[TowerTalk] from towers to shack

[Jim Lux]

On 12/8/13 8:46 PM, Joe Subich, W4TV wrote:
>
>> I think as a practical matter, whatever transient suppression you do
>> at the entrance to the shack is going to be the same whether the
>> cables are laying on the ground, suspended 10 feet off the ground,
>> or buried a couple feet deep.
>
> Not if the cables are coming off the tower 10 - 15' high unless one
> has a grounded metallic "cable bridge" above the cables and connects
> the cable shields to the bridge/tower where they leave the tower.
>
> With cables exiting the tower some distance above ground, the lightning
> protection at the shack entrance will be much more critical.
>
>


But what would you do differently, transient protection wise?

Consider a direct strike to the tower?  The cables being above or below 
ground don't materially change the voltage waveform, at least as 
selection of the suppression devices are concerned: it's kilovolts you 
need to deal with.

A strike right to the cables? Is that particularly likely, given that 
there's a tall tower and a not as tall house next to it?

Conventional transient suppression techniques work for phone and power 
lines, which run above ground for miles.