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Re: [TowerTalk] 75 ohm - v - 50 ohm coax

Subject: Re: [TowerTalk] 75 ohm - v - 50 ohm coax
From: Steve Hunt <steve@karinya.net>
Date: Tue, 19 Feb 2013 18:54:43 +0000
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
The SWR on the 75 Ohm line will be 1.5:1, but if the line is a quarter-wave or odd multiple long, the 50 Ohm load impedance is transformed to 75*1.5 or 112.5 Ohms - that's an SWR(50) of 2.25:1.

In fact any line length between 0.15 wavelength and 0.35 wavelength will transform the load impedance to produce an SWR(50) greater than 2:1.

73,
Steve G3TXQ



On 19/02/2013 14:10, Jim Thomson wrote:

If the antenna has an impedance of 50 Ohms, and the coax is close to a
quarter-wave or odd multiple long, you'll see an SWR(50) of 2.25:1 at
the shack end instead of 1:1.

73,
Steve G3TXQ

##  I thought it would be just 75/50 =  1.5:1



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