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Author Topic: 20 meter extended double zepp  (Read 1597 times)
K5PSO
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Posts: 68




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« on: February 24, 2004, 09:24:37 PM »

I am planning an EDZ for a center frequency of 14.2 and I'm seeking a design equation to compute length. Any recommendations? Thanks & 73 Dan K5PSO
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KG4YWS
Member

Posts: 18




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« Reply #1 on: February 24, 2004, 10:18:03 PM »

Dan:

I looked the EDZ up in the ARRL Antenna Book (19th Edition) and the length for each of the two (dipole) elements is equal to 0.64 x wavelength.  The EDZ is normally fed with ladderline (balanced) type conductor.  At 14.200 MHz, each element would be approximately 21 feet in length.  Good luck.

73's,

David, KG4YWS
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N5NAE
Member

Posts: 14




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« Reply #2 on: February 24, 2004, 10:46:23 PM »

Mine has a total length of ~85 feet and works very well. It is quite broad as far as tuning goes and is fed with 450 ohm ladder line to a tuner w/4:1 balun.

I am also able to tune it to other bands using the external tuner. (Your results may vary.)

Take care..
Bob...
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W8JI
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Posts: 9296


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« Reply #3 on: February 25, 2004, 07:24:28 AM »

The correct length for twenty is about 80 feet or so overall. Not 21 feet per side (42 overall).

Make it just like a dipole but feed it with ladder line. You can cut the ladder line feeder to about 1/8th wl and feed the ladder line direct with coax. Trim the length of the ladder line for lowest SWR.

In that case the ladder line would be a Q section and cancel the reactance and transform the impedance to a reasoable value for coaxial line.

Or feed it with a tuner and use almost any length ladder line that makes the tuner "happy"!

73 Tom

 
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KZ1X
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Posts: 3228




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« Reply #4 on: February 25, 2004, 12:44:33 PM »

Mine looks like Tom's description.  I use it at Field Day.  I put the center up at about 50 feet, not quite a flat-top.  Kicks butt, S&P QRP, Elecraft K2.  I hear everything, and I can work 'em, too.
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KG4IGC
Member

Posts: 2




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« Reply #5 on: September 21, 2008, 12:19:05 PM »

I am using the formula that I found in the ARRL publication of Wire antenna classics written by Bob, N1EDM . W(ft)=984/f(14.200) to determine the electrical length of the wire in feet. The overall length of each leg will be calculated by L=W*0.64. I have had great results with EDZ's in the past and absolutely love them. I just recently had to take mine down along with all my other wires due to some roofing work and the fact that I had to have two dead trees removed. I am now in the process of building three new ones designed for 14.200. I will be using #14 wire for each Zepp, each antenna and feedline will be exactly the same so that I will only have to tune the antennas one time. The three EDZ's will be in the shape of a triangle when put up on my supports and hooked up to a switchbox mounted outside,controled by a remote switch here in the shack. I will be feeding them with 450 ohm window line run to my MFJ-969 tuner. Due to the success that I have hade with EDZ's in the past, I think that this will be a great setup for contesting and also DXing.

Cheers and 73,
Frank KG4IGC
Freewebs.com/kg4igc
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