Re: Magnifier questions

Tesla List wrote:
> >From julian-at-kbss.bt.co.ukThu Aug 15 12:27:23 1996
> Date: Thu, 15 Aug 96 13:58:36 BST
> From: Julian Green <julian-at-kbss.bt.co.uk>
> To: tesla-at-pupman-dot-com
> Subject: Re: Magnifier questions
> >Julian,
> >
> >The magnifier requires a really special gap system.  The coupling between
> >the pri/sec in a magnifier is about 8 times that of a normal small coil
> >so breakdown between primary secondary is normal.  To prevent this, you
> >can reduce the coupling a bit, drop the whole thing in oil or insulate
> >with many turns of thick polyethylene sheet wrapped against the inside of
> >the primary.  This wrap must extend well beyond the top of the primary
> >almost to the top of the secondary.
> >
> >Finally the tune on the primary is often the lumped tune of the secondary
> >and resonator combined!
> >
> >Richard Hull, TCBOR
> In what way is the spark gap different?  Is there some info on this somewhere on
> the net?

The gap must quench with a rapidity which few amateurs can master in most 
gaps.  A series quench rotary is best.  Although a special rotary and 
multiple series gap arrangement is often used to advantage.  I am unaware 
of a net post on the series quench design. RH

> Also if the resonant frequency of a magnifier is the lumped tune of both coils then
> the voltage rise must be greater in the first coil (in volts per turn) than in
> the resonator due to standing wave 1/4 wave.  Current being 90 degrees out of phase
> with voltage and current at a maximum means large gradiant in voltage.

Wrong!  The greatest rise always occurs in the resonator. RH.

 I assume it
> is better to generate the voltage in the resonator if insulation problems are to
> be overcome.  So i'll wind the secondary driver from thick wire.  Abit of a balancing
> act this, working out a good impedance match between driver and resonator.

This is correct!  RH.
> Julian Green.

Magnifiers can be made in a number of configurations.  Only heavy 
coupling and special gapping will make one outperform a standard two coil 
Tesla coil.

Richard Hull, TCBOR