Re: VTTC MOT doubler, is it safe?

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

Original poster: FutureT-at-aol-dot-com 

In a message dated 11/17/03 9:28:41 AM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

>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?


Jim,

You may need to use 2 or 3 MOT caps in the doubler circuit for best
results.  The design of your coil is almost exactly the same as my
coil design which gives the 19" sparks.   The 813 tube is almost as
powerful as the 833A provided it can withstand the doubler.  Be sure
you have at least 23 turns in the primary when the coil is tuned
properly for longest sparks.  The addition of the doubler should
cause a tremendous increase in spark length, so the fact that
your spark length did not indicates a problem somewhere.  When
the grids are tied together like that, fewer turns will be needed in
the grid feedback coil.  For example if you had 20 turns in use,
you may need only 10 turns.  Also, you can move the feedback
coil farther away from teh primary instead.  Even without the doubler
you should get about 12" sparks from the 813 tube.  Make sure
your filament voltage is about 10.5 volts.  A low voltage on the
filament is very bad and will reduce tube life and will result in
shorter sparks.  Measure the filament voltage directly at the tube
socket or the tube pins preferably.

John