I like to homebrew my projects to save money as well, but the thing that nobody
seems to consider is that a non-engineered tower installation (either a
standard installation that doesn't adhere to the tower manufacturer's specs or
a non-standard installation that wasn't blessed by an engineer) becomes a
potential liability issue. I'd bet that most home insurance carriers would
balk at paying off a liability claim if someone was injured as the result of
the failure of a non-compliant installation.
73,
Dave AB7E
------Original Mail------
From: "jimlux" <jimlux@earthlink.net>
To: "Tower and HF antenna construction topics." <towertalk@contesting.com>
Sent: Fri, 12 Feb 2010 09:19:52 -0800
Subject: Re: [TowerTalk] tower installation HG52SS
Michael Goins wrote:
> Guys, I'm needing some help here.
>
> I am installing a HG52SS about 16 miles north of San Antonio
>
> This location is where I plan to live the remainder of my life, so I
> want it right.
>
> My question is: Is this sufficient, considering the ground materials?
You're asking an engineering analysis kind of question. The tower is a
self supporting one, so it depends on the big chunk of concrete in the
ground and the physical extent of that mass to stay upright. (think of
it as if you were planting a telephone pole or a tent stake.. you have
20-25% of the pole underground, and the fact that the dirt doesn't want
to move is what keeps the pole upright, even if you push on it)
To a first order, is the mass of your proposed base comparable? Is the
physical size comparable? (e.g. a spherical ball of concrete weighing a
ton is a lot different than a long skinny bar of concrete, also weighing
a ton, when it comes to pushing it through the soil)
>
> An engineer is out of the questions as I am an average guy, teaching
> college for what often feels like minimum wage. I am also at least 16
> miles form the nearest possible engineer which would add to the cost
> factor.
Maybe it's different in Texas, but 16 miles doesn't seem like a huge
difficulty for an Engineer to travel. (unless it's 16 miles of burro
path or something). I wouldn't say that I've never charged mileage or
travel time to a client when I was doing the consultant thing, but,
heck, lots of people commute many times that distance in a day.
Does the college you teach at have an engineering department? Maybe you
could trade a dinner for a faculty member for some advice?
>
> Again, this is an amateur tower installation. The load will never be a
> lot as the tower is not rated for a lot of load. It cranks up and
> down, and I monitor the weather here, so it would be lowered when
> conditions suggested that it would be prudent.
>
> I could sure use some opinions.
You're sort of doing two things at once.. Wanting an engineered
installation because you're concerned about failure risk; and,
simultaneously, wanting to save some money.
Basically, you're potentially paying a few hundred bucks (on a tower
installation that's worth several thousand dollars, even if you didn't
actually pay that in cash) to make it easier to sleep at night (you
haven't mentioned whether there's local regulatory implications). Only
you can make that tradeoff.
Here's something else to consider if you bought it used: in general, the
older the tower is, the less it costs to buy it, but the more it's worth
paying something extra to have a knowledgeable person (e.g an Engineer)
look it, especially if you're doing something other than what the
instruction book says. (or if the book is 20-30 years old.. engineering
practices have changed over the years)
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