Re: Homemade chokes

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

Hi Bill,

On 11 Aug 00, at 18:31, Tesla list wrote:

> Original poster: "Bill Lemieux" <gomez-at-netherworld-dot-com> 
> 
> On that fateful day 8/11/00 12:23 PM, thus spake Tesla list:
> 
> > They certainly do when the primary includes a sparkgap which
> > is the norm for a disruptive coil. I worked all this out in a
> > paper several years ago. It should be in the archives
> > somewhere under the heading "PrimaryQ - A Brain Teaser".
> > The essence of it is that the gap cannot be modelled as a pure
> > resistance because if you include it in series with a tuned
> > circuit, the result is not a logarithmic decrement but a
> > linear one. You can actually see the linear envelope impressed
> > on the secondary e-field as pri-sec energy exchanges proceed
> > if you prevent the coil from breaking out.
> 
> Excuse me, I thought the original post concerned the Q of the primary alone,
> not the entire primary circuit, which I agree is a more complex impedance.

Is that really a practical consideration where the gap is 
always included in the primary of a running coil? I know where 
the equal Q idea comes from - the same principle says use 
equal masses of copper in the primary and secondary of any 
transformer so that there are equal losses in the primary and 
secondary. Which is OK for a steady state power throughput 
rather than the transient one which best characterises a cap 
discharge TC. Ideally, a TC primary would have no losses at 
all. Not easy to engineer but a very desirable situation to 
aim for I would have thought. Good secondaries already have 
very low unloaded losses. A primary with a gap in it is like a 
secondary with a permanent discharge hanging off isn't it?

Regards,
Malcolm