Re: Secondary Q

[Terry Fritz <twftesla-at-xxxxxxxxxx>]

Hi Kennan,

When you consider that maybe 40% of the coil's power is lost in the gap,
the overall system Q is going to be bad...  If one looks at the Q loosly as
total energy divided by energy lost, 100 / 40 = 2.5 

Cheers,

	Terry

At 08:39 AM 11/6/2000 -0800, you wrote:
>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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