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Re: [TowerTalk] PL259 Insertion Loss?

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Subject: Re: [TowerTalk] PL259 Insertion Loss?
From: "Paul Christensen" <>
Date: Tue, 17 Jan 2012 06:40:12 -0500
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> Somebody had to be first, and Mr E Clark Quackenbush [1] did a fine
> job... for its time, which was in the 1930s. But it's important to
> remember how long ago that was.

That ties in with why we have a 50-ohm coaxial line standard for most 2-way 
communications purposes and it probably dates back to the Quackenbush era. 
50-ohms represents the mean value between 30-ohms for best peak power 
handling and 77-ohms for lowest loss.  The arithmetic mean is 53.5, and the 
geometric mean is 48 ohms.  Roughly split the difference and round to the 
nearest whole number and we get 50-ohms.

When the application is Rx only, all else being equal, 75-ohm lines offer 
the lowest loss for a coaxial cable and the reason we see this Zo for CATV, 
Satellite TV, over-the-air VHF/UHF reception, etc.

Paul, W9AC 


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