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Author Topic: Use of antenna analyser on open wire feed  (Read 295 times)
MM0RAG
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Posts: 17




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« on: August 19, 2008, 12:58:08 PM »

Hello,

I am planning to erect an 80m dipole, feed it with open wire feeder, and tune for all bands from 80-10 using a link coupled antenna tuner.
My question is: I have an MFJ antenna analyser which has only a co-ax input. I think that if I use the analyser on the input to the ATU I should be able to set up the atu for all the frequencies that I want to use and avoid any possibility of problems with transmitting into a poorly tuned system.

Is this the correct approach?

Thanks
MM0RAG
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WA3SKN
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Posts: 5436




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« Reply #1 on: August 19, 2008, 01:04:55 PM »

I take the coax off my radio and connect it to the MFJ259b, then adjust the tuner for 1:1 SWR with zero reactance.  Then re-connect to radio.  The MFJ unit uses much lower power, minimizing any possible interference when tuning up.
Works great!
73s.

-Mike.

ps: The MFJ is limited to 1000 ohms resistive and 650 ohms reactive, most antennas meet this.
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WA3SKN
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Posts: 5436




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« Reply #2 on: August 19, 2008, 01:10:06 PM »

If that is an auto-tuner there won't be enough drive.  I assumed a manual tuner!
73s.

-Mike.
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W5DXP
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Posts: 3546


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« Reply #3 on: August 19, 2008, 01:17:21 PM »

Here's a lot of information on that antenna.

http://www.w5dxp.com/notuner.htm

Use a good 1:1 choke on the antenna analyzer output and it will operate properly. The choke acts like a balun.
--
73, Cecil, w5dxp.com
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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.
W9GDH
Member

Posts: 8




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« Reply #4 on: August 19, 2008, 05:26:54 PM »

Use this web site for good info and tuning. http://www.dxengineering.com/pdf/Multi-Band%20Dipoles.pdf
hook the analyzer to the same input as radio.
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