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[TCML] 3200 Turns Secondary

Hi all,

I thought I just share this information, for there there's not much info on
high turns secondaries.

Many times one can read not to wind too many turns above 1000.
So why did i do it?

I have a triggered SISG and so I want to lower the primary current peaks as
much as possible.
So I made the biggest secondary possible with the biggest possible
inductance while still being able to set everything up by myself.
The result is a 49" (1250mm) winding on a 12" (310mm) form, good for 3200
turns of #27 AWG (0.35mm).
The coil has an inductance of 718 mH and a dc resistance of 570 Ohm.
With the topload, an inox toroid of 24" x 6", the resonant f is 33 kHz, wich
is pretty low...

Primary is made of flat strap copper, tank cap = 200 nF.

Power supply = 6kV (4 MOT's bridge rectified series / parallel combination),
not the biggest MOT's but 4 the same, I guess 700W each, with removed
DC-resonant charging is used, so the SISG is a 12 kV version.

The result can be seen here:



Sparks of 60" no problem but 70"+ is hard.
I did expect longer sparks with the power available and the use of the
really high Q primary wich I could built now thanks to the low Fres...

So maybe there is indeed considerable loss in the secondary windings

I have somewhat the same results as with my previous coil, a 6" 1400 turns.

But: For that coil a 100 nF tank cap was the max I could use (Fres= 130kHz,
currents > 800 Amps) and I had no breakout from the toroid.
Now I can use 200 nF, the Primary current stays below 500 Amps and there is
breakout from the toroid.
So anyway I'm glad I tried it...



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