Hi Guys,
This post is not timely but i keep seeing reference to this topic, that
suggests that
a number of hams do not understand the purpose of the ground system under
a tower.
This is not a verbatim quote but is close(from Polyphaser):
The ground system is necessary to disperse large numbers of electrons
over a wide
area in a very short period of time, while causing minimum rise in
potential of the tower
and radio equipment, and thus damage.
Polyphaser recommends a ground system be less that 5 ohms(ideally) and
no more
than 5-10 ohms in any case. Typically, 5 ohms cannot be achieved with a
few rods.
The thinking on the distance between rods is twice the distance between
rods that =
the length of the rod.. That means if you are using 10 ft. rods, two rods
should be spaced
20 ft. apart.
NOTE: The power company ground is useless to you as lightning
protection. But, in the
interest of keeping all grounds in your yard at the same
potential(National Electrical Code
dictates this, Polyphaser recommends it, ARRL Handbook agrees), your
tower grounding
should be tied to all your other grounds.
73 de Roy Lincoln WA4DOU Elm City, N.C.
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