[TowerTalk] Lightning Protection Question

[Jim Brown]

On Tue, 14 Sep 2010 05:25:41 -0700, Jim Thomson wrote:

> Now whether the super duper, type 31 cookbook
>5 k+ ohm balun 

It is NOT A BALUN, it is a CHOKE.

>will impede the lightning is debatable.  

It will act like any other impedance in series with a discharge path -- 
cause lightning to look for a lower impedance path to earth, perhaps 
arcing to that alternate path or across the choke, dividing between that 
lower impedance path and the choke, and the voltage across the choke 
will produce heat in the choke. The impedance we're talking about here 
is the impedance at the frequency of the lightning energy, which IEEE 
data says has a broad peak around 1 MHz, extending a couple of octaves 
on either side. (An octave is a 2:1 frequency ratio). 

73, Jim K9YC