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[Towertalk] Common-Mode choke at 430 MHz.

To: <towertalk@contesting.com>
Subject: [Towertalk] Common-Mode choke at 430 MHz.
From: Larry Bush" <w5ncd@bigfoot.com (Larry Bush)
Date: Wed, 17 Jul 2002 12:30:25 -0500
Am building a couple of 8 element 430 MHz Yagi on 1 inch PVC boom.

The driven element is a dipole with direct feed RG-58A. I thought a
common-mode balun wound with the RG-58 around the 1 inch OD PVC boom would
be neat so I computed the reactance needed was .4 micro-Henry, which is five
turns on the boom. During my research I was could not find the use of
common-mode baluns on frequencies higher than 6 meters. I have three
questions:



1                     Will a common-mode choke work on 430 MHz?

2                   Will the capacity coupling between turns of the balun at
430 MHz make the choke ineffective and if so would winding the balun by
spacing the turns the diameter of the RG-58 help?

3                   How would one check the common-mode currents on the yagi
models?





Larry Bush, W5NCD



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