Hi Eric,
I had a similar "problem" with rock just inches under the soil on my 5
acres here in Colorado. With more than a little trepidation, I decided
to install the tower base above ground by cementing rebar into holes
that I drilled into the rock. It's been up for 5 years with no problems
despite 90 mph winds. The tower is a US Tower TX-455with a SteppIR 4L
and 30/40 M add on at roughly 60 feet. You can see how I did it at:
http://www.wd0m.com
Click on Ham Radio, then Tower Project. I consulted with local
microwave tower installers who put them on mountaintops with nothing but
rock to use as a ground. Their suggestion was to use 50 foot lengths of
copper strips laid out on the ground to carry the lightning away from
the tower. I don't have a ground rod except at the SPG near the house.
They say it works well here in the Rocky Mountains.
I've had a hit, and, coupled with the SPG grounding system, everything
survived OK. My control cables and coax are simply placed on top of the
ground and run back to the house.
Please let me know if you have questions. Different sites will
certainly have different obstacles to overcome. Good luck with your
project!
73,
Joe
WDØM
> TT Gang,
>
>
> We have been considering moving from our little in town lot to the country
> side. One of the homes on our short list has about 2 acres of land but there
> is only a scant few inches of dirt and in some places no cover at all over
> top of what I can only call fractured rock. To me it looks like good old
> limestone and by fractured I mean it has small crevices that go into the
> ground every so often, with areas about, let say about the size of car
> parking spaces.
>
>
> To be honest, as of yet I have not checked with any tower manufacture or
> dealer yet, this will come too. I do however wish to ask those that have
> firsthand experience erecting self-support towers on rock, that would be
> both advantages and disadvantages. The main disadvantage I see is these is
> no simple way to install a ground system nor do I see a easy way to bury
> feed lines and control cables in the ground without.
>
>
> Though there is plenty of room for guyed towers I really would like to stay
> with self support. My one tower is a Trylon 72 ft which I was hoping to
> recycle at any new QTH we might move too and I remember Trylon having
> options for rock, just not sure how well they work. I have not decided if I
> will recycle my older Delhi second tower - yet.
>
>
> All ideas welcome?
>
>
>
> de Eric - VE3GSI
>
> ve3gsi@canada.com
>
>
>
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