[Elecraft] 2.7 vs 2.8

[Tom W8JI]

<<Why?  If there's a single offending station, using the 
shift control with a
2.8Khz-8pole filter will be just as effective as with a 
1.8Khz-8pole filter
in minimizing the interference since the slopes are 
similarly steep.>>

I'm not a big fan of excessive shifting of passbands to 
clean up QRM. The problem is the change in passband would 
add other problems like noise that is lower pitched or, 
depending on the IF and selectivy system, even a little 
opposite sideband response. A narrower filter is always the 
better option performance-wise.

The only debate is in cost vs. benefit. With passband tuning 
(IF shift) and narrow and wider filters, I find myself 
almost always using the narrower filter. Part of the reason 
is if the band is clear away from the offending station, it 
is easier to get everyone to turn the VFO dial. When there 
is no room to move a little, then it is very obvious there 
is QRM both above and below. For me it is a no-brainer. I 
always buy an assortment of filters for each mode that 
includes normal and "extra narrow".