Paul Koretko wrote:
>
> I am putting up a new M2 Rotor on a Rohn 25 tower to swing a Sommers
> XP708 antenna. I am using the Rohn bearing plate on top of the
> standard 25G section. I intend on mounting the rotor at the bottom of
> the first tower section down from the top. I plan on running a 2" OD
> mast from the rotor through the bearing and approximately 10 feet
> above the XP708 which I intend on placing on right above the bearing.
> I will be placing a Cushcraft AR270B at the very top of the mast above
> the beam.
>
> Here is the question: I have been trying to decide what kind of
> material I should use for the 2"OD mast. I have gotten prices for
> 4130 material 2"OD with a 1/8" wall thickness, and a carbon steel
> tubing 2"OD with a 7/32" wall thickness. The 4130 will cost about
> $7.95 per foot and the Carbon Steel will cost about $6.50 per foot.
>
> What is the strongest and best type of material of the 2
> possibilities? Are these prices about right for these products?
>
> Thank for the advise.
>
> Paul
> WA0BAG
These mast are all good but you might consider using 1-1/2" Schedule 80
pipe. It is quite a bit thicher than sch 40 pipe and uses a higher
grade of steel. It works well for a lot of people and is less
expensive. Another option is to find a soil testing company, their
drill rigs use 4350 semi stainless steel drill rods. When the ends of
the rods get bad they have to throw them out but they make fantastic
mast pipe with incredable strength. These drill rods come in many
diameters.
Gale
N8GS
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