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Old July 8th 06, 06:08 PM posted to rec.radio.amateur.antenna
chuck chuck is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 9
Default E-field probe question

Richard Clark wrote:
On Sat, 08 Jul 2006 09:09:02 -0700, Richard Clark
wrote:

A 10 Meg Ohm meter would take 10
ms to discharge in comparison to 0.1 µs to recharge.


This was rather a hip-shot guesstimate where I put the cap on the
wrong side of the isolation line's resistance. Anyway, there's still
a significant charge/discharge ratio that isolates the meter.

On the other hand, having called it a clamping circuit was a stretch
too. It is in fact a rather sloppy design in that regard (it is self
discharging) but this is not to say it lacks its intended utility.

73's
Richard Clark, KB7QHC


Thanks for the info, Richard.

What I was looking for was information
on the charging part of the circuit. It
is not clear to me how or why the 1.8 pF
should recharge from the E-field in 0.1 uS.


The 0.1 uS time constant suggests a 5.6
megohm resistance in the charging
circuit. From where does that resistance
arise?

Put differently, what limits the rate at
which energy can be extracted from an
E-field through a capacitance of 1.8 pF?



Thanks.

Chuck


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