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Old August 13th 03, 05:30 PM
W5DXP
 
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Dr. Slick wrote:

Roy Lewallen wrote:
Sure, you can normalize a Smith chart to anything you'd like. That
doesn't make the SWR change with source impedance.

I disagree on this point. You are caught up in the 50 Ohm world,
which i admit is easy to do. The SWR is based on the ratio of the
forward to the reflected power. If you had an analyzer that was
calibrated to 20 Ohms (the same as normalizing the Smith for 20 Ohms
in the center) you would certainly have reflected power and high SWR
going into a 50 Ohm load.


Not if the feedline has a Z0 of 50 ohms. The problem would be in believing
what you believe about what the 20 ohm SWR meter is trying to tell you.

It is trying to tell you that it is being misused but you are inferring
that it is trying to tell you the actual SWR. It is not.

And a 20 Ohm load would have a 1:1 SWR.


Not if the feedline has a Z0 of 50 ohms. If a DC voltmeter gives an
erroneous reading for RF voltage, do you blame the voltmeter or the
user of the voltmeter?
--
73, Cecil http://www.qsl.net/w5dxp



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