[Elecraft] K3 roofing filter group delay

[Don Wilhelm]

Brian and all,

The number of poles is not the primary deciding factor.  It is the type 
of filter (Cohn, Chebychev, Butterworth, Gaussian to 6 dB, Gaussian to 
12 dB, etc.) that will influence the group delay.  See the discussion on 
filters in Experimental Methods for RF Design for further information.

In general, those filters with a 'rounded nose' will have the best group 
delay characteristics - but that is only a generalization, the details 
will tell "the rest of the story".

73,
Don W3FPR

Brian Lloyd wrote:
> A number of messages have gone back and forth here about roofing 
> filters. We did mention group delay but I wonder if Elecraft can provide 
> group delay characteristics for the various filters offered for the K3.
> 
> Seems to me that, in general, fewer poles tend to provide better group 
> delay in a filter at the expense of the skirts. OTOH, if the skirts in 
> the roofing filter are sufficient to attenuate a strong, undesired 
> signal so that it cannot cause desense, then it strikes me that the 
> 5-pole filters might actually provide superior performance for digital 
> communications.
> 
> 73 de Brian, WB6RQN
> Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT com
> 
> 
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