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Re: [TowerTalk] Rigid Steel Conduit as Mast?

To: Jim Brown <jim@audiosystemsgroup.com>
Subject: Re: [TowerTalk] Rigid Steel Conduit as Mast?
From: John Kemker <john@kemker.org>
Date: Fri, 05 Jun 2009 19:18:31 -0400
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
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.

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
>   
-- 
--JohnK
73 de W5NNH
10X 75371/M&M 117/SMIRK 6185/Six Club 285/TRA 2499/Norcross 228 F&AM




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