[Elecraft] Filters

[Darwin, Keith]

Multiple peaks?  At what bandwidths?

My K2 give nice flat filter shapes at bandwidths 1000 Hz and narrower.
At SSB bandwidths, the filter passband has several or more very large
peaks and has a gentle roll off in either lows (USB) or highs (LSB).
Even at widths of 1.6 KHz the passband shows a couple of big peaks.

In contrast my IC-735 shows a nice flat passband with no slope to it
(thus proving the issue is not my PC sound card or the way I ran
spectrogram).

I did some screen shots and sent them to Elecraft support to see if it
was a problem.  No it's not.  The Xtal filter was optimized for variable
bandwidth over CW bandwidths and doesn't work as well at SSB widths.

Apparently the fixed-width filter in the SSB adapter does not have this
issue.

Your post sounds like your rig is not "right".  My rig has the new
generation matched Xtal filters and I put in the 2nd set of grounding
straps (per the instructions in the KSB2 documentation IIRC).

Oh, and with spectrogram, I got much better results if I let it filter /
average over 3 seconds or so.  That really suppressed the noise and
showed the filter shape more accurately.

- Keith KD1E -
- K2 5411 -

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of james1787 at aol.com
Sent: Tuesday, May 23, 2006 9:38 AM
To: elecraft at mailman.qth.net
Subject: [Elecraft] Filters

The filters in my K2 have always been a little weird. Tuning around, the
signal would always peak at the wrong point and then drop when it's at
the correct sidetone frequency. I lived with it for a while. I finally
took some initiative and tried it out with spectrogram and using the
Elecraft noise generator. My findings were a bit suprising. 
The filter shape has multiple peaks and is not uniform at all.. 
compared to a few others I have seen. I compared it to another friends
K2 and it was confirmed - my filter shape is funky.

What should I do? Do I need to buy new crystals? Is something out of
whack?

Thanks,

James Kern KB2FCV
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