You missed the point of my question. You stated that a GDO
can be used
to find a series resonance. My understanding is that's not
correct.>>
You missed my point also.
We shouldn't apply a snip of fact to a complex system. If
we do we'll come up with silly things like magic glass in
3-500Z's, 5 watt resistors that hurt capacitor life, or
electronic grid trip circuits that need to be thrown away.
The "I can stick a GDO on a distributed circuit and tell
what the impedances are" thing is just another silly
oversimplification, like using a old slow spectum analyzer
to determine the frequency causing an arc while the arc is
inprogress.
A GDO detects loading of the coil in a self-excited
oscillator. It does not quantify Q, impeance, or anything
else. If I have an OPEN series circuit with a perfect single
coil and a single cap and no distributed impedances the
circuit has no resonance. There is nothing to detect. I
think this is what you are alluding to, and that is a
factual conclusion. Without a resonance there is nothing to
detect.
What if I put a 1000 ohm resistor from the open end of the
series resonant circuit to ground? What if I put a handful
of very small capacitors? What if that series component
combination connects to another component or seires of
impedances? If that system is a complex system of
distyributed capacitances and inductances the meter can show
dips that tell me nothing at all about resonance modes or
impedances.
It can detect a "good resonance" where the complex grid path
is series-resonant or low impedance, it can detect
meaningless resonances like a pin-to-pin socket loop, it can
detect other resonances coupled into the grid from another
element or other components.
What I am saying is it tells us nothing about the system way
up in the tube.
73 Tom
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