I'll agree that grounding on a roof tower is much more difficult and
structurally, there's some work that must be paid attention too. But that
structural work is not any more difficult than building a rebar cage for a
free standing tower.
The grounding is more difficult, but you can do pretty well by running
several ground straps from the tower to ground. Not ideal, no but good
enough - likely. A lot of guys have their towers right next to their
houses. Either on the house or beside it, there's not going to be much
difference in a direct strike.
And finally, a roof tower, really doesn't have to go that far about the
roof. If one's house is 30 feet at the peak, then a 34 foot tower as in
this guy's case will put the antennas about 4 feet above the roof line. You
can do the same with the smallest of the Glenn Martin roof towers. Most
people have TV antennas higher on their roofs than what you could end up
with a ham antenna. And generally the TV antennas have crap for ESD
protection.
Yes, there are tradeoffs and common sense must be used.
73,
Jon
NA9D
on 1/16/03 7:43 AM, Roger Borowski at K9RB@bellsouth.net wrote:
> Jon, Top Quality Gin Pole kits can be obtained from www.w9iix.com for about
> 1/3 the $700 amount you quoted. I'd also be reluctant to recommend a roof
> mount tower as most people don't install these with proper mounting know how
> and reinforcement and also, more substantial, and the biggest reason, the
> structure is suspect to severe damage from a potential lightning strike.
> I've seen one house and one garage, both suffer severe fire damage from
> lightning hits to roof tower systems over the years. A serious consideration
> that should be mentioned when rooftop towers are suggested. Everything is a
> trade-off of some kind. Rooftop towers may be less expensive than a ground
> mounted tower, but there is no comparison where safety is concerned. I, for
> one, do not care to jeopardize health and well being of myself, my family
> and my home for some dollars and (questionably) somewhat less efforts. For
> safety, grounding techniques aside, antennas and towers have no place being
> attached to dwellings in any area where lightning is a possible
> consideration.
> 73, -=Rog-K9RB=-
-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)
Citizen of the People's Democratic Republik of Illinois
Life Member: ARRL, NRA
Member: AMSAT, DXCC
http://www.qsl.net/na9d <- Updated on 1/12/03!!!
"A life lived in fear is a life half lived."
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