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Re: Magic K values



Tesla List wrote:
> 
> Subscriber: sgreiner-at-mail.wwnet-dot-com Wed Jan 29 21:02:12 1997
> Date: Wed, 29 Jan 1997 16:55:26 -0800
> From: Skip Greiner <sgreiner-at-mail.wwnet-dot-com>
> To: tesla list <tesla-at-pupman-dot-com>
> Subject: Magic K values
> 
> Hi Bert H. and All
> 
> In December Bert was kind enough to post a list of magic K values and
> their derivation.
> 
> I have a question. These values are derived from parameters which are
> measured when the TC is not energized. We all know that for various
> reasons the resonant frequency of the secondary goes down while
> energized due to the fact of the ion cloud and possible other factors.
> With this in mind how can the K values be accurate? Furthermore, it
> seems to me that
> different toroidal loads on different secondaries would give different
> amounts of terminal capacitance so that one could not extrapolate values
> obtained from ststic measurements. If the numbers don't hold for
> different configurations, what good are they? I would appreciate any
> comments that the members might contribute.
> 
> Skip

Skip,

"Magic" k values are significant in that they permit "clean" transfer of
primary energy to the secondary in an _integral_ number primary
halversines. A non-"magic" K will run less efficiently in that it will
strand at least some energy in the primary tank capacitor, thereby
reducing the total energy transferred to the secondary. All things being
the same, go for the highest K your insulation system can withstand.
Ideal quenchtimes, adjusted for gap losses, _are_ useful for determining
appropriate rotary dwelltimes when designing a rotary gap. The good news
is that precise quenchtimes and k's are not all that essential. As long
as we allow MOST of the ringup to occur, and QUENCH before secondary
energy has a chance to flow back into the primary, you'll have good
performance. Using a "magic" value merely wrings the last ounce of
performance out of the system. 

Even if the secondary frquency declines a bit due to the increased
capacitance of the ion cloud, the effect on quenchtime should be
minimal. If we are in proper tune with a given secondary/toroid pair,
and we adjust K to as high a magic value as the secondary insulation
will withstand, and if we can truly quench at or near the "ideal" time,
the coil will function in nearly an optimal fashion.  

BTW, how's your micro-coil coming along??

Safe coilin' to ya, Skip!

-- Bert --