Martin, There are 2 parameters to consider when making the filter settings - 1) the width of the filter, and 2) the BFO setting. It is the BFO setting that will change the position of the passband. You apparently have the BFO setting incorrect.
Use a noise source rather than a signal when observing the position of the passband with Spectrogram and set the BFO so that the passband is properly positioned. See my website www.w3fpr.qrpradio.com article dealing with K2 Dial Calibration for detailed information for setting the reference oxcillator and the filter/BFOs. 73, Don W3FPR > -----Original Message----- > I ran through the K2 filter aligment considering all your tipps and > tricks. I also adjuest the reference oscillator > on the control board again. My filter bandwidths are 1.5 kHz, 700 Hz, > 500 Hz and 200 Hz (Filter FL1 to FL4). > > I have used Spectrogram to align the filters. The settings are matching > with zero beat tests on a carrier. > > Now Fliter FL1 to FL3 are working perfectly. I can switch through the > filters and the tuned signal stays with > maximum amplitude in the filter with minimum frequency change. > > The strange thing: Filter FL4 was not working. So I have set it's > bandwidth to 2 kHz and analysed the passband > By tuning over a carrier observing the peak in spectogram. I have seen, > that the center frequency of FL4 > is different from FL1 to FL3! > > How can that be, because the Filter settings FL1 to FL4 are controlling > the same electrical filter?!? > > -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.323 / Virus Database: 267.7.7/20 - Release Date: 6/16/2005 _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
