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

[Robert Tellefsen]

Wayne
Will the variable bandwidth filters have better
ultimate rejection/less blowby than the variable
bandwidth filter in the K2?
73, Bob N6WG

----- Original Message ----- 
From: "wayne burdick" <n6kr at elecraft.com>
To: "Toby Deinhardt" <dj7mgq at muenchen-mail.de>
Cc: <elecraft at mailman.qth.net>
Sent: Sunday, April 29, 2007 4:30 PM
Subject: [Elecraft] Re: roofing filter loss and method of compensation


> 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...
> 
> 
> 
> > ---
> 
> http://www.elecraft.com
> 
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