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

[wayne burdick]

Wow, Toby, that *is* a complicated question, partly because we haven't 
nailed down the specs for our variable-passband roofing filters yet. 
I'd leave room for at least one of those (CW or SSB bandwidths).

Here's a set that covers all modes including AM and FM:

   FL1 = FM bandwidth (something like 13 kHz)
   FL2 = 6 kHz (AM; wide SSB)
   FL3 = 2.8 kHz (workhorse SSB filter)
   FL4 = 500 Hz (nominal CW)
   FL5 = 200 Hz (narrow CW)

If you were doing primarily SSB, you might want to go with 1.8 or 2.1 
kHz at FL4. At present these filters are only offered by INRAD. We plan 
to offer a variable-passband 5-pole filter that covers something like 
1.8 to 2.5 kHz that would fill this bill in the future.

Having used something different at FL4, you'd then need to reevaluate 
FL5. It could be 400 Hz (INRAD fixed), 500 Hz (Elecraft fixed), or even 
an Elecraft variable CW/DATA bandwidth filter -- TBD, but probably 
something like 300-600 or 300-800 Hz.

Of course this assumes that you want AM and FM-bandwidth filters. If 
you don't operate in these modes, you'll have more SSB/CW/DATA filter 
flexibility. You could also put narrower filters on the sub-receiver.

73,
Wayne
N6KR

On Apr 29, 2007, at 1:13 PM, Toby Deinhardt wrote:

> Hi Wayne,
>
> I know that this is a really loaded question, and I am sure that if
> you put three hams in a room you would get 7 opinions...
>
> What combination of filters (fixed and/or variable) would you feel are
> appropriate for...



> ---

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