In a message dated 98-08-24 12:46:16 EDT, W3SB@aol.com writes:
<< I am contemplating taking down my 10-year old 50 ft Rohn 25G tower and
replacing it with 70 ft of Rohn 45G. My reasons are twofold: 1) get the
Cushcraft A4 up higher and 2) stack a dualbander for 18 and 24 MHz above the
A4 (probably an A3WS). I don't want to go through the process of taking out
the existing tower base (short section of 25G in 4 ft of concrete) and am
thinking of using the 45G base plate fastened to the concrete base (with the
25G stubs cut off) with Hilti bolts. The tower would be guyed in 2 places -
one at 35 ft and the other at the 70 ft level. Does this make sense or
should
I pursue another option? I don't like the idea of stacking antennas on 25G.
>>
Why not? LeHigh County is a 70 MPH windspeed zone which is the lowest
they give. It's within 100 miles of hurricane oceanline so you might want to
build to 80 MPH spec or so. At 70 MPH, the 25G is rated at 16.2 sq.ft. - more
than enough for your proposed installation. I estimate at 80 MPH it'll take
12-13 sq.ft. - still more than adequate.
The 25G uses a CB1 base and the 45G uses a CB2 base. As long as your
base meets the minimum spec for 45G, I'd re-use it. They both use the 4A
anchor blocks.
Cheers, Steve K7LXC
http://www.championradio.com
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