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Author Topic: extended double-zepp  (Read 932 times)
K5PSO
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Posts: 68




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« on: May 27, 2001, 07:05:00 PM »

I'm looking for comments from anyone who has used one of these, advice is appreciated. Is it a good dx-antenna? Mine will be approx. 35 feet up. I a thinking of using the K4TWJ design, on 20, with 42'3" per side and 7'3" ladderline to a 4:1 balun, then coax. Suggestions? Thanks and 73, Dan K5PSO
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AC5UP
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Posts: 3813




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« Reply #1 on: May 27, 2001, 07:38:38 PM »

You betcha' they work... At 35' you'll be good on 20 Meters or above and the no-tune bandwidth is generous. You can also cut an EDZ for 15 Meters that tunes 40 if you're careful when pruning and know when to stop.

I didn't use a 4:1 balun on mine, just a 1:1 no-loss choke (Reisert) balun. Take 1500 and divide that by the absolute lowest frequency (in MHz) of the band you're interested in. Cut a section of insulated 12ga THNN solid wire to that length. Fold it in half and cut it at the exact center. Divide 1210 by the band segment you're most interested in. That's the tip-to-tip length of the horizontal top section. The balance of the wire is arranged into a home-brew ladder line spaced 1 1/4" using 1/4" C-Pex plastic tubing and Ty-Raps. Attach a 1:1 current balun at the bottom and prune the vertical feeder until you see any hint of SWR at the lowest frequency of the band. You'll find the SWR curve rises steeply at the bottom end and very gently on the top side, so watch the bottom of the band when tuning.

EDZ's tend to be no-fuss, broadband, tolerant of nearby objects, and very efficient radiators. The only negative is that the 15 & 40 Meter combo is the only multi-band version. Otherwise, it's a mono-bander.

They make excellent add-a-band wires for those who always wanted to get something in the air for 17, 12 or 6 Meters and work well in an attic on 15 through 6. (they will tolerate having the ends zig-zagged to fit)
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LA1SJA
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Posts: 55




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« Reply #2 on: May 29, 2001, 12:25:53 PM »

Extended Zepps with ladderline are just great.
I have ended up with a more relaxed view of exact dimesions for Zepps.
If you can use a tuner and a 1:4 balun you may set youself free from having to cut them to any specific lengths, and they will still be true multiband antennas without any "difficult frequencies" that may follow from trying the black art of cutting tunerless/coil-less multiband antennas. In 9 out of 10 cases you end up fixing the problems of a zepp that is claimed to have magic dimensions with a tuner anyway. Just cut it so that it fits available space. Use any length of ladderline that is required. The tuner will fix the rest. Some observations; 2x43 feet or longer is ok for 7 to 28 MHz. If your tuner can live with high voltages you may strech it down to 1.8 MHz but at low efficiency. 2x 86 feet (2x26meters) works well from 1.8 to 28 MHz, especially as inverted V. 2 x 117 feet for 1.8 MHz if you have the space for it (When they get that long they will not be too good above 10 MHz though.). The higher up the better. Zig-zag through the garden if neccesary.
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