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Re. metal case caps
>Original Poster: dferguso-at-ebmail.gdeb-dot-com
>
>hello coilers- can anyone tell me if metal cased caps are ok to use in
>close proximity to the primary (like underneath the primary where many
>coilers place their cap) if it is steel, i take it that eddy currents
>would be a problem and cause unecessary heating and rob power from the
>secondary. how about aluminum or stainless, i am guessing that eddy
>currents wouldn't be a problem, but wouldn't the mag field of the primary
>induct into the capacitor case? would the capacitor case be 'seen' as a
>closed loop, which from what i understand is very undesireable , such as
>to have a closed loop on your secondary. the reason why i ask is that i'd
>like to make the case for my cap out of metal, since i am familiar with
>metal fabrication , the cap would look sharp, and the case would be
>rugged and leakproof. the cap would have a plexi top, and the plates,
>busses,etc would be adequately insulated from any parts of the metal
>case. any input on if i am missing something would be greatly appreciated
>- thanks, doug
I don't think there is any problem. The same situation exists for NST
cases, and when you think if it, if you take the case off of your cap,
what do you have? Metal plates.
I think the issue of eddy currents and other closed loops is often
overstated. I performed an experiment related to this once. I normally
have a strike rail just above the outermost turn of my primary,
consisting of a grounded loop of .25" copper tubing with a 0.75" gap
between the ends. For grins I shorted the ends with a piece of 20 gauge
wire and ran the coil. Performance was visably no different than without
the short, although the wire did become quite warm.
Gary Lau
Waltham, MA USA