[1000mp] cw fiters

[Jim Smith]

You're getting more than steeper skirts.  Most filters don't have skirts 
that go on forever.  They usually have a stopband spec which says 
something like "the response in the stop band shall be at least 80 dB 
below that of the passband".  So, skirt selectivity notwithstanding, 
with one 250 Hz filter in the 8 meg IF you will hear blow-by (as I do) 
from very strong signals adjacent to the passband.  Add a 2nd filter and 
now the stopband is at -160 dB (assuming perfect shielding of everything 
including a shield between the input and output terminals of the 
filters).  I don't find this blow-by that objectionable.  However, my 
next filter purchase is going to be the 250 Hz 455 Inrad.

73 de Jim Smith    VE7FO

Tom Rohlfing wrote:

>
>
>If you don't use WIDTH, it isn't quite so important.  All you are doing is
>getting steeper skirts with a pair of filters.  But the WIDTH is a pretty
>effective tool, so for me it's worth it to have a matched pair.
>
>
>73,
>Tom / W7GT
>