Re: Secondary Q

["Kennan C Herrick" <kcha1-at-xxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

2.48?...A Q of 2.48??  I am shocked!...shocked!  Here, during all these
years of thinking about Tesla coils--over 60 of them, I will have you
know!--I've been under the misapprehension that Tesla-coilers depended
upon, cherished and highly valued...resonance!  But no..., no..., no... 
Q?...who needs it?  Resonance, even...who needs it?  With the power and
voltage of a Grand Coulee or a TMI or even, in better times, of a
Chernobyl, coupled thru a vast pile of pole pigs, who needs resonance?

I've always likened Tesla-coilers to those profound Asian monks who
ritually bong upon their magnificent bronze gongs.  But no, most of you
just pour on the coal.  While I strive to maximize output while
minimizing input, your goal is to maximize output while maximizing input.

Who cares if you can fry eggs on your secondaries?  It keeps the shop
warm.  Q of 0?  Not a problem!

Disillusioned in California,

Ken Herrick

On Sat, 04 Nov 2000 17:21:12 -0700 "Tesla list" <tesla-at-pupman-dot-com>
writes:
> Original poster: Terry Fritz <twftesla-at-uswest-dot-net>
> 
> Hi Kennan,
> 
> Disruptive coils have very low over all Q.  My big LTR's is about 
> 2.48 as
> shown in the graph at:
> 
> http://63.229.238.62/TeslaCoils/Misc/BigLtr-VvF.gif
> 
> This is how we can load up streamers and do other frequency altering 
> things
> and still get good output.
> 
> I think the discussion of Q really comes down to losses in 
> disruptive
> coils.  Since I used Sonotube, my streamer length may be about 5% 
> less than
> if I had used PVC.  A surprising amount of power is going into 
> heating the
> cardboard.  As you note, our voltage amplification is by impedance
> transformation rather than pure resonant ring up.
> 
> Of course, 5% is not a super big deal but the loss is surprising. In 
> a
> humid place, it may become a real problem.  In a CW coil, heating 
> could
> become a real issue since the tube could get hot enough to burn if 
> you are
> really pushing a lot of power into the system.  Q is far more 
> important in
> the CW case.
> 
> BTW - Tesla had some nice CW coils too in teh 1900's that ran off 
> high
> frequency alternators.  However, unlike our disruptive coils today, 
> he
> would not recognize most of the parts of today's solid state 
> machines.
> Tubes were the "modern" thing in his time so he would not have a 
> problem
> with that  ;-))
> 
> Cheers,
> 
> 	Terry
> 
> 
> At 01:30 PM 11/4/2000 -0800, you wrote:
> >There's been a bit of discussion of secondary Q recently that leads 
> me to
> >ask how all you 19th-cy. spark-gap types (the vast majority!) 
> manage to
> >utilize decent Q at all:  Your tuning is imprecise due to 
> difficulty in
> >getting primary resonance to match that of the secondary; and
> >also--certainly when using a secondary with a Q as high as 80-100, 
> which
> >I've measured for mine--because the secondary's resonant frequency 
> is not
> >only "hard to find" but also it is going to shift markedly whenever 
> a
> >conducting surface gets anywhere near it.  You've got two resonant
> >circuits searching for each other, so to speak, with not a whole 
> lot of
> >continuing success, I should think.  
> >
> >I'm aware of the assertion that the energy stored in the primary
> >capacitor gets put into the secondary capacitance, less that lost 
> due to
> >gap loss and to primary:secondary coupling inefficiency.  So if the
> >capacitance ratio is 100:1 and you start out with 10KV on the 
> primary one
> >then theoretically you end up with a respectable voltage in the
> >secondary's capacitance prior to the zap.  But where, then, does
> >resonance come into it, and how are you going to gain, 
> particularly, by
> >having a high-Q secondary?
> >
> >Perhaps I'm too much of a purist but I stick with my s.s. system in 
> which
> >there's only one resonant item, the secondary, and that item itself 
> is
> >the resonant element in a feedback primary-driving oscillator 
> circuit. 
> >Always spot-on, resonance-wise, cycle by cycle.  So with my scheme, 
> the
> >higher the Q the better since higher Q facilitates higher voltage
> >build-up prior to the spark.  
> >
> >Comments?
> >
> >Ken Herrick
> >________________________________________________________________
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> >
> 
> 

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