Re: Secondary coatings
Subject: Re: Secondary coatings
From: richard.quick-at-slug-dot-org (Richard Quick)
Date: Sat, 30 Sep 1995 07:06:00 GMT
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Quoting Ed H.
> On the subject of coatings:
> Richard Hull (or TCBOR) mentions in the guide to the Colorado
> Springs notes that he/they don't use secondary coatings
> anymore-or at least they were using only a single thin coat.
> He says they avoid breakdown from the coil by proper terminal
> Any comments on Hull's method?
Yes, Hull's method works just fine. Many times I have test fired
a coil with no coating whatsoever. While coating is not an
absolute necessity, it is worthwhile for several reasons.
1) Coatings prevent the winding from loosening and slipping off
the coil form.
2) Coatings decrease the chances of a coil suffering permanent
damage as a result of over-coupling and "splitting".
3) Coatings provide physical protection to the winding and help
prevent serious damage to a coil that may result from bumps,
dings, cuts, falls, etc.
4) During experimentation a coiler may choose to deliberately
over-drive the coil, the coil may be overdriven accidently, or
the coil may be fired in unusual configurations where the
electrical stress may be high (Tesla Magnifier and bi-polar
configurations for example). The coating does reduce corona
losses and reduces the incidents of electrical breakdowns.
5) A well applied coating looks good, and can be maintained.
I guess the argument here is that if you are winding a coil to
become part of a permanent system where changes are rarely or
infrequently made (like a museum or display coil) one or two
light coats of sealant, or just enough to stick the windings
down, would be fine. Once tuned and adjusted with a proper toroid
the coil will function well, and without excessive corona losses.
But on the other hand if you are like me; a person who frequently
removes/replaces/stores coils, changes primary configurations,
gaps, caps, dischargers, fires an occasional Magnifier or bi-
polar system, etc.. The benefits of a good heavy coating are
clear, if for no other reason than protecting the winding from
accidental physical abuse.
I have found that the benefits of a heavy coating on the
secondary far outweigh the advantages of a light or non-
existent coating. Also, there are a lot of beginners out
there. Beginners especially need the physical and electrical
ruggedness that a heavy coating provides.
... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12