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Dipoles and the rig's RF ground...

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January 11th 06, 09:37 PM posted to rec.radio.amateur.antenna

Owen Duffy

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Dipoles and the rig's RF ground...

On 11 Jan 2006 01:09:41 -0800, wrote:

Where are the losses in a Ladder-
Line fed system? ....

The tuner that is usually used offsets the advantage
of the line itself. Sure, on paper you shouldn't really
be able to notice it. But I do when I test it. It's actually
measureable on an S meter when doing A/B comparisons.
Or at least it was for me when using a 989c tuner
and minimum inductance vs coax fed.

You are telling us that you have evaluated the loss of a MFJ-989C
antenna tuner + open wire line vs coax by on air A/B tests using the
S-meter as your indicator.

Presumably you used exactly the same antenna, how are you sure that
the feedline wasn't an active part of the antenna, was the measurement
made over an ionospheric path, was the A/B comparison made at
different times when other things may have changed?

What would be your confidence limits on such a experiment?

If you recorded your results, the variance would be revealing.

I suggest that the noise in your experiment would probably swamp the
true difference between your A and B configuration, and therefore your
conclusion might not be sound.

Your observation is (as you note) different to "on paper"
expectations, that might be reason to re examine the experimental
setup in search of an explanation.

Owen
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