MFJ-868 SWR/Wattmeter
Dave Platt wrote:
In article ,
Jim Lux wrote:
Well.. Consider a 20 meter long wire hanging 10 meters above the
ground (half a 80m dipole) so now you're talking tens of pA, 100 Meg
isolation isn't hard to get with clean insulators. That 20 m wire is
like a 850 pF capacitor. If assume, say, 25 pA charging current, you
get a volt every 42 seconds. After half an hour or so, you're up to 40
volts or so..
Granted it's not a lot of Joules.. (heck, probably not even a microjoule)..
So fair weather charging isn't likely to kill your MFJ..
Back to the dust/rain/induction charging, which can certainly get the
levels needed.
I've observed clear-air charge on a TV antenna (about 30' above ground
level) which was sufficient to create a visible spark when I touched
the center connector of the coax to a grounded static-drain block.
No rain at the time, no appreciable amount of dust (SF Bay area)...
just clear air with a mild breeze.
Were there any elevators nearby?
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