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Re: [TowerTalk] Homebrew Crank-up

To: "Tower and HF antenna construction topics." <>
Subject: Re: [TowerTalk] Homebrew Crank-up
From: Steve Maki <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Sat, 27 Mar 2010 22:48:15 -0400
List-post: <">>
Kevin Normoyle wrote:

>> As mentioned the lower section would be large (33 inch face) tower  
>> with 3 inch diameter legs.  The top would either be 55G or 65G.  

> It doesn't matter whether you analyze the top section as if it started 
> on the ground or on top of something else.
> It's the same analysis. right?. (except higher wind higher)
> the first post said
> "about 75 feet of 55G or 65G that would telescope into about the same 
> length of larger tower (33 inch face, 3 inch legs),"
> Even chopping 15' off that for a joint, you're saying 60' of unsupported 
> 55g.
> I guess you could say you're designing for 0mph wind. The problem is you 
> want to design for close tolerances, so the top doesn't bang around a 
> lot in a slight wind. But if it bends, then the tight tolerances mean it 
> won't come down. So knowing whether the top section is going to bend 
> seems important.
> Maybe you're talking about a shorter length of 55g.

I'm going to take a wild guess here - Stan has a pretty good idea about 
what a length of 55G or 65G can handle unsupported, plans to retract it 
except for mild weather contest weekends, plans an install in a place 
where a failure wouldn't be catastrophic, and would like ideas about the 
best way roll a length of it in and out of a larger tower. It's just a 
wild guess mind you...

-Steve K8LX

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