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Re: [TowerTalk] PL-259's

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Subject: Re: [TowerTalk] PL-259's
From: Pat Barthelow <>
Date: Wed, 10 Oct 2007 18:56:59 -0700
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Carl Said:
Several published tests show a good PL-259 coming to almost a perfect 50
Ohms at 222 MHz but exhibiting a bit under 2:1 at 432. While that VSWR wont  
bother a FM wanker or scanner its not good at QRO or for that weak signal 
receiver noise figure.
I want to learn more about transmission line impedance bumps.  What effect on 
over all system SWR or loss, does the LENGTH of the geometric mismatch have?
That is,  if the inside/outside conductor diameter ratios, say inside a 
connector create, say a 2:1 SWR bump,  but are only, say 2" or say, 1/20 
wavelength long,   what overall deleterious effect do they have, as compared to 
a geometric impedance bump that is say, 5 ft, or multiple wavelengths long?  
Significant fracthional wavelegths of mismatched cables of course become 
impedance transformers..

All the Best, 73,
Pat Barthelow
Jamesburg Earth Station Moon Bounce Team

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