[TowerTalk] Lightning protection

[Jim Lux]

On 7/8/13 7:21 AM, Pete Smith N4ZR wrote:
> I'll take those odds, and repeat - unless you are prepared to spend
> totally disproportionate amounts of money, or have the EE smarts to do
> it yourself, and the physical circumstancesto do everything optimally,
> you are begging far more hurt by staying connected.
>
> For every lightning hit 10 miles from a storm, there are probably a
> thousand that are well forewarned.  If you're looking to protect the
> Space Shuttle, that's one, thing, but...
>


I think, though, that the level of EE smarts required isn't all that 
high, at least for the builder.  What we need is something comparable to 
the Motorola and FAA docs (which are based, for the most part, on good 
engineering) but which is oriented and engineered towards the radio 
amateur.  A set of recommendations, based on science and well understood 
engineering, that is applicable.

We're different than a land mobile installation or a control tower. 
Maybe the challenge is that we haven't adequately described exactly what 
that difference is, so that the engineering process can be done.


There's plenty of anecdote out there. And there's plenty of R56 and FAA 
manual inspired ham installations out there.  The real question is, what 
parts of those 24/7 type installations aren't really needed.  There's an 
awful lot of "I built X, and it works for me", which as far as lightning 
protection goes is in the same category as "worked 100 countries DX" is 
for antenna design.


In the non-hobby world, recommendations like this get produced by 
putting up proposals, letting knowledgeable folks shoot at them, 
grinding through the cost/benefit analysis and documenting that analysis 
so that subsequent users can make the trades for themselves, etc. 
Sometimes, there's some experimental data needed. It's a slow process. 
Look how long it's taken for vertical radial field design to move away 
from the AM broadcast Brown, Lewis, Epstein (BLE) paper based 
approaches. Lots of analysis, lots of test data from folks like Rudy, 
N6LF, etc.

(In many ways, the radial issue is similar to the lightning issue.  The 
original BLE goal was to come up with something that could be used in a 
cookbook way and always meet the FCC performance requirements. It wasn't 
necessarily intended to optimize the length of the radials, the diameter 
of the conductors, or minimize cost of copper or labor.. It was was a 
system engineering thing: do this, and you don't have to spend the money 
on field proof of performance tests for a non-directional installation)




A definite complicating factor for the ham world is that hams have a 
penchant for changing their equipment configuration much more 
frequently, and they also use an amazingly wide variety of equipment, 
not all of which requires the same transient suppression techniques. In 
fact, (although I don't know of any examples), I'd bet that there are 
cases where a transient suppression technique for equipment A is 
actually the exact wrong thing to do for equipment B.

Maybe that's why one needs the individualized EE smarts?