Jim Lux wrote:
> Why can't you put up the BX? Talk to an engineer familiar with your local
> conditions, and they may agree with your assessment that caliche is
> comparable to concrete. The BX wants a base that is heavy and large enough
> that a) the downwind side doesn't sink into the soil and b) that the upwind
> side doesn't pull up. There's lots of potential concrete pads that can be
> created that are compatible with this. One common strategy is to drill 4
> round holes, one for each foot (you see this on HV Transmission towers).
The other reason is the BX has X-shaped braces instead of flat ones, and
no one wants to climb the thing because it is horrible to stand on!!
>> Since this will be done in an enclosed area of yard that is only 40x40
>> FT, the three guy pipes will be placed so that they are sunk 5 FT into
>> the ground and extend 5 FT above the ground. We want to use 4" oil well
>> drill pipe for this. We can find the pipe because any piece with a crack
>> has to be discarded and they go to scrap.
> Of course, that crack indicates a failure of the pipe, no? (unless you're
> talking about taking a 20 ft stick with a crack at one end and chopping a
> section out of the middle?)
True. The wall of the pipe is 3/4" thick and the cracks are hairline and
discovered by X-ray (thanks Halliburton), I was told. I have yet to
inspect one of these to find the facts. Might be bogus info.
> As you increase the tension on the guy (e.g. by bringing the anchor in
> closer to the tower base) you increase the compression load on the
> tower, perhaps above that which the mfr recommends. You also increase
> the load on the anchor, tending to pull it out of the soil. And, of
> course, the increased downforce on the tower tends to sink it into the
That is a very good point.
> An engineer can answer all these questions, tailored for your particular soil
> conditions, in about an hour or two. The couple hundred bucks for the
> engineer will be well spent (and you might find someone to do it free or for
> the proverbial "sixpack".. check the ARRL Volunteer Consulting Engineer lists)
Ok, I am convinced to hire an engineer first. Then, I will know what I
can put up, and what I can't.
I trust that a 25FT pole embedded 5' in the ground will be OK to support
an end of a dipole without the engineer's approval :-) (not to open
another can of worms)
>> Is there a free downloadable calculator to help with the angles of the
>> guys and design of the site? All advice will be welcome.
> Not one that I would trust....
> Jim, W6RMK
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