[TowerTalk] yagi comments

[force12@interserv.com]

Good afternoon, Chris.

Thought I would make a note to you about your response. The comment about 
Force 12 using "much thinner tubing" needs to be clarified, because it is 
generally inaccurate.

The tubing wall thicknesses are set depending on the structural model and 
every individual antenna is done. This is more than 120 at the moment, so we 
have a lot of experience here.

On most 20 through 10 mtr standard 80 mph elements, the walls are always 
double at the center sections, then average .049". The tips is .035" to not 
only save weight, but to maintain the mass taper, along with the outside 
diameter taper. On "D" (100mph) and "H" (120 mph) models, the wall 
thicknesses vary from triple wall at the center sections, double wall for 
most of the element, then .049". On 40, 80 and 160 mtr elements, the wall 
thickness varies up to .250" and the diameters are up to 3".

The second thing is that we use 6061-T6 tubing, NOT 6063. This makes the 
slightly thinner 6061 as strong as the 6063, but has less weight.

This is why it is great to utilize a full structural model. One does not 
have to guess or speculate about anything. We look at every individual 
piece, the element as a full structure, each piece of the boom, the boom as 
a structure and the elements and boom as a full assembly.





Have a good day and 73,
			Tom, N6BT
			Force 12 Antennas and Systems
			(Home Page   http://www.QTH.com/force12 )



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