[TowerTalk] Thoughts on towers suitable for my difficult location?

[Jim Lux]

On 10/23/13 1:38 PM, Larry Loen wrote:
> I agree with you, but to play devil's advocate a bit, maybe you plan for
> something that basically doesn't survive.

Yes, that's actually *my* preferred approach.  Determine what the 
acceptable failures are, and design with that in mind.


>
> Suppose you have a TV push up mast style design that is guyed decently.
> You put a two element quad on it or a small Yagi and only go up 43 feet.
> KY6R proved that even living in a big bowl in California, you can make
> Honor Roll with such a setup.  They key is a very light windload.  You
> don't go all out.  Say, a quad or a two element monobander.

And if that lightweight mast and antenna DOES come crashing down into 
your backyard.. there's no significant damage.

I think that's really the key: Most hams don't have a 24/7 availability 
requirement (compared to, say, FAA control towers or public safety). 
They can tolerate substantial failures, whether by the antenna elements 
breaking off, the tower bending, lightning evaporating the feedline, or 
whatever.

>
> So, maybe you just make sure it can't fall on anything interesting and
> build simple??
>
> Me, I'd go for the big tower with the (engineered) deeper hole.  But, if
> you have the space and you don't have to worry about it falling on
> someone, maybe you plan for something inexpensive that you can simply
> replace.  It would also be collapsible in the event of a hurricane as
> well.  The big worry would be unplanned storms or maybe being out of
> town when the hurricane blows in quickly.

Rapid stow is, I think, more of a peace of mind, than a valid mitigation 
of the risk.  As you note, what if the tower is extended, and you can't 
retract under load.

here's an example: If had a neighbor putting up one of those 150 foot 
telescoping contraptions and she claimed that in the event of a high 
wind, she'd retract it to 30 feet, so it couldn't fall on my house, 
mitigating the risk of her 150 foot tower coming through my roof.

I'd want to see an awful lot of analysis and testing showing that he 
could retract it fast enough, under all conditions.  It would be likely 
cheaper  to drill a 50 foot deep pier and put a cellphone tower in his 
backyard, engineered to withstand the highest wind speed continuously.

The extending mast, though potentially does have aesthetic advantages. 
So it might be worth it for my neighbor to spend the extra time and 
money and complexity.

But "I'll crank it down if the wind comes up" scenario is pretty much 
the same as "I'll disconnect the feed lines when I hear thunder".  They 
protect against some fraction of the failures, but not all.

Maybe the take home is that it's more "reduce the chance of breaking 
equipment" than "safety of life and property"