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[TowerTalk] homebrewing yagis

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Subject: [TowerTalk] homebrewing yagis
From: (Bill Wall)
Date: Tue, 07 Dec 1999 06:32:52 -0500
Hi Mark,
After building Yagi and Quad antennas since 1972,  I might be able to help. I
spliced many booms over the years. I am not the final word on this. BTW I hold a
ME degree. There are many points to consider. At 36' or longer I would use 3" x
.120 Alcoa 6061-6511 drawn or extruded seamless tube. The splices should be 36"
long and 18" overlap inside of 3" boom.I use  3/16" or 1/4" aluminum pop rivets 
on each side to join boom tubing sections The boom should have a T-truss with 4
non-conductive cables. The splice material is rated aircraft, but it misses
telescoping by about .030.
This requires careful machining. The fit should not be not over .005. If you use
2" od boom material, the instructions will be the same. Depending on the weather
region, I would talk to friends in your area an obtain a good idea on past 
ice and snow. The prices on the materials will not be to far apart. I am not
familiar with what boom size you have, but the boom to mast and element plates,
possibly could be re-drilled. I am sure many amateurs have used far less HD
construction, but I have seen many of these on the tower broken in half or on 
ground. Call me if you want to talk about any of this.
                                                     Bill Wall   Antenna Mart
Quads wrote:

> For the folks that are constructing thier own yagis:  What is the proper way
> to make booms longer than the available tubing lengths.  Specifically, if I
> wanted to build one of Nathan's 36 foot 15M OWA beams what is the best way to
> construct the boom? I assume some sort of splice joint using a piece of
> tubing one size down and placed internally to form an overlapped joint.  Not
> sure how to properly phrase that, or what sizes to use to get a nice
> "nesting" with proper strength...  Also curious where folks are obtaining
> thier aluminium tubing for booms and elements.
> Cheers,
> Mark
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