[Elecraft] Charge build-up on antennas

[Karl]

Your idea of a shunting resistor across the antenna terminals (I'd do it at
the antenna insulator) of about 50K to 100K will do just fine.  Some folks
use r.f. chokes, but they are not as "broadbanded" as a 1-watt carbon
resistor of 50-100K.

Yes,  a one-watt resistor, at 50-100K will handle over a kilowatt of
transmitted power IF the VSWR at the feedpoint is reasonable.

A little known fact:   the water pouring from the shower head in your home
can produce as much as 15 kV of static electricity!  Now let's see.... where
do I connect that 100K resistor in my armpit to the shower stall?

Karl K - W8TIF
McKinney, Texas

----- Original Message ----- 
From: "Bob - AG5Q" <AG5Q@attbi.com>
To: <elecraft@mailman.qth.net>
Sent: Wednesday, May 21, 2003 5:03 PM
Subject: [Elecraft] Charge build-up on antennas


> During a rainstorm, how fast does charge build up on an antenna?
>  I suppose the area of the wires and tubing would affect this, as
> well as the amount of rain and wind. I'm wondering if a large resistor
across the antenna connector (say, 10K to 100K) would be able
> to discharge an antenna that is not connected to a rig or is a much
smaller resistance required (like a short circuit) to limit the
> voltage to no more than a few volts.
>
> I'm assuming just an ordinary rain storm and neglecting the effect of
lightning in the area.
> Several years ago I noticed enough charge building up on a 20 meter dipole
to jump across a small air gap of a ground switch that
> wasn't closed completely.  This occured during a light rain storm.
However, I didn't take any quantitative data at the time.
>
> This is a potential hazard to a rig if you connected an antenna without
shorting the connector terminals first, but would it  be
> enough to just put a resistor across the connector?
>
> 73/ Bob - AG5Q
>
>
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