Quote:
Originally Posted by Viewmaster
Arcing same place as before but have taken one turn off the top of coil and reconnected...seems OK now.
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That's good news! Drum roll, please!!!
Quote:
Originally Posted by Viewmaster
Coil dims...… height is 15 inches. dia is 4.5 inches. wire dia is .02 inches
About 750 turns...……..
...................….749 now because of above.
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Hey Albert,
From this, we can work out the following (approx.)
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Inductance, secondary coil: 16.7mH (roughly)
Self-resonant frequency of secondary coil assuming approx 10pF parasitic capacitance= 390KHz
This is likely to be rather higher in reality, as not only the break-out point but also the plasma itself has capacitance!
Inductance, primary= 170uH
(for peak resonance with parallel 1nF capacitor, as you indicate in post 31)
RF period=2.6uS
Ideal period of grid leak is 4-5 times this =say approx 10uS
With your 150W light bulb and 7nF, the period at the moment is 2.7uS
The grid leak is complicated, and of course we don't know except experimentally about the bias conditions of these triode-strapped pentodes, but it may be worth trying down to even 40W bulbs, just to see what happens
A 40W mains bulb a resistance of 1440R, compared to 384 for a 150W and the period goes to 10uS.
Grid leak period, 7nF capacitor
150W bulb =2.7uS
100W bulb= 4.4 uS
60W bulb=6.7uS
40W bulb=10uS
I'm not fortune telling and it may not have a beneficial effect, but then again, it may increase efficiency, which is always a good thing!
The best results that I've seen are when builders have an easy way to get the sweet spot for grid leak R.
Looking forward to more progress!