From Bill Tippett <[EMAIL PROTECTED]>
From the
FAQ of Inrad's paper on roofing filters by W2VJN:
"5. If 6 poles work so well, why not 8 poles?
Eight poles would provide much better
stop-band isolation, but it's not required in a roofing filter and would
make no
noticeable improvement in IMD performance."
---------------------------------------------------------------------------
A moot point I would suggest Bill when the symmetry (or lack of) a Ladder
filter's response is also considered. The more poles the better in a Ladder
roofing filter to improve symmetry provided that the IMD generated within
the filter does not become a limiting factor, a point that Jack K8ZOA has
noted. To preach to the choir, filter IMD performance is usually measured
early on in a receiver's design exercise prior to fixing the Gain
Distribution.
73,
Geoff
GM4ESD
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