New secondary worth effort

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "J. B. Weazle McCreath by way of Terry Fritz <twftesla-at-uswest-dot-net>" <weazle-at-hurontel.on.ca>


Hello Coilers,

With all the talk of winding secondaries lately, I got the urge to wind
a new one for my coil.  It's 4" x 22", which maybe is pushing the H/D
ratio a bit, but with number 22 wire I got 800 turns.  I used my tried
and proven method of first cleaning the form with tolyene, then a thin
layer of West System epoxy resin is brushed on while the form turns in
the lathe.  While the epoxy was still uncured I wound the coil using a
teflon block in the tool post to guide the wire onto the form.  It took
about 15 minutes to wind the entire coil which was then covered with a
layer of epoxy resin and allowed to cure with the lathe still spinning.
That last step is important to prevent runs and sags.  Three baffles in
the interior and purging with dry nitrogen before fitting the end plugs
made of kiln dried cherry insures against internal arcing.

Was the effort worth it?  You bet it was!!  With the extra inductance
compared to the original secondary, I can now use my entire bank of
MMC's, giving me 25.8 nF.   With just 200 Volts applied to the three
OBITs I'm getting three or four simultaneous discharges from the toroid
well over 2 feet long!  When I crank up the variac to 260 Volts, it gets
downright frightening...and the noise!  It sure is nice when you are
rewarded for your efforts.

The next step calls for replacing the OBITs with a MOT/voltage doubler
power source and a rotary gap.  Thanks to all on the list who passed
along suggestions and comments on various aspects of my coil as I was
building it, and to Chip and Terry in particular for maintaining the
archieves and moderating the list.


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