Topband: Fw: 25G insulators
Donald Chester
k4kyv at hotmail.com
Sat Aug 30 08:46:16 EDT 2003
>A full size 160 vertical will draw big arcs during thunderstorms. At NR5M
>they had to short the vertical to ground with an auto battery jumper cable.
Better still, install a heavy duty spark gap across the base insulator, and
adjust it a little beyond the point where it arcs over at your peak power
during wet weather. That's the way they do it at AM broadcast stations. I
use a similar arrangement with my quarter wave 25G tower, and after 20 years
the only major lightning damage I have received at my station, other than
some shattered guy wire insulators, was when I forgot and left my
professional quality rf step attenuator connected and the internal precision
resistors blew up like firecrackers (but I was relieved it was only the
attenuator and not the receiver).
As a further precaution I have a large silver plated military surplus knife
switch in series with the line that carries the rf to the base of the tower,
and I open it when the station is not in use.
Don K4KYV
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