What is the two tone dynamic range of the K3 when both signals are inside the roofing filter bandwidth?
Close-in IMD measurements are virtually always done using a CW bandwidth filter. None of the published data (ARRL, Sherwood Engineering) tests IMD inside the DSP process without xtal filter selectivity. My experience with a homebrew K3-like topology, except a strong diode second mixer (instead of NE602-type mixer), is the limiting factor INSIDE THE ROOFING FILTER bandwidth can be the DSP performance. If you put a FLEX DSP processor behind a K3 2.8 KHz SSB filter you would have FLEX numbers close in, K3 numbers outside the roofing filter. The advantages of both. So rather than bandaid by buying more filters, or push for a variable filter, if the dynamic range inside the filter is not good enough one should concentrate on (1) strengthening the post-xtal-filter intercept of the receiver circuits and (2) reducing the close-in phase noise of the LO. Bill - W7AAZ ______________________________________________________________ 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
