Re: DRSSTC Tuning Paper (Rough Draft)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Dan,

I ran numbers with Javatc on your data (thanks for sending). By 
referencing your data here and your write up, aspects were easy 
enough to retrieve. I went through and ran the uncoupled pri and sec 
numbers then the coupled numbers.

Pri (uncoupled):
Dan       159.9 kHz   9.2uH   5.5 turns
Javatc    159.6 kHz   9.2uH   5.5 turns

Sec (uncoupled):
Dan       288 kHz   39mH (the measurement seems high. Maybe someone 
else can verify?).
Javatc    330 kHz   37.6mH

Sec + toroid (uncoupled):
Dan       198 kHz
Javatc    200 kHz

Pri, Sec, + toroid (coupled):
Dan       not indicated (only upper and lower resonant modes)
Javatc    198 kHz

I don't see anything wrong here. If the coil was autotuned (and 
adjusted to keep top of primary even with bottom secondary turn) 
Javatc would end up at 4.2 turns (and Javatc would be right). Dan has 
shown in his paper that his coil favors a detuning high on inductance 
of about 19% (Dan showed as operating nearer the lower resonant 
mode). I have detuned coils high on inductance up to 13% on occasion 
for best operation and they were sparkgap coils. Typically, 5 to 8 % 
seems to be the norm there.

What Dan has found through his measurements is that arc loading 
detunes the system. By detuning the primary, the "loaded" system will 
pull towards resonance as the arc length is reached (versus falling 
away from resonance which is what can happen if the system is tuned 
without spark loading in mind). This is not new, but there may be 
more loading for a given arc length on a DRSSTC vs a sparkgap coil? I 
guess that is what I'll be looking out for on these systems. Neat stuff!

Take care,
Bart



Tesla list wrote:
> Original poster: "Mccauley, Daniel H" 
> <mailto:daniel.h.mccauley@xxxxxxxx><daniel.h.mccauley@xxxxxxxx>
>
> Here are the coil specifications:
>
> Toroid:  13" x 4"
> Secondary:  4.5" x 12" winding length
> Secondary Wire:  30 AWG
> Primary Coil:  Approx. 5.75 to 6.00 turns of 0.25" tubing (0.20 spacing)
> Primary Capacitor:  0.108uF
>
>
> Secondary Coil 1st turn is approximately equal to the top turn of
> primary coil.  Spacing between toroid and top turn of secondary is about
> 2 inches.
>
> Hope this helps.
>
> Thanks
> Dan
>
>
>
> Dan,
> thanks for the information. JAVATC uses raw geometry to calculate the
> resonant frequency, coupling factor, recommended tuning point etc. So
> it would be easier if I had some of the coil specs. However, I can
> input some guesses until the electrical parameters match what you have
> here.
>
> I assume the Cprimary is 0.108uF.
>
> Thanks
> Jim
> ----- Original Message -----
> From: <mailto:tesla@xxxxxxxxxx>Tesla list
> To: <mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx
> Sent: Thursday, June 29, 2006 3:52 PM
> Subject: RE: DRSSTC Tuning Paper (Rough Draft)
>
> Original poster: "Mccauley, Daniel H"
> <<mailto:daniel.h.mccauley@xxxxxxxx>daniel.h.mccauley@xxxxxxxx>
>
> Jim,
>
> The actual tuning point is shown in the paper.  This equates to 9.2uH of
> primary  inductance.
>
>
> Lsec= 39mH
> Coupling = .14 (for 9.2uH tuning point)
> Cpri = 0.108uH
> Csec(total) = 17.5pF
> Rsec = 150