[TowerTalk] Choice of aluminum

[K8RI]

On 10/14/2012 12:40 PM, Richard (Rick) Karlquist wrote:
> If you can possibly obtain 3" aluminum irrigation pipe in your area,
> you will be much happier with it and probably save a lot of money.
> Stiffness is proportional to the cube of the diameter, so you really
> need the 3 inch diameter.  You can't fix this problem by using
> thicker wall small diameter tubing, because the weight increases
> as fast as the wall thickness, so the stiffness to weight ratio,
> and thus sag, is constant at a given diameter.  Irrigation pipe is
> made of a cheaper alloy than 6061, and therefore will take a set
> more easily.  But again, the large diameter trumps alloy selection.
> The exception to this is the completely different philosophy used
> in the Titanex verticals, where they bend like a fishing pole and then
> spring back.


And what does this do to your signal at the DX station's location?
When I put up verticals made of tubing I guy them to keep them from 
moving around even when strength is not an issue.

I would think that the signal from a vertical would be particularly 
susceptible to the antennas angle moving around.

73

Roger (K8RI)


  The alloy they are made of seems to be unobtainium
> AFAIK.  Has anyone successfully purchased from Titanex recently?
>
> Rick N6RK
>
>
> On 10/13/2012 2:09 PM, Rudy Bakalov wrote:
>> I was wondering if anyone can help me select the right material for
>> full-size 80m verticals. My questions are as follows:
>>
>> 1) metalsupermarkets.com offers 6061-T6 aluminum, but not T8. Is there
>> a difference between T6 and T8 for my purpose?
>> 2) Should go for the 0.125 or 0.065 wall thickness?
>> 3) Is 1" tubing OK for the topmost segment? Too stiff for the wind at
>> 70'? Not strong enough?
>>
>>
>> I am aware that many ham stores offer 6061-T8 tubing, but I do want to
>> buy it local in VE3, close to my QTH, in 12' lengths (instead of 6')
>> and avoid shipping complications due to length or clearing customs.
>>
>> 73 Rudy N2WQ
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