Re: Hi Q Quest (was sync TC latest results)

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: Hi Q Quest (was sync TC latest results)
From: Tesla List <tesla-at-stic-dot-net>
Date: Tue, 11 Nov 1997 22:32:17 -0600
Approved: tesla-at-stic-dot-net

From:	Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent:	Tuesday, November 11, 1997 8:17 PM
To:	Tesla List
Subject:	Re: Hi Q Quest (was sync TC latest results)

Hi John,
         
> From:   FutureT-at-aol-dot-com [SMTP:FutureT-at-aol-dot-com]
> Sent:   Tuesday, November 11, 1997 10:45 AM
> To: tesla-at-pupman-dot-com
> Subject:    Re: Hi Q Quest (was sync TC latest results)
> 
> > I replaced the 4 1/4" x 23", #28 formvar secondary with a 17" x
> > 17" #24 pvc insulated wire secondary also on a polyethylene form.
> > The new secondary has 470 turns, L = 67mH, F = 110kHz with 
> > toroid.  The old one had 1500 turns, L = 44mH, F = 135kHz with
> > toroid.  Based on wire resistance and reactance the new coil 
> > should have a much higher Q, but I didn't measure it.  Perhaps
> > the pvc insulation hurts the Q?  Coupling is k = .1 for either 
> > secondary.
> 
> All,
> 
> I'm updating my own post here:  I measured the Q of the new 
> coil using a 600 ohm signal generator, the results may not be
> precise because of the generator impedance, but the results
> should give some idea of the relative Q's.  The Q of the new
> coil = 192.  Q of the old coil = 100.  Yet, the old coil with the 
> thin #28 wire gives 46" sparks at 700 watts.  The new higher
> Q coil requires 800 watts to give the same spark length.  I can
> only conclude that the physical size of the new secondary is
> so large, and has so much isotropic capacity, that it is too much
> for the input power to handle.  For a proper comparison of Q's, a
> secondary of the same size but higher Q would have to be built,
> but that is difficult to do.  BTW, I had posted the incorrect freq.
> for and L value for my 4 1/4" by 23" secondary, but I corrected it
> above; (44mH, 135kHz). 

Going by Medhurst, your 17 x 17 will have considerably more 
capacitance (about 50% more). That would affect Vout. The same 
terminal as you were using with the smaller coils would have less 
capacitance on the bigger one though if my experience is anything to 
go by so the thing would be self-compensating to some extent.

> The large secondary required that the toroid be raised 8" 
above 
> the secondary to give best results.  The small narrow secondary
> seemed less affected by toroid height.  I can only conclude that
> when the toroid greatly overhangs the secondary, it's height 
> becomes less critical.  I've also seen this effect in tests of other
> coils.
> 
> Using the small toroid, the spark was about the same length
> using the high Q secondary, as with the low Q secondary, but
> the sparks may have been brighter with the high Q secondary.
> 
> These tests suggest that for best results, most of the isotropic
> capacity should be contained in the toroid, with only a small
> amount in the secondary.  But it is possible that I'm seeing the
> effect of some other unknown variable...there are so many 
> variables in TC work that wrong conclusions are easily reached
> when unknown variables are not controlled for.  That is why it is
> so important that people try to verify other's findings.  
> 
> Comments welcomed,
>  
> John Freau

Love to see that 17x17 used as an extra coil. Here is a scheme I've 
been using to achieve mag type operation : use a flat spiral primary 
with another flat spiral as the driver secondary on top of a 
separating acrylic sheet. All I got from doing this was that the 
closer the coupling, the better. 

Regards,
Malcolm