Don your are the man Once again you have helped a Elecraft product on it´s way
15pF across pin 3 and 6 of U11 pulling the crystals did make the difference. Now the BFO range are within the window given in the manual. Also the reports on my LSB modulation are way better. Not in the prefect level, but way better then it was... I would say with some more filter tuning on the FL1 for TX and the Smaller bandwidth filters for SSB. #5111 are fit for fight for more qso. Looking back in the manual at my own notes it is now clear, that I ignored the warning signs when the limits of the BFO was tested. One end are indeed not within the window. Properly intoxicated from the solder fumes and the eagerness to build you get from a K2 made me never to readdressed that fact. Thanks Don I owe you a beer.. Maybe in Dayton 73 de OZ1BZJ Michael -----Oprindelig meddelelse----- Fra: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] På vegne af Don Wilhelm Sendt: 12. oktober 2010 01:22 Til: Michael Jensen Cc: 'Elecraft' Emne: Re: [Elecraft] K2 LSB Modulation issue Michael, First a comment - why use SSB FL4 set to 700 Hz width for PSK and have to remember to turn the compression off when using digital modes? It is much easier (IMHO) to go to the secondary menu and turn the RTTY filter set on. That gives you a compression setting independent of that used for SSB - just set it to 1:1 for the RTTY filters and be done with it. I usually set RTTY FL1 the same as SSB FL1 OP1 filter and the BFOs the same. That gives you a full width passband for normal point and click in the waterfall. Then I set FL2 to 1.00, FL3 to 0.70 and FL4 to 0.40 to give narrow RTTY filters when QRM shows up - yes you have to tune to the filter center with the VFO, but at least you can continue operating. Center the narrow RTTY filters at 1000 Hz, and easy number to remember and it works well with MMTTY when the mark frequency is set to 915 Hz. Now on to your question - yes, that is a problem - the low end of your BFO range is too high. You can increase both C173 and 174 keeping the ratio close to 3:1, or you can try an easier fix first, solder a small value capacitor from the juction of the crystals to ground (U11 pins 6 and 3 maje nice anchor points). I would not exceed 27 pF with this added capacitor because it can decrease the BFO RF voltage level. Check both the high and low end of the BFO range after making this change (see manual page 62). The high must be greater than 4916.3 and the low less than 4912.7. If you cannot achieve the correct range with this single capacitor addition, you will have to change both C173 and C174. I would try 100 pF and 330 pF to see if that brings it into range. You may want to write down the frequencies (not the DAC values) of the BFOs that you already have set because all the BFO settings will be shifted and you will have to do the filters over again. 73, Don W3FPR ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
