[Elecraft] K3 filters

[Darwin, Keith]

Yes, that is what the theory says, but I think there is variation in
filter implementations such that some 8 pole filters ring worse than
others.

With the DSP, one approach is to use a 5 pole filter to get a less ringy
first filter followed by the DSP which adds the extra selectivity to
achieve the ultimate rejection and elimination of signals outside the
roofing filter.  This might give great selectivity with less ringing
than trying to put all that selectivity in the crystal filter.

- Keith N1AS -
- K2 5411.ssb.100 -
- K3 Wave 3 -

-----Original Message-----
From: Alan Bloom [mailto:n1al at cds1.net] 

An 8-pole filter should have more ringing than a 5-pole filter of the
same bandwidth and ripple.  That's because the loaded Q of each pole
(crystal) is higher (bandwidth of each pole is narrower).  You can think
of it as each crystal covering 1/8 of the bandwidth rather than 1/5,
although that's an oversimplification.