Group,
At the risk of starting up another somewhat off topic discussion,
I have a question for this elite group which hopefully has a
simple answer.
In the February 2001 issue of QST (p42) is an article entitled
"How to Maximize Your Receiver's Effective Selectivity". He uses
Kenwood rigs in his discussions but filter selectivity applies to
any rig including Ten-Tec's. In discussing the theory of his
conclusions, the author (w4QEJ) shows several figures where he
chooses to invert the typical selectivity curves showing maximum
attenuation at the top of the curve instead of the bottom. That's
OK, you can to that. However, when he plots the amplitude of
signals and noise on this upside down curve he shows the
increasing amplitude of the signals in the direction of increasing
attenuation. While his conclusion is correct, that is, you can
sometimes improve the intelligibility of a signal in the presence
of noise and interference by inserting attenuation in the receiver
front end and/or reducing RF gain, it seems to me that his
reasoning is completely wrong and every one of the curves he shows
from Figure 5 on is wrong.
Please tell me that I'm confused and QST didn't really print an
almost totally incorrect article (only Part I of II) and it's not
even April.
----
73, Rich - W3ZJ
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