Re: Magnifier coupling measurements, new (fwd)

---------- Forwarded message ----------
Date: Fri, 10 Jul 1998 09:36:05 +1200
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Magnifier coupling measurements, new (fwd)

Hi John,
           Thanks for the further measurements of magnifier k's. I 
have two comments:  Firstly, the overall k of my system was almost an 
order of magnitude below the driver itself because the driver 
secondary had such a small fraction of total secondary inductance. 
Driver Ls was about 350uH and resonator around 7mH if memory serves 
me sufficiently.
> ---------- Forwarded message ----------
> Date: Tue, 7 Jul 1998 09:10:48 EDT
> From: FutureT-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Magnifier coupling measurements, new
> All,
> In these tests, I looked at the primary current waveform by using
> a current transformer attached to an oscilloscope.  These tests
> provide further verification that despite the tight coupling of a 
> magnifier driver, the overall coupling of a magnifier is loose, and is 
> typically within the range of two-coil Tesla coils.  (In my previous
> tests, I looked at the secondary or extra coil waveforms.)
> I used the same old set up with pri, 19 turns, # 12 wire, sec, 1.5mH
> 6.5" dia by 3.4" high, # 24 pvc, driver k = .4, extra coil = 11.4 (13?)mH.
> 3" by 12" # 28 formvar, tank cap = 0.0015uF, Fo = ~500kHz, toroid is
> 1.5" by 4.5", synch gap 8 point series quench type, (4 points used),
> powered by 10kV, 23ma oil burner ignition transformer.  A variable tune
> cap (34pF to 167pF range) is installed across the secondary.

> Figuring the effective or actual coupling based on a 28uS beat, gives
> k = 0.07 which is quite a low figure.  But it compares well with Malcolm's
> results where his 0.54 driver k fell to k = 0.086 actual overall system k.

<more snip>
> Also interesting was the appearance of the secondary (?) waveform.
> It did not show normal energy transfers, but rather had a flat
> shape (except at the beginning), but I may have been picking 
> up some of the extra coil's energy, and this may have given a false
> appearance to this waveform?

I think you may be picking up some of the primary. I too found this 
problem confused my results until I realised what was happening and 
repositioned the probe and coils.  ?perhaps?

Thanks for an exceedingly interesting post.