John, Given that information, I conclude that you have an unusual situation with your KSB2 filter. The easy way to attempt a fix is to replace both the crystals and the capacitors (SSBCAPKT). Total cost is only $30 plus shipping, and your aggravation is likely more costly than that amount.
The design works and produced the proper results - if the components are the correct values. 73, Don W3FPR On 4/25/2011 7:35 PM, John Magliacane wrote: > Hi Don. > > Thanks for the reply. > >> John, >> >> I cannot answer your exact question (the impedance ratios), but I need to >> ask a >> question about your "narrower than expected" filter response. > I plotted a sweep of my TX chain a number of years ago, the results of which > can be seen here: > > http://www.qsl.net/kd2bd/sweep2.png > > It's a linear plot, so the ripple and other imperfections really stand out. > It was taken by sweeping audio through the KSB2 well below the level of ALC > action while measuring the corresponding audio level picked up by a nearby > crystal controlled, direct conversion receiver having no filtering or AGC. > > Looking at the red LSB curve, if we estimate the center of the passband to > average around "70" in amplitude, -3dB would be around "50", and -6dB would > be around "35". > > > From this, I estimate the -6 dB bandwidth to be around a 2.2 kHz. And this > > is with the 2.5 kHz -3dB bandwidth (2.6 kHz -6 dB bandwidth) coupling > > capacitors in the ladder. > > And, lastly (although less scientific), if I optimize my CAL FIL settings so > that my transmitted audio has the identical quality on LSB that it has on USB > (as observed on a wideband receiver), my BFO settings are only 2.3 kHz apart. > This is 400 Hz less than the spacing suggested in the KSB2 instruction > manual for a 2.2 kHz (-6 dB) bandwidth. > > > 73, de John, KD2BD > K2/100 #3563 > > ______________________________________________________________ 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
