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RE: Even More DRSSTC numbers

Original poster: "Steve Conner" <steve.conner@xxxxxxxxxxx>

>Looks like the best i
>can do is K=1.57, vs the 1.7 figure typically seen, and thats at 70uS
>burst lengths (only 20" spark though).

That's on your little DRSSTC-3 though right? Small coils do seem to be less
efficient than big ones.

>One interesting thing is that the peak currents dropped lower as i >increased the burst length!

That's not really surprising since you were decreasing the AC input voltage
as you increased the burst length. Why did you do this, was it to keep a
constant spark length or something?

If you had kept the input voltage constant, I would have expected the peak
current to go up as you increased the burst length, or stay constant,
depending on the tuning and coupling.

>I'm pondering either converting the setup to a full >bridge, or altering the tank Z

This would be an interesting experiment sure enough. Like you say, halving
the tank Zo or doubling the drive voltage should have the same effect and
should roughly double the peak power. (halving the tank Zo would double the
peak current though and you're at 400A already)

No matter what the result of this experiment we will learn something
interesting about streamer loading. If the coil does not get any more
efficient then that suggests the toroid capacitance is the limiting factor.
Maybe the root cause of low performance in small coils, is that a small
toroid just doesn't have enough charge on tap to meet the demands of a
decent sized streamer. After all we know that a streamer grows by jumps
drawing large HF pulsed currents as it goes and these HF pulses can only
come from the toroid capacitance itself.

So I would suggest another experiment- leave the tank Zo constant, use the
same secondary, but add a ridiculously large toroid.

Steve C.