Jerry,
I'm not a structural engineer, but here are a few observations. Notice
that in all cases Rohn specifies the top guy at 9' below the top of the
tower. I don't know if they mean a 10' section or an 8' section like
you have, but if it is 10', that implies that the uppermost guy is
attached to the top section of the tower. I think that is what they
mean, as it provides a downward force on the top section, which puts
the whole tower in compression, whereas if you guy it at 61', the top
section is relying only on its weight and that of the antennas to
provide the compressive force keeping it attached to the rest of the
tower.
I would suggest that you put the top guy about 1' up from the bottom of
the top section (65') and if you later add more sections, locate the
middle guy at 61' at that time.
I don't see any problem with locating the guy anchors at 80' vs. 56',
as this would still provide a hefty downward force on the tower while
providing a greater side preload, which I would consider to be more
critical.
73,
Bob, N7XY
--
Bob Nielsen, N7XY nielsen@oz.net
Bainbridge Island, WA http://www.oz.net/~nielsen
IOTA NA-065, USI WA-028S
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