[TowerTalk] 80m 4-square materials

[Joe Subich, W4TV]

I'd suggest 38' or 48' of the tower with a shorter "whip."  It still 
works with a single set of guys at 30 or 35' - the whip will be 
stronger (two 12' sections of tubing, double or triple walled if 
needed) and one can easily get the resonant frequency down to the 
bottom of the band.    

73, 

   ... Joe, W4TV 
 



> -----Original Message-----
> From: towertalk-bounces at contesting.com 
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Dennis OConnor
> Sent: Saturday, December 16, 2006 11:26 AM
> To: towertalk at contesting.com
> Subject: [TowerTalk] 80m 4-square materials
> 
> 
> My first thought is 3 sections of 20G tower guyed at the top 
> and setting on UHMW pads.  Then 3 sections of 10 foot long 
> schedule 40 aluminum pipe in decreasing diameters... You will 
> need to shim them to fit together with ~1/2 foot overlap and 
> have them MIG welded into a single 29 foot piece... If you 
> make the two step down diameters far enough apart you can 
> have a machine shop bore a sleeve to join each section 
> properly without fiddling with thin sheets of flashing, etc., 
> or with bending thicker pieces for shims.. Say 3" to 2" to 
> 1"... I'll let you look up the sizes and play with the ratios...
> There are other ways to shim without machining, using  
> rectangular tabs with bored holes and welding through the 
> holes... Homebuilt aircraft fabricators will know how or you 
> can call me and I'll explain...
> Here is one source for pipe schedules:
> http://www.easternmetal.com/products/pdfs/standards/aluminum-p
ipe-extrusions.pdf

Anyway, this will leave you roughly 58"-4" tall and shy of resonant and a
0.5" tip extension and/or capacity hat will walk them on to frequency...

denny / k8do

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