John Kemker wrote:
> So, for those of us who are in the process of tower-planning, what
> should we order from the local "metals supermarket" type of supplier to
> use for a 20 ft. mast to hold an HF tribander and a 6m beam?
>
> (Calculated wind load is 6 ft^2 for the tribander and 3 ft^2 for the 6m
> for 9 ft^2 total wind load from the antennas ONLY.)
>
> DeKalb County, Georgia is a 90mph county and I've specced everything out
> so far to 110mph ratings for the tower.
>
> I've found seamless steel tubing, 1/8" walls, non-galvanized, but am
> concerned with how to protect the interior from corrosion if it's not
> hot-dip galvanized? I can "cold-galvanize" the outside, but the
> interior is a different matter.
>
After a thorough cleaning, I cap the one end (often with nothing more
than sheet plastic and tape) , pour in about a pint to a quart of
Rustoleum., cap the other end and then roll it while tipping the ends up
and down to thoroughly coat the inside. It's still working after 6
years, OTOH it's no where near as good as hot dipped galvanizing, nor
will it last as long..
If the metal is thoroughly cleaned and etched I'd prefer a two part
Acrylic or Epoxy paint to the Rustoleum.
73
Roger (K8RI)
> Jim Brown wrote:
>
>> On Fri, 05 Jun 2009 18:52:50 -0400, Roger (K8RI) wrote:
>>
>>
>>
>>> There are two types of rigid steel conduit. The one is like schedule 40
>>> pipe and the other (EMT) is thin wall.
>>>
>>>
>> Clarification: Actually, there are three thicknesses of steel conduit
>> commonly used in North America. In the trade, they are designated "Rigid
>> Steel Conduit," "Intermediate Metal Conduit," and Electrical Metallic
>> Tubing. Wall thicknesses varies with conduit size, and for these 1.5-inch
>> nominal conduits are are 0.138 in, 0.09 in, and 0.065 in respectively. I'm
>> talking about using a 10 ft length of "Rigid Steel Conduit," which is 1.9
>> inch o.d., with only a 3-el SteppIR at the top (which is relatively small
>> and light weight).
>>
>> 73,
>>
>> Jim K9YC
>>
>>
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