[Elecraft] K3 5 pole vs 8 pole filters - attenuation in the passband

[Jim Brown]

On Fri,2/26/2016 8:50 AM, lstavenhagen wrote:
> Quick question - do the 8 pole roofing filters have more attenuation, as a
> general rule, in their passbands than the 5 pole?

Yes, but the difference doesn't matter -- it's in the IF, not the front 
end. Further, there is an menu adjustment for each filter to equalize 
the IF gain when switching between filters.

The advantage of 8-pole filters is smoother response in the passband of 
wider filters, and steeper skirts. In general, roofing filters are only 
needed for high QRM conditions like contesting. Their function is to 
protect the DSP from overload by strong signals outside the desired 
passband.  When the DSP IF is set to a bandwidth close to that of the 
roofing filter, the two filters cascade to provide even steeper skirts. 
Again, needed only under contest conditions.

It's amazing the things one can learn by reading the manual. :)

73, Jim K9YC