Re: 8 kHz Tesla Coil

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

HI Gerry,

On 23 Sep 2005, at 10:53, Tesla list wrote:

> Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
>
> Hi Malcolm,
>
> No comment is a waste of time in the persuit of knowledge and
> truth.  I think I understand what you were getting at.   If one uses a
> wire size where the current density is low in the center (that I
> called a waste of copper), one might opt to fix that by using a
> smaller guage and this will result in an increase of AC resistance.
>
> One question unresolved in my mind is how important it is to have the
> optimum unloaded Q considering that once breakout starts, the coil
> becomes loaded and Q drops to a low number.  Is the issue just one of
> power dissapated in the wire or are there other issues???
>
> Gerry R.

A lot of people place a strong emphasis on the low loaded Q of the
system and claim that this makes secondary Q relatively unimportant.
However, it is demonstrably true (and a waste of money) that even an
unloaded Q as low as 40 (c.f. a loaded Q of about 10 e.g.) results in
an abysmal performance. I have always found that high unloaded Q
secondaries perform well. I put that down to two things: maximizing
output voltage on first ringup and maximizing energy retention with
light loading (e.g. air streamers) for a second bite of the cherry
within a single primary shot. At some stage I'd like to see (or
produce) a formula which produces an optimal secondary (nominated
topload included) for a given size coilform. By optimal I mean with
the highest inductance before or about the point where Q starts
dropping.

Malcolm