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secondary questions
Subject: secondary questions
Date: Wed, 16 Apr 97 00:46:42 UT
From: "William Noble" <William_B_Noble-at-msn-dot-com>
To: "Tesla List" <tesla-at-poodle.pupman-dot-com>
I'm dutifully following (most) of the RQ recommendations and the info
from
this list. I've made myself a 14 turn flat spiral out of 1/4 inch
tubing on
1/4 inch spacing with a 6 inch inner diameter, and now I've wound myself
a 14"
X 4" coil on PVC, following the instructions to spray urethane first,
then
wind, then spray more urethane. I should have (according to the radio
amateur's handbook, just under 650 turns (46.3 turns per inch) on this
secondary (I know, 900 is the recommended number, but I ran out of wire
at 14
inches). Anyway, my questions:
1. why is the initial coat of urethane needed??? I can see that it may
help
adhesion of later coats, but unless the PVC is electrically conductive,
a
layer of urethane ontop of the PVC won't affect dialectric constants by
a
measurable amount, or so it would seem - yet the RQ files make a big
deal of
this.
2. The RQ files say NEVER put any wire inside - yet it seems to me that
the
ground terminal is best done with a stove bolt through a PVC cap that is
then
wired to the secondary - why should wire not be inside the form at the
ends???
(of course not in the middle, but why not at the ends). Same general
comment
about the high side of the secondary - another bolt would be convenient
for
mounting a HV terminal or capacitor to, yet that would involve some wire
(or
at least a bolt head) inside the coil.