[Elecraft] 8-pole vs. 5-pole roofing filters?

[Vic K2VCO]

Darwin, Keith wrote:

> Now, the question is whether or not the 5 vs 8 pole filters for the K3
> have different levels of ultimate rejection.  If they do, then the
> choice has become tougher.

My guess is that the better ultimate rejection that you experienced when 
you compared Tentec and INRAD filters had more to do with the details of 
the installation of the filters rather than the quality of the filters 
themselves. The "blow-by" you experienced with the INRAD filter was 
probably taking place AROUND the filter as a result of stray 
capacitance, shielding, and grounding issues.

These factors will probably be more or less the same with different 
Elecraft filters. Probably the ultimate rejection of all of the filters 
will be limited by the outside factors -- the filters will be 'better' 
than the wiring.  And in the K3 the DSP will improve the ultimate 
rejection of any filter, since we assume that residual signals will be 
too small to actuate the AGC or cause IM products.

So I do not think that ultimate rejection will be a consideration for 
choosing the K3 filters.

Having said this, I'm still debating whether I should get the 5 or 8 
pole CW filters!

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco