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On Fri, 18 Jan 2008 12:36:01 -0800, "Juan M."
wrote: A problem seeking a solution. I live in a wooded area of the Pacific Northwest with dozens of fir trees of 100 ft or more in height that make wonderful supports for high dipoles and other wire antennas. These particular trees have very few limbs at anything below the 60 ft level so using a crossbow or slingshot for installation is not practical. I have been forced to employ a professional tree climber to install the eyebolts and halyards. Using this system, the antennas can be raised and lowered for maintenance or modification. This system works fine until our winter storms kick in. Often, during those storms, a tree will lose a limb or two and take the antenna down with it. I am then left with a halyard tied to an insulator 50 ft or more above the ground with no way to get the insulator back down short of hiring another costly climber. Does anyone have any solutions to this problem? 73, John AE7P I can't speak for your specific situation, but here is how I handled the similar situation. I used either a multi-band-parallel dipole (sometimes referred to as a fan dipole) or a 135 foot dipole fed with 300 ohm twin-lead. These antennas were raised about 100 feet or so into trees by mason's line which can be purchased at Walmart or most hardware or building supply stores. My first antenna was taken down by tree movement shortly after having put it up. After that, I created a 'fuse' mechanism that released the line if too much tension was placed on the antenna end. What I did was to pull the antenna up partially until the antenna was just above the ground. I wrapped the excess line around two nails I used as a make-shift cleat. Then I wrapped the string around a nail and mounted it into the bark of the tree. I did this several times a different intervals until the antenna was raised to a maximum height still providing for general tree movement in the wind. When an excess wind strikes, it removes one or more of the nails lowering the antenna without breaking the string, or if a limb hit the wire, the antenna was low enough for me to reach the end of the line and put it back up. disclaimer: I didn't really trust the mason line to work as well as it did. I typically replaced it every six months or so (as I replaced antennas this often, mostly in experimentation or for improvements.) While I still use it today, I don't recommend it for anyone wanting to put up a permanent antenna and just leave it alone for more than a year. Buck -- 73 for now Buck, N4PGW www.lumpuckeroo.com "Small - broadband - efficient: pick any two." |
#2
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Buck wrote:
I can't speak for your specific situation, but here is how I handled the similar situation. I used either a multi-band-parallel dipole (sometimes referred to as a fan dipole) or a 135 foot dipole fed with 300 ohm twin-lead. These antennas were raised about 100 feet or so into trees by mason's line which can be purchased at Walmart or most hardware or building supply stores. . . . While I still use it today, I don't recommend it for anyone wanting to put up a permanent antenna and just leave it alone for more than a year. I don't think it works equally well for all kinds of trees. For many years I've used nylon twine or mason's line for raising Field Day antennas. The trees here in the Pacific Northwest are of course mostly evergreens which have a lot of pitchy sap and in many varieties, fairly soft wood. An antenna with a fair amount of tension causes the line to dig into the wood in a very short period of time. And even after two days, the line can sometimes be hard to get down because of being seized in the pitchy slot it cuts in the wood. So while it's fine for a very short time temporary setup, I don't consider it viable for longer term installation in the kinds of trees we have here. Roy Lewallen, W7EL |
#3
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![]() "Roy Lewallen" wrote in message ... Buck wrote: I can't speak for your specific situation, but here is how I handled the similar situation. I used either a multi-band-parallel dipole (sometimes referred to as a fan dipole) or a 135 foot dipole fed with 300 ohm twin-lead. These antennas were raised about 100 feet or so into trees by mason's line which can be purchased at Walmart or most hardware or building supply stores. . . . While I still use it today, I don't recommend it for anyone wanting to put up a permanent antenna and just leave it alone for more than a year. I don't think it works equally well for all kinds of trees. For many years I've used nylon twine or mason's line for raising Field Day antennas. The trees here in the Pacific Northwest are of course mostly evergreens which have a lot of pitchy sap and in many varieties, fairly soft wood. An antenna with a fair amount of tension causes the line to dig into the wood in a very short period of time. And even after two days, the line can sometimes be hard to get down because of being seized in the pitchy slot it cuts in the wood. So while it's fine for a very short time temporary setup, I don't consider it viable for longer term installation in the kinds of trees we have here. Roy Lewallen, W7EL If it is going to be a either temporary or permanent you might want to use the first line up to hold a pulley, then run the antenna line thru the pulley. Another way is to run your line thru a couple thickness of plastic tubing positioning the tubing over the branch to keep the line from digging into the bark. Also, if you have a old spare bowling ball (don't laugh), either the 4lb (duckpin) or the 16lb (tenpin) they make great weights for the end of the lines instead of having to use a pail with cement for the weight with eyebolt. Most of the bowling balls are made from hard rubber - all you do is drill a hole and insert some epoxy glue or super glue in it and then screw-in an eyebolt type of screw! When the wind blows and the tree sways the antenna line should remain constant. Make sure that the line is about 3 - 5 ft above the ground when using a weighted system. 73 de Howard W3CQH |
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