Re: Large MOT vs. Small MOT

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Brett Miller <brmtesla2@xxxxxxxxx>

Dan,

I second all that that David said, plus you've heard
that stuff from me already about a million times on
the telephone.  Nice that you were able to get an
opinion from an another successful tube coiler here in
the south.

One thing to consider when comparing your coil's
output to my 18-21 60pps output.  I have to disagree
that we know for a "fact" that that tube (a Ryazan or
"RY" russian tube) is capable of more than 12 inches.
If you recall, you were at my house that night I
managed to run one of my 813s to failure (when it
apparently arced internally after a 3 minute run).  At
that time I had not yet given you the Ryazan, and I
sub'd it in place of the tube which had just failed.
It did give diminished output when compared to the
tube I had been running before...even though it was a
"new" Ry in it's original cardboard box with logo.

So it could be that you are very close to your optimum
60 pps spark length here.  However, based on some of
the things you've told me on the phone, you could
tweak a few more things and get 14-16 inches from this
setup.  For instance, have you tried a large variety
of grid length resistance?  Finish installing those
taps.  Also, play with the vertical placement of the
feedback coil.  If you wanted to wind another feedback
coil you could try using less turns (15 or less
instead of 20).  That is something I never got around
to trying with the 813 setup (and something John Freau
suggested) and probably won't any time soon.
I'm sure John will have something to say on this
matter.  He has considerable experience with tuning
and optitimizing tube coils.

One vttc experiment I am getting excited about is
firing up the 304tl again.   Also, once I send in my
order for the staccato parts, we can double up on each
component and get one going for you, Dan.

Cheers,

-Brett


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

> Original poster: "David Rieben"
> <drieben@xxxxxxxxxxxxxxx>
>
> Hi Dan,
>
> I assume that you're running your coil in
> "continuous"
> and not in "stacatto"? In continous mode, 12 to 14"
> really ain't that bad for your setup. If you install
> a
> stacatto circuit driver, you can run it at a much
> lower
> duty cycle and therefore, run it at a much higher
> peak
> power level without destroying your tube and thus,
> get
> longer sparks in a "strobe light" effect.
> Cameron Prince built my stacatto driver for me and
> once I got the other wrinkles ironed out, I was able
> get near 36" strobe-like sparks from my single 833A
> driven coil. Cameron and I built our VTTCs roughly
> from Steve Ward's 833A VTTC design and have both
> obtained ~ 36" arcs with our coils in this manner.
>
> David
>
>
> ----- Original Message -----
> From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Wednesday, March 07, 2007 9:50 PM
> Subject: Large MOT vs. Small MOT
>
>
>  > Original poster: Dan Williams
> <coilerdude@xxxxxxxxx>
>  >
>  > I am in the process of buttoning up my 813 VTTC
> (can be seen at
>  > www.coilerdude.20m.com).  Tonight I tried a
> larger unshunted MOT in
>  > place of the small shunted one I was using.
>  >
>  > NO Difference Whatsoever.
>  >
>  > Spark length stayed the same, intensity stayed
> the same.
>  >
>  > This dosn't make allot of sense to me.
>  > Someone shed some light?  Maybe suggest what else
> I might try to
>  > increase spark length past my current threshold
> of 12-14"?
>  >
>  > Have added a few more taps and tried tuning, max
> seems to be 12-14"
>  > at this point.  I know for a fact that this tube
> is capable of much more.
>  >
>  >
>  > Dan
>  >
>  >
>  > Now that's room service!
>  >
>
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