Re: srsg + mots - happy couple?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Conner <steve@xxxxxxxxxxxx>

> 5mm of the teflon
> would help us. or something is wrong with me again?

All that you said sounds pretty sensible. Personally
I've never had any trouble with my four choke array,
and I know someone who uses four MOTs in series with
the primaries and "I"s removed, to ballast a large
coil running off 10kV DC. If these work, you shouldn't
have any trouble winding your own inductor. But I have
heard other stories of people frying series strings of
MOTs.


> i have to measure the coupling coefficient
> between the
> primary and secondary of each of my particular mot.
> is it OK?

That method sounds like it would work fine. I did it a
different way though: I measured the DC resistance of
both windings, then measured the leakage inductance by
shorting the secondary, driving the primary with a low
AC voltage, and measuring how much current it drew.
Z=V/I and then Xl=sqrt(Z^2-R^2). Where R=
Rpri+(Rsec/turns ratio^2) This doesn't take saturation
into account though.

> and one more question - i need Ls as much as
> possible - are the shunts
> influence this?

The shunts look identical to a ballast inductor, that
is an inductor in series with either the primary or
the secondary. The parameter that they influence is
the leakage inductance as I measured above. (or K,
it's the same thing) They do store energy.


> why people must fight with such
> crap? they deserve
> better lot - MOT :-D

Well, I see people killing MOT stacks too! :-P The
insulation on the outer pair of transformers tends to
fail if it gets hit by transients. I'm sure your
scheme with the rectifier and secondary side ballast
will help though. Like you said, the voltage on the
MOTs is lower because some of it appears on the
ballast, and the ballast should also help to choke out
high frequency spikes.

I think what mostly kills transformers and ballasts is
primary strikes. You get a huge spike of voltage that
tries to fight its way back through the power supply
to ground. Safety gaps between the HV terminals and
ground might help that.

Steve Conner
http://www.scopeboy.com/