HV pwr xfmr -- good idea?

[Richard Carroll]

Brian Carling wrote:
>
> If it is such a disadvantage, WHY do they do it???
>
> Are there other "shorting" methods like this?
>
> Bry
>
> On 21 Jan 98 at 19:05, Don wrote:
>
> > I was under the impression that microwave HV transformers use hysteresis
> > flux limiting to limit the power delivered to the klystron in case of
> > mismatched loads (an everyday occurrence in microwave ovens).  Those I have
> > seen apart have a weld bead across the laminations in one or more places,
> > which would seem to support this hypothesis.
> >
> > Flux-limited transformers make very "soft" (poorly-regulated) power
> > supplies, and dissipate lots of power in the transformer (high no-load loss
> > that gets larger and larger as the load increases).
> >
> > Don
> ****************************************************
>

  The answer to that would seem to be to limit the power supply current
available to the klystron so that it doesn't destroy itself when poorly
loaded, like a tube type ham xmtr can when a stiff power supply is used.

  The welded bead across the laminations would seem to be the key to
this added hysterisis factor and perhaps the weld could be ground or
sawed out, and the laminations seperated and insulated from each other
as in normal transformers, but the microwave oven transformers I have
seen seem to use the weld(s) as a part of their structural integrity,
so that would dictate other means of holding the transformer together. I
abandoned the idea after all these considerations came into play.

Dick W0EX

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