Posted: 1/28/2008 2:32:52 PM EDT
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I'm fixing to home brew a G5RV. I see lots of articles praising the properties of open wire feeder line. The data I see shows very little difference in the properties given different spacing. Have any of you home brewed open wire feed line? Is 6" too wide for spacing? I'm using 12 gauge bare copper and plan to use 1/2 inch pvc pipe for spreaders. The data says it needs to be about 34 feet. Any comments? Additionally, I'm looking at a Palstar Antenna Tuner. An AT1KP model. It has a 4:1 balun built into the balanced outputs. Is that a problem using OWFL? Thanks for the braintrust. |
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The spacing I usually see in open-wire feeders is either 2" or 3". I don't have any personal experience with it but the only thing to remember is that your impedance changes with spacing. I remember an article where someone was doing just what you are. He drilled his PVC pipe about 1 1/2" from the end and then split it diagonally, so that he could twist the pipe onto the wire. It seemed like a pretty clever way to make his ladder line. |
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If you get some of the older antenna books, or maybe even in the newer ARRL Antenna book, there is a section that talks about this. With the advent of very good ladder line, there has not been such a need. Your spacing and wire size to some extent, will dictate the impedance. I hope that you have one of the analyzers.. Open wire feeders are great, especially for long runs at QRP. -Corn |
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A little hint on making your own open wire feeder: To secure the spreaders to the wire, feed the wire through the PVC, then take a pair of needle nosed pliers and kink the wire inside the PVC. The spreader will stay in place and it looks clean. A frind of mine made his own feedline: wide spaced open wire stuff like you are talking about, and he thinks it is the greatest thing in the world (active ham for probably 40 years who has trid most everything out there). |
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If you are only running 34 feet to the antenna, I don't see the requirement for ladder line. If you are running over a hundred feet, it might be worth the trouble. The high impedence lines have low loss and are valued for this. For that short of a run, coax and a 1:1 balun at the feedpoint is pretty easy. Of course, this is coming from a ham who tried to build his own UHF duplexer out of 2 inch water pipe, so good luck on the ladder line. RS |
I've cut a bunch of 4.5"x 1/2"ID PVC pipe spreaders. I plan to drill a hole through each end, .25" from the ends, to feed the wire through and then kink it. Then I've got a hot glue gun to glue it in place. I bought a 500 ft spool of 12 gauge jacketed single strand for the feed line and the top runs. Also ordered a Palstar balanced wire antenna tunner. I'm doing the pee pee dance waiting on it to be delivered!! Range report to follow. 
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