[TowerTalk] iron pipe "lightning chokes"

[GALE STEWARD]

I recall seeing this iron pipe "choke" written about
in an article in HR (?) years ago. As I recall, the
author explained it as "adding a shorted turn" around
the feedline. I'm not sure how that would add to any
reduction of induced current from a lightning strike.
That's the way it was explained at the time. I could
dig the article out of my files if anyone is
interested.

Gee, it's already February so I guess I have to start
thinking about lightning again soon!

73, Stew K3ND


> 
> There is a transformer effect that would be the same
> mechanisim that occurs in a "shielded" loop. Current
> on
> conductors INSIDE the conduit would induce an
> opposing
> potential on the conduit inner wall, and that would
> cause a
> parallel flowing current on the outer surface of the
> conduit. Same thing that happens in concentric RF
> conductors
> used in transformers as well as coaxial cables.
> 
> 
> True enough. Except the magnetic effects of a
> non-isolated
> iron sheeth aren't what people seem to be thinking.
> At
> higher frequencies (much above DC) the fact the
> conduit
> isn't laminated or made from very tiny insulated
> iron
> particles nulls any magnetic effects, other than an
> increase
> in resistance obvious in skin depth formulas.
> 
> I don't understand why people think iron means
> increased
> inductance for alternating or rapidly changing
> fields, yet
> they gon out and buy powdered iron for inductors and
> laminated transformers for power frequencies.
> 

> 
> Not significantly different than a copper or
> aluminum pipe
> would.
> 
> 73 Tom
> 
> _______________________________________________
> 
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