Re: Skeleton secondary?

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Jolyon,

On 27 Nov 2002, at 10:49, Tesla list wrote:

 > Original poster: "Jolyon Vater Cox by way of Terry Fritz 
<twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
 >
 > Dear List,
 >
 > Having noted that most secondaries are wound on solid tube formers, are
 > there advantages in winding a secondary on on a "skeleton" former (i.e.
 > circle of several insulating supports or tubes) for instance to minimise
 > self-capacitance?

Doing that hardly affects the self-capacitance (Medhurst's formula,
for example, doesn't take any account of former material) and, unless
the coil is really large and impractical to obtain a former for, a
waste of effort. I did it once purely for the heck of it (17" dia
coil).

 > Moreover would there be an even greater advantage in employing a "Lorenz"
 > type secondary (where the wire is wound between  supporting poles
 > numbered 1 to 8 so the wire passes over 1 under 2 and 3 ,over 4, under 5
 > and 6, over 7 and so forth so that each complete turn is see end-on as an
 > 8-pointed star with the wire having been wound over all eight poles)
 > from the capacitance-reduction point of view?

Again I think it's a waste of time and effort. Unless there are a lot
more than eight supports, the coil will end up being quite misshapen.
What's wrong with a typical secondary with a Q of several hundred?

Regards,
Malcolm