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Re: [TowerTalk] Arboreal non-wire yagis

Subject: Re: [TowerTalk] Arboreal non-wire yagis
Date: Fri, 28 Mar 2008 10:56:14 EDT
List-post: <">>
In a message dated 3/26/2008 9:02:13 A.M. Pacific Daylight Time, writes:

>  On my 1 acre lot, between the "front  yard," the house  and driveway, and 
I'm kinda outta room for  more  towers, but I do have lots of "vacant" trees 
near the property   perimeter.

>  Please share your success stories with how to  mount a yagi  on the trunk 
of a 
tree.  I'm
looking to  probably fix these in one  direction, so no rotation need be  

>  The main thing is how  to attach the  boom of the yagi to the trunk of the 
tree.  If you  have
any  photos, I'd love to see them.  If you've got a "tram" type  system,  
I'd REALLY like
to see that!

 Hiya, Doug --
    To rotate a yagi in a tree, you'll need to top  it. I don't know if 
you'll have to do that if they're fixed. If it's  topped, it is easier to 
since you have more open space for antenna  maneuvering and installing. 
    I use a piece of 1.5" galvanized water pipe (1.9"  OD) about 4-5 feet 
long when mounting an antenna above the top of a topped  tree. Weld a flat 
horizontal piece near the top so it looks like a cross.  The horizontal piece 
the mast from torquing back and forth. Bend the flat  piece so it touches the 
tree. There should be a foot or so above the flat piece  that extends above 
the top of the tree. 
    Drill a hole in each end of the flat piece along  with 3-4 holes in the 
pipe. Use 1/2" lag screws to attach the pipe to the tree.  While normally at 
this point I'd install a rotator (why don't you do that?) in a  mast-mounted 
configuration, feel free to bolt the antenna to the naked pipe. 
    You need to use a tramline to get the antenna up  there. There has to be 
a clear alley from the ground launch point to the mast at  the top of the tree 
so you'll probably need to do some pruning to clear the  branches. 
    The key - besides the tramline - is the tagline.  Tie it to the middle of 
the boom (so you can untie it when you're done) and then  wrap  it around the 
element closest to the middle of the boom 3-4 times and  then tape it loosely 
towards the end of the element. Choose a spot where you can  pull down on the 
tagline without causing any damage to the element. What you  need to do is to 
pull the elements almost vertical as the antenna reaches the  branches. That 
way the elements will miss the branches and when you let go of  the tagline as 
the antenna arrives at the top of the tree, the antenna will  level itself 
horizontally above the limbs. When the antenna arrives, untie the  tagline and 
have someone on the ground pull it thru the tape. It's easy and it  works every 
time.  (BTW as you're preparing the treetop, leave as many  branches as you 
can as high as you can. Feel free to do enough pruning to get  the antenna 
installed but if you trim too many branches at the top, there won't  be any sap 
drawn up to the top of the tree and it'll die at the top and start  rotting.)
    I use big nails into the trunk for coax  attachments. I use tie wraps to 
attach the cables to the nails. Don't put  anything around branches - that'll 
kill them. 
    Antennas in trees work like a bomb since there is  no metallic 
interaction - the antennas are electrically floating in space!
Cheers & GL, 
Steve      K7LXC

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