Re: VTTC MOT doubler, is it safe?

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

Original poster: humanb-at-chaoticuniverse-dot-com 

Hi Jim, good to see you making progress. Don't be
discouraged as VTTC's are real dance. Also my 803
design was done when I was first starting out with
tubes, and I have never revisited it since. Definitely
better designs out there, but if you are getting sparks
then at least you have the basics down. Still really
recommend getting a variac, I had none in the beginning
and I still don't know how I didn't kill more tubes!
833's make for a nice VTTC and can be found on E-Bay
for $20-$40 each (or less), but Caveat emptor! Here is
one:
http://cgi.ebay-dot-com/ws/eBayISAPI.dll?ViewItem&item=3059324888&category=48710

Good luck,

David Trimmell

On Mon, 17 Nov 2003 07:18:43 -0700, "Tesla list" wrote:

 >
 > Original poster: "Jim Mitchell"
 > <Wrenchead-at-starband-dot-net>
 >
 > I tried the doubler, much bushier thicker louder arcs,
 > not too much length
 > increase, I noticed the plate getting a red spot after
 > a short run though, I
 > am wondering why I only get 5-7" arcs when people talk
 > of 19" and such, my
 > design is based on the 803 desing from
 > www.chaoticuniverse-dot-com, and I have
 > the primary tapped at various points which I can
 > change, would anyone happen
 > to have an 833 for sale?
 >
 > Regards - Jim Mitchell
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Sunday, November 16, 2003 10:35 PM
 > Subject: Re: VTTC MOT doubler, is it safe?
 >
 >
 >  > Original poster: Mike Poulton
<mpoulton-at-mtptech-dot-com>
 >  >
 >  > Mike Poulton Wrote:
 >  >  > Original poster: "Jim Mitchell"
 > <Wrenchead-at-starband-dot-net>
 >  >
 >  >  > Hi,
 >  >  > I recently completed my first VTTC, it uses an
 > 813 tube and a MOT from
 > a
 >  >  > 1200w microwave.  I am getting about 5-7" sparks
 > from the breakout
 > point
 >  >  > during good conditions, and I was wondering
would
 > it be at all possible
 > to
 >  >  > overdrive this tube and use a doubler on my
MOT?
 > The tube has a max
 > 2200v
 >  >  > plate, and I am afraid if I put doubled MOT
power
 > into it, it will form
 > a
 >  >  > fatal arc inside or somthing.  The tube has a
 > graphite plate, so Im not
 > too
 >  >  > worried about it melting or anything, but I am
 > afraid of arcs
 >  >  > inside.  Also, I am not running the tube in
 > optimum conditions, I have
 > the
 >  >  > screen and control grid tied together, and the
 > beam plate tied to
 > ground,
 >  >  > should I change it so that the screen is tied to
 > B+  by a resistor,
 > will
 >  >  > this increase my output noticalbly?  If not, I
am
 > going to spend some
 > big
 >  >  > bucks on a few 833's
 >  >
 >  > Most MOT's seem to produce about 2000-2500V, which
 > is already right at
 >  > the tupper limit for that tube. Doubling it will
 > give 5-6kV, which is
 >  > far more than the tube was designed to take. I
 > certainly wouldn't try
 >  > it. You should be able to max out the MOT's power
 > handling
 >  > capabilities without voltage doubling. Take a look
 > at the input power.
 >  > If you have high input power and are only getting
 > 5-7" sparks, then
 >  > something is wrong.  More likely, it is not drawing
 > much current
 >  > because the impedance of the coil is too high.  Try
 > better coupling or
 >  > fewer primary turns.
 >  >
 >  > -------------------------------------------------
 >  > Mike Poulton
 >  >
 >  >
 >  >