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Re: Isotropic secondary capacitance
From: Edward V. Phillips[SMTP:ed-at-alumni.caltech.edu]
Sent: Wednesday, September 10, 1997 3:33 PM
To: tesla-at-pupman-dot-com
Subject: Re: Isotropic secondary capacitance
"> If you measure the Fres of one of your coils, then measure its inductance,
> does this calculated value of Cdist agree with the value you would obtain
> by solving the Fres (equation for resonance) for capacitance?
Medhurst agrees with the resonance and lumped-L check I've done on
_all_ coils I've wound to well within 5%. (2% in a majority of cases).
In short, yes."
Similar results here verify Malcom's observation. One caution
is necessary, though. The coil must be well isolated from any conductors
which might add capacitance to ground. I measure coils with them up
on a stool, several feet from anything else. Bottom is fed through
make that fed from a source with low enough output impedance that
the voltage doesn't "dip" as the source is tuned through resonance.
Voltage is observed on a scope or meter, with the pickup being a
1" by 2" plate below the top of the stool.
Ed