Re: More MOT supply questions

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Hhchicken1-at-aol-dot-com>

Hi Mike,
I don't have an inductance meter, so I just chose the two MOTs with the largest
spacing for my outer two - in fact they were quite different core sizes etc so
the inductances were probably completely different, but it seems to work fine. 
OTOH, that was with my 6-pack supply and if you're only going for a 4-pack,
spacing probably doesn't matter so much - especially under oil.  I'd say as
long as the inductance-matching ones have at least a couple mm of space you'll
probably be fine.

Henry

In a message dated 16/10/2002 15:44:40 GMT Daylight Time, tesla-at-pupman-dot-com
writes:


>
> Original poster: "Michael Strube by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <mjstrube-at-earthlink-dot-net>
>
> Thanks to all who weighed in on the crimp-solder-quick connect issue.
> Very helpful advice--amazing how such a seemingly simple question can
> have so many facets to it. 
>
> I have another question. I am now selecting the MOTs that will be part
> of the 4-pack that I am building. I have 30 or so MOTs around my shop to
> choose from and not a pair that are duplicates (not a rare situation I
> understand). All are of the 2200 volt variety. I know that the outer
> MOTs will need to hold off the higher-than-usual voltage and I've seen
> the recommendation to choose MOTs (usually older ones) that have the
> greatest winding-to-core spacing. I have a small number that would fit
> that bill just fine. But, they have different primary and secondary
> inductances. For example, one has a primary inductance of 46mH and a
> secondary inductance of 13H. Another has a primary inductance of 24mH
> and a secondary inductance of 7H. On the other hand, among the numerous
> small-spacing MOTs that I have, I can match up several pairs so that
> they have very similar inductances.
>
> So, the question: Is it better to have the outer MOT pair matched on
> inductances and not worry about the winding-to-core spacing, or, to make
> sure the winding-to-core spacing is large but the inductances
> mismatched? Can't have both at the moment and given the number of MOTs I
> have now and their wide variation, I'm not hopeful that further
> scrounging would allow matching inductances AND having large spacing.
> Let me add that the MOTs will be under oil (I'll occasionally use a
> level shifter design for this supply), so perhaps the spacing is less of
> an issue in my case.
>
> Thanks in advance for any help.
>
> Mike