Re: Optimal Quenching Tests

To: tesla-at-pupman-dot-com
Subject: Re: Optimal Quenching Tests
From: Bert Hickman <bert.hickman-at-aquila-dot-com>
Date: Tue, 07 Jan 1997 06:52:10 -0800
Subscriber: bert.hickman-at-aquila-dot-com Tue Jan 7 21:53:52 1997
Tesla List wrote:
> 
> Subscriber: FutureT-at-aol-dot-com Mon Jan  6 22:36:27 1997
> Date: Mon, 6 Jan 1997 23:00:20 -0500
> From: FutureT-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Re: Optimal Quenching Tests
> 
> In a message dated 97-01-06 00:55:41 EST, you write:
> 
> << snippity >>
> >The really wierd thing, is that IF you quench at, or before, this point,
> > the frequency splitting in BOTH the primary and secondary goes away. Ed
> > Phillips and Richard Hull mentioned some time back that the grizzled
> > veterans of spark radio knew all about this phenomenon, and used it in
> > high power systems! The Corum's only rediscovered it - they probably
> > hadn't yet been born when this approach was being used!   :^)
> 
> I wonder though, does the spectral splitting really go away, or are its
> effects just minimized?  It seems to me that for the notch to form in the
> first place, there must be spectral splitting occuring (this causes the
> beating which causes the notch).  (more below).   Or do you mean that the
> splitting goes away AFTER the quench?  There can be no splitting after the
> quench since the primary is open, and can't interact with the sec, thus no
> beating and no splitting occurs.   Splitting always stops at the time when
> quench occurs, regardless of when the quench occurs, whether it's quench at 1
> st notch, 2nd notch , 3rd notch , etc.
> 

I actually goes away (at least per my PSPICE analysis)! And apparently,
is backed up by results of high-power spark gap transmitters and recent
experimentation (per earlier posts on this phenomonon from Ed and
Richard. I did a Fast Fourier Transform analysis where the ONLY thing I
changed was the gap "on" time. Once I hit the optimal value, or below,
the twin peaks in primary current and secondary voltage went away, to be
replaced by a single peak at the commen resonant frequency of primary
and secondary. If I "detuned" the primary to be lower (as most of us
do), I STILL got one peak, centered at the secondary's resonanct
frequency as long as I optimally quenched. I don't fully understand
exactly WHY this should be, but it IS real...

> >  snip

> 
>  >This may be why a seemingly poorly-quenching gap, such as Cox's
>  >Milwaukee Museum coil with the beefed-up, but reliable, rotary
>  >electrodes, can still belt out 10 footers! Even on my lousy
>  >static/vacuum gap system, once the top-end really starts cookin',
>  >"effective" quenching performance improves, and I'll hit 1-2 primary
>  >notches consistently at 360-420 BPS.
> 
> This is really interesting, I wonder also if the use of tungsten electrodes
> significantly helps the quenching on Cox's system, I remember that someone
> suggested this recently on this list--that less metal is vaporized so it's
> easier to quench.

This would seem to make sense. Thermal conduction has got to be a much
better cooling agent than gaseous convection, even it we're blowing air
at the stationary electrode. 

>  >> 6)  When I quenched at 8 us in the above example,  I saw no notches in
> the
>  >> secondary waveform;  I saw only a build-up, followed by a nice high
> amplitude
>  >> ring-down.  But yes, I agree, more work needs to be done to verify the
>  >>  optimal quenching conditions needed for optimal spark output.
>  >>
> 
> > This makes sense - if we quench once the energy flow from
> > primary-secondary has completed, but before it can reverse, then we'll
>  >never see a secondary notch! A real poser is why the spectral splitting
>  >also seems to go away...
> 
> Certainly once the gap quenches, spectral splitting is gone, but I would
> speculate that there is some spectral splitting occuring before the gap
> quenches, even on first notch quench, but this splitting may not have time to
> beat and re-beat with all the frequency and out of phase components that
> occur during beating.  Thus with a slow or bad quench (and insufficient spark
> loading to lower the Q), the beating and re-beating may get "out of hand"
> (and out of the sec coil--as racing sparks)?

Before doing the simulation, this is what I thought as well. Certainly
the latter effect seems to occur... Now all I need's a GOOD gap system!

> 
> > > Happy coiling!
>  >
>  >>    John Freau
>   >>
> >    --Bert--
> 
> John Freau

Safe coilin' to you!

-- Bert --