Re: Need Secondary wire source

["Malcolm Watts" <M.J.Watts-at-massey.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi Ken
        Having built several spacewound secondaries I have a 
few comments:

On 1 Aug 00, at 17:03, Tesla list wrote:

> Original poster: "Kennan C Herrick" <kcha1-at-juno-dot-com> 
> 
> [kch]  I'll intersperse a few comments:
> 
> On Mon, 31 Jul 2000 21:39:21 -0600 "Tesla list" <tesla-at-pupman-dot-com>
> writes:
> > Original poster: "acmnovak" <acmnovak-at-email.msn-dot-com> 
> > 
> > The fishing line method is quite messy and unreliable if you wind it 
> > by
> > hand. A friend of mine made a jig for space winding that gave him 
> > *perfect*
> > spacing on his big 8 inch coil. The result was a coil which produced 
> > 4+ foot
> > streamers from 1800 watts. 
> 
> <snipped>
> 
> [kch] Although I've not done it, I feel intuitively that simultaneously
> winding fishing line & wire is something I don't want to tackle.  I'm
> contemplating the winding-on first of a cotton twine to form a spiral
> track, with winding-pitch larger than the wire diameter.  After
> stabilizing that with, perhaps, a very thin varnish or "water seal"
> preparation, I would then wind the wire over the twine.  Comments,
> anyone?

I did try twine once but don't like it because some varieties 
if not all will give rise to uneven spacing. My favourite 
technique is two bifilar wind two lengths of the same gauge 
wire, then remove one progressively using gravity while 
applying some spray varnish to hold the clear turns in place.
 
> > 
> > My $.02 on spacewound secondaries:
> > They are a waste of time.
> > Don't bother unless you must use a smaller size wire than the 
> > optimum for
> > that diameter secondary.
> > Any dust or debris between windings on the coil will burn down the 
> > secondary
> > during operation. Not good!!!
> 
> <snipped>
> 
> [kch]  To the provider of the $.02 (Is it Mike H?):  You make a very good
> point.  Better to fill that space with a solid non-conductor.  Porcelain
> would be nice.  But more seriously, doing essentially as you suggest. 
> But then, what does one do about inadvertent carbon-tracking?  More
> comments, anyone?

I've never experienced it. As I once stated, you are not going 
to be able to push the wire insulation (let alone the space 
between the wire) that far. I have had far less trouble with 
tracking using spacewound coils which don't have an insulator 
filling the gaps than with closewound coils covered by screeds 
of varnish. To some extent I think the inter-turn gaps behave 
somewhat like fluted insulators. I do not agree with the 
expressed opinion that spacewinding is a waste of time. I am 
quite happy with it. Most large coils use it. My approach when 
choosing a secondary length is to base it on maximum projected 
output voltage. The wire spacing takes care of itself. 

> <snipped>

Regards,
Malcolm