In a message dated 96-12-02 09:59:34 EST, you write:
>I am erecting a quad antenna at the top of a Rohn 45, tilt over tower. To
>clear the top guy wires, I need to extend the mast some 6-7 feet above the
>top of the tower. The mast I intended to use is a Rohn M200, which is 2"
>outside diameter with a 16 ga. wall (.065). It appears to be mechical steel
>tubing, low carbon, electric welded (seam visible inside). According to the
>specification books at hand, it would be either hot rolled or cold rolled,
>but since it is galvanized, there is no way of even guessing. This is tubing
>designed for mast service, not conduit or pipe.
>Question: Is this mast adequate for 6 sq feet (35#) of antenna, 7 ft above
>the thrust bearing? Location is north Florida, Wakulla cty, about 15 miles
>from the Gulf of Mexico.
Hi, Ink --
You want the bad news or the good news first?
The bad news is that you are in a 100 MPH TIA-222 wind zone AND within
100 miles of hurrican oceanline so you need to use 100 MPH values for your
calculations at the minimum.
Eight square feet of antenna load six feet above the top of tower with
100 MPH winds exerts a force approximately 79,500 psi on the mast. I think
the mast you described is the same one sold by Texas Towers. If so, it is
rated at 87,000 psi. The good news is that this mast should be okay
according to the aforementioned assumptions and calculations.
Congratulations for doing your homework before embarking on this course.
73, Steve K7LXC
TOWER TECH -- professional tower supplies and services for amateurs
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Administrative requests: towertalk-REQUEST@contesting.com
Sponsored by Akorn Access, Inc & KM9P