|[AMRadio] Seeking advice on "wires in trees"|
wa3vjb at yahoo.com
Wed Apr 29 10:06:44 EDT 2009
Bow and arrow have proven to be the best method for me in our woods.
Metal arrow is drilled at the bowstring-end, and eventually tie a run of 20# monofilament fishing line. The leading tip of the arrow is removed and replaced with a fishing weight, which then is epoxied and heat-shrunk. Spray the arrow with day-glow marking paint.
Compound bow can be cheap. Doesn't have to be a multi-pulley, expensive job. I use a 35# bow and have used the combination with the weighted arrow and monofilament to achieve dipole installations at 60-70 feet in height.
I endorse the use of marine rope to minimize weather deterioration. I prefer to use pulleys at both ends of a dipole or one in the center of an inverted vee. This allows me to easily raise and lower to trim the antenna to frequency, and to occasionally inspect the coax, since that takes a lot of flex in a dipole configuration.
Pick your branch, shoot your monofilament. Use that to then bring back your marine grade rope and pulley. The pulley should be a swivel type, marine grade or other weather-resistant, and the channel should match the size of rope. I use 3/8." Install a piece of old garden hose on the first five feet of the rope leading up to the pulley. This protects the tree.
Now pull the pulley rope up to the branch, bounce the hose over the branch, and allow yourself about a foot or two lateral distance from the pulley to the branch. As it goes up, keep the other two lengths untangled as they all go up to that branch. One end of the service rope becomes your end insulator, the other is how you'll raise and lower the antenna on that side.
Repeat for the other side.
Center supported inverted vee is the same deal, one pulley, two ropes, but you tie off the unstressed ends of the antenna without needing a lot of load mitigation. The pulley rope, sheathed with garden hose, stays in place, while the second rope raises and lowers the vee for trimming, coax inspection, etc.
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