WINDING PRIMARY

• To: tesla-at-pupman-dot-com
• Subject: WINDING PRIMARY
• From: "J. B. Weazle McCreath" <weazle-at-hurontel.on.ca> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Mon, 20 Dec 1999 22:11:17 -0700
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hello Coilers:

Here's my .02 worth on winding primaries from 1/4 copper tubing.  I used
this method on both my first coil which had only 8 turns, and on my next
generation one with 16 turns and larger overall proportions.

Taking the inside and outside diameters of the primary from WinTesla, I
calculated the length of the insulators/spreaders and cut them from a
sheet of 1/4" thick teflon using a table saw set to rip 1" wide strips.

I then constructed a drilling jig made from 1" aluminum channel which had
two 1/4" holes drilled in the bottom of the U, centered side to side and
spaced 1/2" apart.  I stuck a 1/4" bolt thru the first hole as an indexing
pin and left the second hole open.

Taking one of the teflon strips, I measured and then drilled a 9/64" hole
in from one end of the strip 1/4" and centered side to side.  This hole is
then placed over the indexing pin in the aluminum channel and the second
and subsequent holes are drilled in the strip thru the second hole in the
channel.  Simply advance the strip on the indexing pin until all of the
holes have been drilled.

This gives a very uniform hole spacing and if done with a drill press
rather than a hand drill, the jig can be clamped to the table and you
can drill all of the required strips in minutes.  The 9/64" holes are
a nice sliding fit for the 1/4" tubing and the coil is simply threaded
thru them starting from the outside.

Due to the loose fit, the angle of the "saucer" can be varied readily
and when the optimum angle is found wooden wedges can be cut and secured
beneath the teflon strips to secure them.  A few dollops of hot glue
does that job and can also be used to secure the tubing in the strips.

I made the jig, used it to drill the strips, and wound the primary, all
in about an hour and a half.  The finished primary is quite solid, well
insulated, and it even looks good!


73, Weazle, VE3EAR/VE3WZL

Listening: 147.030+ and 442.075+
E-mail:    weazle-at-hurontel.on.ca
           or ve3ear-at-rac.ca
Web site:  www.hurontel.on.ca/~weazle

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