[Elecraft] K2 Filter settings

[Jeff Kinzli N6GQ]

I'll be the third to chime in on how useful the spectrogram method of
aligning filters is. The first time around (without spectogram) I
noticed similar results as you did, then I did the spectrogram
alignment and it got *much* better, but it still wasn't right. Third
time, it got even better. I'll be doing it again this weekend I think,
it's somewhat of an art but it's also gratifying to see how much of a
change it really can make.

As Don said, you can do this anytime, no cause for concern at this point.

73,

Jeff N6GQ

On 3/16/07, craig_young at att.net <craig_young at att.net> wrote:
> Nick,
>
> I wholeheartedly second this.  I followed the manual and noticed the same thing you did.  When I hooked up Spectrogram I could clearly see that the narrower filters were off center.  I adjusted while watching the Spectrogram screen and things sound *much* better.
>
> Craig AC6NN
>
>
> -------------- Original message ----------------------
> From: "Don Wilhelm" <w3fpr at earthlink.net>
> >
> > Nick,
> >
> > Sometimes the filters (particularly the narrower ones) do not respond well
> > to the initial numbers in the manual because the filter center may be
> > shifted a bit due to the particular set of matched crystals supplied.  I
> > don't think you have a problem.
> >
> > There is a solution, and that is called 'Spectrogram', which will provide a
> > visual display of the filter shape and positioning on a computer screen.
> > Download the last freeware version (5.17) of Spectrogram from www.n0ss.net
> > and look at the instructions for using it on Tom's website or the Builder's
> > Resource page of the Elecraft website.
> >
> > You could let the filter alignemnt wait until you have the rest of the K2
> > built and the KSB2 (if you added that) installed and then you can do a
> > complete dial calibration and filter alignment.  Instructions for doing that
> > are on my website http://w3fpr.qrpradio.com
> >
> > 73,
> > Don W3FPR
> >
> > > -----Original Message-----
> >
> > >
> > > Thrilled to get my K2 working on 7 MHz receive but I seem to have
> > > a problem with filter settings.
> > > Everything has checked out according to the book - no problems at
> > > all (even my home-wound coils seem to work!!)
> > > I have set up the filters exactly according to pages 88 and 89.
> > > On Filter 1 the rx sounds great - plenty of gain, clean signals.
> > > On the other 3 filters it sounds like I am listening through a
> > > dense fog - I can tell the bandwidth is far narrower than F1 but
> > > signals are weak and it sounds as if the filters are overlapping
> > > each other (if you know what I mean). I have checked settings
> > > again and all look OK. Does anyone recognise this problem please?
> > > I am reluctant to proceed until I have sorted it out.
> > > 73 Nick G3RWF
> > >
> > --
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