Topband: Fw: 25G insulators

[Donald Chester]

>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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