[TowerTalk] Birds and the Leaning Tower

[Jim Thomson]

Date: Tue, 02 Aug 2016 10:31:34 -0400
From: Dave Leisman <w8qwdave at casair.net>
To: <towertalk at contesting.com>
Subject: [TowerTalk] Birds and the Leaning Tower


Got a very different question for the group.  I have a couple of very large antennas, one a 3 element 40 meter yagi and the other a 3 
element full size 30 meter yagi.  My problem is the birds which hang around these antennas.  I realize the antennas are a great place 
for birds to land and scope out prey below, but the other day a rather large bird tried to land on the end of one of the elements of 
my 40 meter beam and bent it down almost to a 90 degree angle. Now I can either take the antenna down (no small job), fix it and re-
raise it, or I can hire a manlift (no small expense) and do it mid-air myself.  

Does anyone have any suggestions how I might keep the birds away from my antennas so I can avoid this kind of hassle in the future?

Thanks in advance.

Dave, W8QW


##  did the entire 40m ele rotate on the boom.... or is the tip permanently bent down 90 degs ?? 
If the tip is bent down permanently, the tip is not strong enough.  If designed right,  you should be able to load
the eles and tips with ice.  The worse that will happen is the tip will deflect straight down at a 90 deg angle. When the
ice falls off /melts, the tip will spring back up.   If the tips are made from something like .375 inch OD  x .035 wall,
replacing the  tips with .058 wall   should do the trick.   But you would also have to look at the next inboard section of
tubing as well.  By using thicker wall tubing /  and /or  doublers inserted into the weak sections, you can substantially 
increase the strength of an ele, without adding a lot of weight. 

## I noticed that birds sitting on the tips of els are not fazed in the least... when 1-2 kw cxr applied to the yagi.  One would
think with the extreme high RF voltages on the tips of a yagi, that  the birds would fly off, they dont.   Years ago, I had a 
204BA  sitting on wooden sawhorses..and applied a 600 w cxr to the yagi.   I could light up a florescent light tube full tilt,
when the 4 ft tube held parallel to either tip of the DE..and several inches away. 

##    http://www.k6jrf.com/k6jrf_BS_Repair.html    here  K6JRF  uses  bird spikes to get rid of the bird problem.
click on any of the pix to see a close up of what bird spikes look like.   he used em end to end, across his 75m rotary dipole.
End of problem.   It’s another option. 

Jim   VE7RF