Re: New 4" Coil: MMC blows MMC Away??

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Original poster: "Jason by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jasonp-at-btinternet-dot-com>

Gary,

> The TDK caps you mention are strontium titanate doorknob (ceramic) caps.
> The dielectric losses in such caps are surely higher than in suitable
> polypropylene MMC caps, not to mention the temperature stability issue.  I
> would doubt that the performance of the doorknob cap would be superior.
> But aren't both multi-unit arrays of small (MMC) commercial units?

Yes, temperature stability is an issue - ceramic caps tend to vary in value
with temperature to a large degree. I had the same doubts as you with
regards to dielectric loss, but after testing a load of UHV-3A's on my mini
coil and seeing a performance increase of about 15% I had faith, and bought
some larger caps of the same series. Now m using 10 UHV-9As, 2nF 40kV each,
good for about 9ARMS. After a 10 minute run at 300bps on my 1.1kW coil the
temperature rise measured from the aluminium terminals was negligable
(educated guess on Pri. current about 40ARMS). Yes, in a way it is an MMC of
sorts, seeing is it is multiple small value capacitors. I guess I dont call
it an MMC because it is made of large commercial pulse caps, and not
hundreds of small value components. All my previous MMCs have been mounted
on 20mm x 3mm copper bus bar, so the only extra resistance was the MMC cap
leads, making a fairer comparison.

Best Regards,

Jason
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