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Re: MOT - PSU



In the UK it appears there are only two commonly used types, one of
which is the type Reinhard mentions below, which I have two of (OK its
easy as I am in the UK). I thought I might add a few more details and
ask a few questions at the same time:-

1.These xfmrs have some kind of thermal fuse or cutout built into them
(joined to the primary through a small blue jumper wire, possibly a way
of identifying them), anyone know what it is, what it does or is it
worth bypassing it, I've always left it connected ?

2.Can the smaller UK type MOT's be used as isolation transformers in the
altair-dot-org style circuit?

Another handy feature of these xfmrs is if you want to keep the xfmr to
use in the microwave it came from, for microwaving CD's to put on top of
your TC :-) the heater winding for the magnetron is terminated on spade
terminals, so no floppy flying leads to get in the way !

Thanks for any answers.

Max Erhard (UK)

Tesla List wrote:
> 
> Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net>
> 
> Hi Herwig,
> 
> > Original Poster: "Herwig Roscher" <herwig.roscher-at-gmx.de>
> > Hi fellow MOT coilers,
> >
> > For my new VTTC unfortunately I havn't found a
> > suitable plate xformer yet. Therefore I'm
> > thinking of using a couple of MOTs instead. My
> > YU-204 tube is intended for pulse use and will
> > require more than 2.5 kVdc I can get out of the
> > 1.8 kVrms MOTs used in this part of the world.
> 
> Snip.
> 
> Try looking for bigger microwave ovens with Gardner (U.K.)
> MOTs. These put out 2.3kV at 650mA rated (measured,
> too). Antiparallel both on the 230V side and series the two
> on the secondary side. Center tap the connection coming
> from MOT #1 and going into MOT#2 and ground it. That
> way, you will get 4.6kV-at- 650mA (making ~3kVA) without
> overvolting the secondaries of the MOTs. These Gardner
> MOTs are up to the job and their insulation is better than
> most of the MOTs, I have seen. If you want to go to the
> trouble to build a set of two (meaning 4 MOTS) isolation
> xformers you could use 4 of these Gardner units to get
> 9.2kVAC at 650mA (~6kVA). That should give your VTTC
> a smokinŽ (pun intended) hot output. Actually, I have run 4
> of these in series w/o isolation xformers and they held up
> beautifully in air. There was no corona to be seen in the
> dark. A 5th one in series (NOT of the Gardner type) didnŽt
> last long, before it arced to the core (not surprising).
> However, even then, the Gardner MOTs did NOT arc over
> or die.
> 
> The only problem is FINDING these brutes, but maybe
> youŽll have more luck than I did ;o))
> 
> Coiler greets from (and back to) Germany,
> Reinhard