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Old September 12th 06, 11:20 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Jul 2006
Posts: 296
Default 20m "ringo"


"Cecil Moore" wrote in message
...
Jimmie D wrote:
Cecil, I got the antenna up Sunday, for now the stub is straight out from
the antenna. Is it normal for the 50 ohm point to be a little hard to
find? About the best VSWR I can get now is 1.7:1 This is pretty close to
the point where my radio starts limiting power. I m thinking either the
stub or the antenna may be a little long is there an easy way to tell or
is easier just to try something and see what happens? Checking the VSWR
at differerent freqs doesnt help much. Maybe a slight indication that it
is too long.


You've discovered the problem with SWR meters. They
don't read phase. If you were using an antenna analyzer,
the solution would probably be obvious. With only an
SWR meter, your tuning algorithm either converges or
diverges but you may not know which. The easy way to
tune the antenna is to use an antenna analyzer to
determine where the impedance is purely resistive and
then adjust the stub tap point to 50 ohms. An antenna
analyzer is a good investment.
--
73, Cecil http://www.w5dxp.com


I think before I start cutting I will try adding a little series capacitance
or inductance to the antenna and see how it reacts to that. My work week
just started so it may be a week or so before I get back at it again.


 
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