David L. Thompson, K4JRB, said:
>I have a number of posts on this type of tower over the past year. The issue
>seems to be the size of antenna with Rohn specs limiting the boom to 10 feet.
>The BX/HDBX tower is nearly 50 years old in design. The 10 foot boom length
>is a recent restriction based upon problems Rohn customers have reported.
>Rohn, being very conservative, decided that the 10 foot limit would solve
>the problems..and the problems are mainly with the top section twisting!
I looked into my Rohn catalog archives and the oldest catalog I could lay my
hands on that had BX tower in it was dated May 1977. The 10 foot limit was
in effect then, just as it is now. So that is at LEAST 21 years. I would
not call that a recent restriction.
>The HD version was made originally to WRL (Leo) specs for his Globe Spire.
>Read those old catalogs...there is no restriction on boom length!
I guess I don't have an old enough catalog. So, Dave, are you saying if you
can find an old enough catalog, or perhaps an old enough BX tower, you can
use it safely with a long boom . . . ?
I think my oldest Rohn catalog (1969) is currently on loan to K7LXC so I
can't look in it. I'm not sure that one has BX in it. Maybe Steve will
check for us. It is the thick one with the green cover, Steve.
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