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Re: [TowerTalk] Non-Conductive Mast Section

Subject: Re: [TowerTalk] Non-Conductive Mast Section
From: K8RI <>
Date: Fri, 09 Dec 2011 03:31:56 -0500
List-post: <">>
On 12/9/2011 2:06 AM, Jim Brown wrote:
> On 12/8/2011 9:23 PM, Keith Carter wrote:
>> The way I have done this for vertical yagis is to use two metal angle
>> brackets spaced about 2 to 3 feet apart off the side of the tower.
>> Then use a fiberglass pole about 4 feet long (available at most
>> hamfest as military antenna mast sections)
> Several guys have suggested some variation of this approach. It seems to
> make good sense to me, and is what I'll probably do.  What I'm looking
> for now is suggestions about those stand-off brackets.

You could do it as a swing arm mounted off the face of the tower. IE any 
side with two legs, rather than just one although the one would give you 
more rotation.
Variations of this can be used for one of two legs.   For one leg 
attachment the mount forms a right  triangle with the base at right 
angles to the tower.  The tower forms the vertical (up or down) part and 
the angle from the outer end of the base to the tower forms the 
hypotenuse.   The base and hypotenuse mount to the tower using u-bolts, 
or saddle clamps.  You could also use a piece of angle iron or flat 
plate maybe an 1.8" thick at this point.  You can adjust the triangle 
some so a pipe is either welded or bolted to the outer end of the base 
and junction of the hypotenuse.  The rotator mounts on this.  The top 
end of the mount(second mount) has a pipe attached to it for the 
insulated mast or rod.  Depending on the wind load a third triangle 
could be mounted just above the rotator to prevent flexing.  The antenna 
would mount roughly half way between the top and bottom mounts with the 
coax routed off the back end of the antenna and looped around to the 
tower below.  With a long boom antenna it's unlikely you will be able to 
mount it far enough from the tower to get much more than 60 to maybe 90 
degrees rotation, but at the limits the antenna elements would be so 
close to the tower they would interact with it.

Without being able to draw the mounts this is about the best explanation 
I can give.

I do have some drawing and drafting programs some where so I might be 
able to come up with something a bit more concrete and pictorially 
complete, but it might take a while.


Roger (K8RI)
> Many thanks to all who have contributed a bunch of good ideas.  This
> list is a great resource!
>    73, Jim K9YC
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