[Elecraft] Re: roofing filter loss and method of compensation

[wayne burdick]

On Apr 29, 2007, at 11:50 AM, Toby Deinhardt wrote:

> The big questions are:
>
> 1) Why would I want a 8 pole file and not a 5 pole with almost the 
> same bandwidth? Rejection, ringing, etc. etc.?

The 8-pole filters will have somewhat sharper skirts. This could be 
useful in certain QRM situations. Of course the DSP will provide 
incredible ultimate attenuation -- the opposite sideband simply won't 
exist, at any signal level.


>
> 2) What is the difference between the 2.7kHz and 2.8kHz - 
> advantage/disadvantage?

We wanted our 5-pole filter to be slightly narrower. As I mentioned 
above, the 8-pole filter will have steeper skirts, at a higher price.

You can install additional filters at any time, by the way. We hope to 
have variable-passband CW and SSB crystal roofing filters within a few 
months, so you could save a slot or two.


>
> 3) How do the fixed bandwidth filters compare with the variable 
> bandwidth roofing filters?

We haven't nailed down the variable bandwidth selections, but chances 
are we'll have a CW-range variable filter (maybe 300-800 Hz) and an 
SSB-range variable filter (say, 1.8 to 2.5 kHz).

73,
Wayne
N6KR


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