Re: [TCML] Tuning a new coil : Reality vs JAVATC

["DC Cox" <resonance@xxxxxxxxxxxx>]

Which brings to mind a question.

Bart --- do you account for streamer length in JAVATC, ie, do you add some
topload capacitance to give the best pri configuration based on added
streamer capacitance, or does it just do distributed capacitance and topload
capacitance in the calc?

Dr. Resonance




On Tue, May 27, 2008 at 12:11 PM, b alex pettit jr <a_pettit_jr@xxxxxxxxx>
wrote:

> Continuing with this project ....
>
>  I just ran several tests measuring the F_res of this 4.5" dia x 21" 940
> turn coil.
>
>  I drove the primary ( without cap) via sig.gen and measured the coil's
> response
>  on a freq.counter and scope. It was quite evident the coils F_ res was
> 268.98 KHz.
>  Half Power points at 268.3 KHz and 269.5 KHz = a Q of 224  and well
> correlated
>  to  JAVATC's Q calc of 285. (The Primary and lower end of  the Secondary
> were tied
>  to my in-ground copper stakes)
>
>  With slight tweaks in ground plane and adding a turn or two to the Sec
> parameters,
>  JAVATC calculated a F_res = 268.86 KHz ( as close as I felt needed to
> match 268.98 KHz).
>
>  The Rest of The Story:
>  That F_res via JAVATC tunes the Primary at 6.797 turns, a HalfPower point
> at 6.777.
>  With a 45" circumference of the Primary at turn 7, this equates to +- 3/4"
> from resonance
>  to half power point frequencies.
>
>  BUT,
>    I added a 'StreamerLoad " wire of 36" , it detuned the F_res by 30 (
> thirty ) Hz !
>
>  This changes the Primary tuning point to 7.751 turns ...a full turn !
>
>  How does one actually Tune a Tesla Coil ?
>
>  I am considering a banjo type coil element equal to  1/3rd turn of the
> main primary to
>  use for experimentation.
>
>  Or, how precise IS the tuning of Pri to Sec ?
>
>  I know that in lightly damped mechanical structures, the frequency of the
> excitation is
>  extremely critical for full excitation.
>
>  This is becoming a tail chasing dog senario...  am sure also changes in
> coupling factor
>  detune the system ...
>
>  good news,
>  multigap spark gap is working and streamers are exceeding 24 inches...
>
>  Thanks,
>  Alex P
>
>  ********************************************************************
>  J A V A T C version 11.8 - CONSOLIDATED OUTPUT
> Tuesday, May 27, 2008 2:32:20 PM
>  Units = Inches
> Ambient Temp = 68°F
>  ----------------------------------------------------
> Surrounding Inputs:
> ----------------------------------------------------
> 38 = Ground Plane Radius
> 100 = Wall Radius
> 100 = Ceiling Height
>  ----------------------------------------------------
> Secondary Coil Inputs:
> ----------------------------------------------------
> Current Profile = G.PROFILE_LOADED
> 2.26 = Radius 1
> 2.26 = Radius 2
> 2.3 = Height 1
> 23.3 = Height 2
> 943 = Turns
> 24 = Wire Awg
>  ----------------------------------------------------
> Primary Coil Inputs:
> ----------------------------------------------------
> 4.25 = Radius 1
> 7.647 = Radius 2
> 3.3 = Height 1
> 3.3 = Height 2
> 6.793 = Turns
> 0.25 = Wire Diameter
> 0.0187 = Primary Cap (uF)
> 0 = Total Lead Length
> 0 = Lead Diameter
>  ----------------------------------------------------
> Top Load Inputs:
> ----------------------------------------------------
> Toroid #1: minor=3, major=12, height=30, topload
>  ----------------------------------------------------
> Secondary Outputs:
> ----------------------------------------------------
> 268.86 kHz = Secondary Resonant Frequency
> 90 deg° = Angle of Secondary
> 21 inch = Length of Winding
> 44.9 inch = Turns Per Unit
> 0.00217 inch = Space Between Turns (edge to edge)
> 1115.9 ft = Length of Wire
> 4.65:1 = H/D Aspect Ratio
> 28.4093 Ohms = DC Resistance
> 30794 Ohms = Reactance at Resonance
> 1.36 lbs = Weight of Wire
> 18.229 mH = Les-Effective Series Inductance
> 20.096 mH = Lee-Equivalent Energy Inductance
> 19.905 mH = Ldc-Low Frequency Inductance
> 19.223 pF = Ces-Effective Shunt Capacitance
> 17.437 pF = Cee-Equivalent Energy Capacitance
> 32.248 pF = Cdc-Low Frequency Capacitance
> 5.61 mils = Skin Depth
> 11.652 pF = Topload Effective Capacitance
> 108.1284 Ohms = Effective AC Resistance
> 285 = Q
>
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>
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