[Elecraft] K3 2.7 k Filter vs. 2.8 k

[Don Wilhelm]

Mike,

Not necessarily.  As long as the signals within the passband of the 
roofing filter are not strong enough to overload the DSP, that is 
sufficient.  In other words, the ultimate rejection of the roofing 
filter is not critical.  If the roofing filter is able to knock down the 
unwanted signal to a level the DSP can handle, then the DSP will not 
overload and the DSP itself will provide great ultimate rejection.  
These are roofing filters and not final filters.  If they were final 
filters, then the ultimate rejection would become important.

There is an article on roofing filters in Oct QST that may help to explain.

73,
Don W3FPR

Corboy-Poteet wrote:
> I have a question. The standard IMD test is a two tone test. In a
> contest type situation with multiple strong signals in close
> proximity, wouldn't greater ultimate rejection by the crystal roofing
> filter be a significant advantage?
>   
>