I am still trying to decide if I can build a case sufficient for an engineer
to sign off guyed Rohn 45 of 70 ft carrying a Yagi of 25 sq ft cross section
in an area with a 70 mph wind requirement, no ice. The starting point is
that the Rohn guying diagrams show only a 15.9 sq ft capability. Several
folks on this reflector have steered me to the additional sq ft that could
be perhaps legitimately be added due to not using side panels. Others have
said, guy for 90 ft where the rating is 15.2 sq ft-the rating at 70 mph
would be (9/7)^2* 15.2. The arguments they have made seem reasonable, but
not conclusive, and I don't know if that would be enough to sway the signoff
guy. If you know of some supporting material for this argument I would
appreciate hearing.
A Rohn dealer sent me an email saying with guys or brackets within 10 ft of
the top the rating at 70 mph is 35 sq ft (lower guys or brackets required).
He pointed me to the bracket elevation table in a Rohn on-line catalog and
there it was as he said-35 sq ft for the bracketed tower.
But my tower is not going to be bracketed to the house. So far I have not
found an equivalent for a guyed tower. Does anyone on the reflector know
where this info could be found for a guyed tower? My Rohn catalog has
disappeared into the chaos of moving cartons, but once fairly recently I
found a huge pdf file containing the entire Rohn catalog from 20 years ago.
Does anyone know of a link to the complete catalog in a single file? It
seems to me that the on-line "modern" catalogs have links to various
information but are missing info in the complete catalog.
By the way, a couple of structural engineers have said they have analyses
that will verify Rohn 45 will meet my requirements and they will be glad to
put together a report for me for prices around $500. Seems pretty expensive
for a reprint, but I suppose it's the free market at its best. Does anyone
on the reflector have such an analysis?
Bob W2WG
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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