[TowerTalk] Projected area of Hy-Gain beams

[Roger]

I was able to find a Rohn catalog dated Apr 1993 (although the inside cover
said 1991).  It looks like the numbers in the ovals should be used, as
these specify "allowable projected area (sq. ft.) for round member
antennas".   I only see guying diagrams for 70, 90 and 110 mph, though.
These tower designs are in accordance with ANSI/EIA-222-E-1991.  The TH7DX
at 11.5 sq. ft. projected area should be useable on guyed Rohn 25G, heights
40'-190', at 70 mph (13.0-18.4 sq. ft. allowable).  The TH7DX at 11.5 sq.
ft. is too much, however, for guyed Rohn 25G with 90 mph or 110 mph basic
wind speed.

The TH7DX at 11.5 sq. ft. projected area should be useable on guyed Rohn
45G, heights 40'-180', at 70 mph basic wind speed (11.8-18.8 sq. ft.
allowable). The TH7DX at 11.5 sq. ft. projected area should also be useable
on guyed Rohn 45G, heights 40'-160', at 90 mph (11.5-18.0 sq. ft.
allowable).  The TH7DX at 11.5 sq. ft. is too much, however, for guyed Rohn
45G with 110 mph basic wind speed (5.8-10.8 sq. ft. allowable).

The above numbers assume "no ice".  The basic wind speed for your county is
listed in EIA/TIA -222-D,E,F.  Steve K7LXC is sending me a more recent Rohn
catalog, so I can see if anything has changed wrt 222-F.

73 Roger WB0DGF
Telex Communications, Inc.
http://www.hy-gain.com



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