Hi Terry,
> Do you think it matters ... if the current transformer is
> located right near the base of the coil ...
The current transformer will be a toroid, so a fairly tight
magnetic circuit, but not perfect. Keeping it away from
the mag field of the system will reduce spurious response
via the CT's leakage field.
So I would move it away for that reason. Otherwise, not too
difficult to shield from discharges and electric field effects.
If running a ground plane/counterpoise, run the sec base wire
away under the GP, or use a coax.
But too long a wire and you have to account for the shunt C
of the wire to ground (thus bypassing the CT primary).
Others mentioned E-field probes. Easy to calibrate, and easy
to model too if you have a nice shape to the probe such as
a sphere, disc, or toroid. It may be preferable to operate
the E probe grounded and measure or record (via a CT or shunt)
the current flowing in that ground. Then your instruments are
more isolated.
Trouble with E probes is they respond to the field of the whole
system, not just the topload (which is the waveform you really
want to capture).
Seem to remember us discussing dividers a long time ago and
not coming up with any really great solution.
--
Paul Nicholson
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