Re: Antonio - variable vacuum capacitor if you want

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Antonio,

At 11:42 PM 12/26/2002 -0200, you wrote:
>Tesla list wrote:
>
> > Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> >
> > Hi Antonio,
> >
> > I tried mailing you direct, but it bounced...
>
>To this address or to the one on my web site? Note that to mail to
>that address it's necessary to type the address. An attempt to
>minimize spam. Not very useful, unless I change that old address.

I tried to send this again but...

--------------
Hi. This is the qmail-send program at mpls-qmqp-01.inet.qwest-dot-net.
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

<acmq-at-compuland-dot-com.br>:
Connected to 200.255.96.21 but sender was rejected.
Remote host said: 550 5.7.1 Access denied
-------------

Not sure why that does not work...

> > I was looking over your coil at:
> >
> > http://www.coe.ufrj.br/~acmq/tesla/mres6.html
> >
> > And noted you were having trouble with C2.  Would a capacitor like this:
> >
> > http://hot-streamer-dot-com/temp/Pc260028.jpg
> >
> > Be of use to you?  It is a variable vacuum capacitor made by Jennings
> >
> > CSVF-500-0315
> > 15kV
> > 12-500pF
>
>The value is ok, but the voltage is a bit low. For that application I
>need at least 20 kV. Maybe more, because when the gap quenches the
>energy oscillates in the L2-C2-L3-C3 network, and the voltage in that
>capacitor can reach 30 kV, ignoring losses.

It tests to only 17kV, so 30kV is far too high.

>The simple flat plate capacitor that I am using now works well,
>although it loses some energy in corona. Looks impressive at least.
>To avoid a variable capacitor, I determined the best capacitor
>value with "pinger" tests at low voltage, and then made a high-voltage
>capacitor with the required value.
>I could redesign the system for a higher mode, and so obtain a
>capacitor that has to sustain less voltage. But this is not so easy.
>With a higher mode, the required C1 and C2 capacitances increase
>faster than the voltage decrease, if I want to keep the same output
>resonator.
>
> > They take 15kV peak, 100 amps (but that is continuous RMS heating,  1000's
> > of "real" amps ;-))), 12- 500pF at the turn of the screw knob (turn the
> > power off first ;-)), and they have practically no loss.
>
>I looked at the web site. Very instructive about the capabilities of
>vacuum capacitors. There is just one thing that worries me, and that
>is not mentiones in their notes:
>The construction of a vacuum capacitor is not essentially different
>from the construction of a cold-cathode X-Ray tube! I imagine that
>if the breakdown voltage is exceeded, the capacitor will start to emit
>X-rays...

One is not supposed to exceed the breakdown voltage here ;-)  I was using 
an x-ray power supply to test it and at 15kV it measured less than 1uA of 
leakage.  Is that OK?  I am curious about x-rays from such things!  We use 
these all the time at work but at 13.56MHz.  This one was removed since it 
was so old and I pulled it from the trash.

>
> > This is just an old one I have laying around and have no use for.  It's
> > free and I'll shipping to you free to Brazil if you want it.  Let me know
> > if you can use it and the address to send it to.
>
>I thank you for your generous offer, but I think that it will be more
>useful in your experiments :-) For me, it would not be useful for my
>present system, and the next that I want to make will need a larger
>capacitor.

Ok, I just thought I found it a home, but I'll try harder ;-))  If anyone 
else can use this odd paper weight, let me know ;-))  Maybe nice for a toob 
coil...

>
> > I am very interested in your new transformerless coils ;-))
>
>Yes, they are curious. I like the thoretical aspects, that open
>a large field where the same ideas used in passive filter design
>can be applied, but for an entirely different objective.
>I still have to make one with some real output power, however.

The fast transfer could have great uses in things like the OLTC that have 
high losses.  Very interesting stuff!

Cheers,

         Terry
         terrellf-at-qwest-dot-net


>Best regards,
>
>Antonio Carlos M. de Queiroz