If I wanted to check for filter offsets in the 8 pole filters, I think I would put them into the main RX and run response curves (using the K3 Filter Utility package) in both USB and LSB (or AFSK A NOR and REV). Set the DSP bandwidth to 4.00 and the center frequency to 1.50 (SSB) or 2.20 (AFSK A) to minimize the DSP contribution to the response.
One set of data would need to be inverted and offset to compare the two responses but one could overlay the two curves and look for any asymmetry ... I would check specifically to see if the -3 dB points were spaced equally above/below the center frequency. The skirts will not be symmetric in LSB/USB due to the sharp cutoff near the carrier in USB/LSB (1500 - 1400 = 100 Hz). Any offset may be more apparent using the AFSK A settings. 73, ... Joe, W4TV > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Windy Dankoff > Sent: Sunday, April 12, 2009 10:28 PM > To: [email protected] > Subject: Re: [Elecraft] K3: Optimizing filter offsets for SSB > TX and RX > > > YOU ARE RIGHT, Joe !! I did my trials on USB. On LSB, I can tell by > listening and re-adjusting that you are quite correct. It's back to > zero for me. > > :-| > > I await further comments. > Windy > > > On Apr 12, 2009, at 5:10 PM, Joe Subich, W4TV wrote: > > > > > If you crank in an offset with the 8 pole filters be sure you test > > it with BOTH USB and LSB. An offset that enhances low frequency > > response in USB will reduce the LF response in > LSB (enhance > > high frequency response) and vice versa. > > > > 73, > > > > ... Joe, W4TV > > > >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
