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"Secondary" controversy
I'll add my 2 cents' worth: Exciting the bottom of my secondary at
primary resonance from a sine-burst generator, I find exactly the same
behavior as when it is excited similarly from my MOSFET-driven untuned
primary: Rise of top voltage (viewed via a 10:1 scope probe with no
toroid present) to 90% amplitude in about 22 cycles & exactly the
behavior one would expect at & subsequent to the 1st cycle--smoothly
rising from 0V & assuming a 90 deg. phase lag vs. the bottom voltage. I
believe that shows it's behaving like a (highly-loaded) 1/4-wave antenna
(tho I'm no expert on that).
Except...this is rather interesting, where primary resonance = 95 KHz:
I attach a 2nd 10:1 probe about 1/2 way up & note the following:
F, KHz 95 148 185 249 425 516
Top V:Mid V 2:1 1:2 8:1 1:1.5
Top Mid
min. min.
Top:F phase -90 180 +90 -90 +90
Mid:F phase -90 -90 >+90 +90
I don't quite know what to make of all that--except that, for practical
purposes, my t.c. runs only at the primary resonance & it behaves there
just as I'd expect, excited as it is with a square-wave burst.
Perhaps some of those odd overtones get unduly excited when all you
spark-gap people clobber your secondaries with God knows what, as you
generally do!
Ken Herrick
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