDK UHV doorknob
> > Everything is wired with #12 wire. All connections are tight.
> > No staccato yet
> >
> > For some reason, I can't get past 6" - 8" arks and about 75 volts in from
> > the variac without the plate starting to glow orange. I've tried 24 - 20
> > turns on the feedback, 20 - 31 turns on the primary, varying the grid leak
> > resistance between 1K - 4K, varying the feedback coil from .5" above the
> > primary all the way to 8" above. I tried going with 1.75uf and 2uf on the
> > votage doubler. I tried a 4" pvc secondary with 19.75" of #26. I know the
> > 833C can do better than 8" arcs. It's a brand new Taylor from RF parts, by
> > the way.
> >
> > I'm out of ideas. Anyone have any suggestions?
> >
> > Thanks
> > Kris
> >
> >
> >
> >
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