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Re: 3/4 wavelength secondaries
Question: Why the interest in free-space wirelength?
There have been a lot of listings here lately in
which it appears that the author thinks there is something
"magic" about having the coil operate near the free-space
quarter-wave resonant frequency of the winding. I can't see
what difference this really makes, as long as the coil is
excited at the correct resonant frequency as determined by
self and lumped (top terminal) capacitance. Am I missing
something?
One other point. Although I don't remember seeing
it expressed explicitly, the effects of a top toroid are
at least twofold:
1. The L/C ratio of the secondary is lowered, reducing its
surge impedance and hence the loss of Q for a given power
lost in discharge. Seems to me this should increase the current
when the discharge starts.
2. The breakdown voltage is increased, increasing the formation
of the streamers which finally carry current when breakdown
occurs. In the case of one of my small coils, this effect takes
seconds.
Any comments from the
"Richard's"
or anyone else?
Ed Phillips