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Author Topic: 70 cm cross-yagi  (Read 1969 times)
KC9ERZ
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Posts: 17




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« on: August 01, 2009, 07:07:23 PM »

I just purchased a Yaesu G5500 Az/El rotator and want to make a couple circular polarized Az/Ez Yagis for 2 meter and 70cm.  I have attempted to make a cross yagi for 70 cm using the "cheap yagi" design.  I've also tried mounting them 90deg out of face on the same boom.  I then tried creating the power-divider harness.  I can never seem to get a low SWR.  It seems that every 1/16 inch or so you are off really is compounded when you put everything together.  

Anyway have an easily reproduced 70 cm antenna that is good for working the LEOs?  I'd prefer something directional, since I have the Az/El rotator.

Thanks for your help!
Greg
KC9ERZ
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KC9ERZ
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Posts: 17




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« Reply #1 on: August 02, 2009, 05:15:56 AM »

Sorry for all the "typos" in the first post.  The following is an amended version.

I just purchased a Yaesu G5500 Az/El rotor and want to make a couple circular polarized Yagis for 2 meter and 70cm. I have attempted to make a cross yagi for 70 cm using the "cheap yagi" design. I've also tried mounting them 90deg out of phase on the same boom. I then tried creating the power-divider harness. I can never seem to get a low SWR. It seems that every 1/16 inch or so you are off really increases the SWR.

Anyone have an easily reproduced 70 cm antenna that is good for working the LEOs? I'd prefer something directional, since I have the Az/El rotator.

Thanks for your help!
Greg
KC9ERZ
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N3OX
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Posts: 8852


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« Reply #2 on: August 03, 2009, 08:33:09 PM »

"I then tried creating the power-divider harness. I can never seem to get a low SWR"

Have you tried to get a low SWR on each yagi individually?

And when you make the phasing harness, have you *measured* the velocity factor of the coax?  It can vary, and if you don't have the right electrical length that could make it impossible to get a good SWR and correct pattern even if each antenna is working great.


73
Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
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