delara newsDelaware Amateur Radio Association, Delaware OH VOL 37 NUMBER 2
Craig MIller W8CR
The End of My Rope
The best bang-for-the-buck antennas in use for amateur radio are simple wire antennas, dipoles most notably. Couple bucks of wire, some rope and two trees and you’re on the air beaming your robust voice or digital signals all over the world. If a dipole antenna is too boring for your taste, there’s a million other types of wire antennas that claim to be the Big DX antenna: G5RV, Carolina Windom, Extended Double Zepp. I’ve tried them all.Just like your furnace never breaks in the middle of the summer, car battery never dies in the garage on your way to meet your mother-n-law for lunch, a wire antenna never breaks in the middle of summer on a calm, clear, warm day. It’s always in the dead of winter when you notice the SWR needle slams over and bends against the pin and you can’t hear a thing on your radio. You look out the window at the snow flying horizontally past trying to get a view of your antenna you erected when your kid was still in middle school, ten years ago.“What could possibly have gone wrong?”Usually the rope you used to string up the antenna finally gave in to the abuse it has taken rubbing back-n-forth in the crotch of a tree limb over the months and years. Stuff happens. Nothing is permanent (except that tattoo with the name of the girl you dated just before you met your future wife – bad move).The last time I strung up a 40 meter dipole, I bought the really good rope in a 500’ spool from DX Engineering. The stuff isn’t cheap but it’s purported to be the greatest stuff out there for antennas. It’s double braided, Dacron/polyester construction, 770 pound tensile strength, UV and abrasion resistant. I’ll never have to work on this antenna again for the rest of my life!Well about 6 months later, one leg of the antenna broke where the tree was rubbing against the rope. No problem, I’ll just pulled down the antenna, check things out, replace the rope and try again. Well, it turns out the other leg of the antenna wouldn’t come out of the tree. The outer black sheath also abraded and the sheath bunched up in the fork of the tree, preventing me from pulling is down.I tug and tug until the antenna wire breaks from the insulator tied to the rope, now the only way to extricate the rope, and insulator, from the tree is to pull on the other end of the rope. As predicted, the insulator now is wedged in the same fork of the tree. I’m stuck. I have about 100’ of this fancy, high priced antenna support rope hung up high in the tree. No way to get it down without felling the 70’ tree.What good is this stuff if it’s still going to fail at the contact point with the tree and bunch up so I can’t get it down?Maybe I should just use cheap rope from now on. If it breaks, I’ll restring using more cheap rope. The problem is the contact with the tree. No matter how good the rope is, it will eventually fail unless you can eliminate the rubbing action as the tree sways in a breeze. I recently found 100’ lengths of cord at a store that’s rated at 275 pounds tensile strength. This stuff is a lot thinner but the 275 pound pulling strength should be more than adequate for a wire antenna (I’m not gonna rappel down a cliff with the stuff) and it’s cheap, $2.70 for 100’ – not bad! I bought 600’.This time, I’m going to incorporate a pully and weights to see if allowing the line to play out/in during winds will help prevent the chaffing. Once I got things strung back up, I found I only needed about 40 pounds of weight (coincidentally the exact mass of two shock absorbers I recently replace on my truck) to keep the antenna taunt. I’ll report back when things are laying back on the ground – hopefully not for a while.