[Elecraft] Contemplating Purchase of K3

[Jim Brown]

On Sat,3/7/2015 9:11 AM, Mike Markowski wrote:
> If you're a cw operator, I make heavy use of the 400 Hz filter.  Not 
> too narrow (usually), and not too wide. 

There's a potential misunderstanding here. The plug-in filters are 
ROOFING filters, and are there to protect the IF from overload by VERY 
strong signals. The IF bandwidth is NOT dependent on those filters. 
Rather, the IF in a K3, like the KX3, is filtered by DSP. Those filters 
DO add to the selectivity of the K3 by virtue of a process called 
"cascading," whereby they make the K3's filter skirts fall off more 
sharply when the roofing filter is the same bandwidth or narrower than 
the DSP IF.

So -- you DO probably need a CW roofing filter if you're a contester, or 
if you have a close-in neighbor who is active on the same bands when you 
are. For general operation, the IF is enough.

73, Jim K9YC