[Elecraft] Let's Try This Again -- was "[K3] ... A 750 Hz, 8-Pole ... Filter?"

[ussv dharma]

Lets really mess with contesters minds....give them a report of "20db over S2."

grandmaw Susan


If you don't change direction you WILL arrive exactly where you're headed!! Susan Meckley, Skipper W7KFI-mm  AFA9SM                         USSV DHARMA 


--- On Thu, 7/15/10, Wayne Burdick <n6kr at elecraft.com> wrote:

> From: Wayne Burdick <n6kr at elecraft.com>
> Subject: Re: [Elecraft] Let's Try This Again -- was "[K3] ... A 750 Hz, 8-Pole ... Filter?"
> To: "Jim Brown" <jim at audiosystemsgroup.com>
> Cc: "elecraft at mailman.qth.net" <elecraft at mailman.qth.net>
> Date: Thursday, July 15, 2010, 8:01 AM
> It *is* difficult to build very
> narrow 8-pole filters with low loss.  
> That's one reason Elecraft offers a 5-pole, 200-Hz unit.
> 
> 5 poles is entirely adequate at these narrow widths. Our
> 2-kHz IMD  
> dynamic range using the 200-Hz filter is outstanding.
> 
> We've had some requests to offer a 270 or 300-Hz 5-pole
> filter, which  
> would be better optimized for narrow-shift RTTY than the
> 200-Hz  
> filter. We're also considering a dual-passband filter
> (500/270 or  
> 500/300) that would fit in one slot.
> 
> 73,
> Wayne
> N6KR
> 
> 
> On Jul 15, 2010, at 10:18 AM, Jim Brown wrote:
> 
> > On Thu, 15 Jul 2010 14:53:10 +0100, Ian White GM3SEK
> wrote:
> >
> >> Agreed. 250-270Hz would be the "sweet spot" for an
> 8-pole filter, to
> >> guarantee good sales for the manufacturer *and*
> good performance  
> >> for a
> >> range of users in heavy QRM.
> >
> >> Now let's see if Inrad or Elecraft take the bait
> :-)
> >
> > Hang on a minute, guys. Inrad builds a nominal 250 Hz
> filter, Elecraft
> > tests and re-sells it, and we buy it, because we've
> agreed that it's a
> > sweet spot operationally.
> >
> > The issue is that it's wider than than at the -3dB
> points. So the
> > problem appears to be that it's pretty difficult to
> build an 8-pole  
> > 250
> > Hz filter at 8.8 MHz, and that Inrad has given up on
> doing better.
> >
> > 73, Jim K9YC
> >
> >
> >
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