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Author Topic: End Fed Zep  (Read 1723 times)
N8CHR
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Posts: 34




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« on: July 13, 2012, 06:35:48 AM »

I just purchased an MFJ End Fed Zep. " I know I could have just as well build one but have several projects going at once.
Question: What the best way to hang this for best performance? I have several tall trees over my house. Could I put one end in a tree and tie the other end off the roof?
 Any ideas, please
 Thanks Tom N8CHR
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KB3TXH
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Posts: 44




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« Reply #1 on: July 13, 2012, 07:59:21 AM »

My home brew E.F.Z. works well enough with the far end tied to a tree, and the near end, parallel feed, run up a set of surplus fiberglass poles, next to the house.

The half wave end fed I tried first (with a single feed wire into the house) gave me a lot of RFI.

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W5DXP
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« Reply #2 on: July 13, 2012, 08:08:26 AM »

Remember to keep the ladder-line about 6" away from metal and install a good 1:1 choke on the coax at the coax/ladder-line junction.
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73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
WX7G
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« Reply #3 on: July 13, 2012, 08:35:44 AM »

What ladder line to coax junction? The ladder line should be run all the way to the tuner.
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W5DXP
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« Reply #4 on: July 13, 2012, 06:04:26 PM »

What ladder line to coax junction? The ladder line should be run all the way to the tuner.

He didn't say what frequency the MFJ Zepp is for but 1/4WL of ladder-line may not be enough to reach the shack. In addition, the MFJ end-fed Zepp is like a J-Pole. The 1/4WL ladder-line is shorted at the bottom and is tapped at the 50 ohm point above the short. Coax is expected to be connected at that 50 ohm tap point and I recommend a 1:1 choke on that coax.
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73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
WX7G
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Posts: 6128




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« Reply #5 on: July 15, 2012, 09:44:17 AM »

Now I see. That is an interesting way to build a Zepp.
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W5DXP
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« Reply #6 on: July 15, 2012, 06:40:12 PM »

Now I see. That is an interesting way to build a Zepp.

It ensures that the MFJ Zepp will have a feedpoint impedance of 50 ohms, something that the traditional Zepp design cannot guarantee.
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73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
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