Thanks to Don and Robert for the quick and thorough responses about setting up the DSP filters. I will experiment with the settings now that I understand a little bit better.
On Jan 30, 2013, at 8:57 PM, Don Wilhelm wrote: > Kevin, > > Usually the KDSP default filter widths work fine, I would suggest that you > leave CW AFIL1 set for LoPass and normally use the IF filters for general > use. When you encounter QRM, then first narrow the IF filter, and then if > still needed, start down the AFIL steps to resolve the signal. > In other words, there is only marginal benefit in using a 150 Hz KDSP2 > bandwidth if your IF filter is set to 1.5 or 0.7 kHz. The offending strong > signal will still take over the K2 AGC and you will hear 'pumping' because > the strong offending signal is controlling the AGC. > > The KDSP2 filter skirts are steeper than the IF crystal filter skirts, and > that is the main advantage. > Narrower bandwidth is not always the best cure, but the choices are entirely > yours to make. Experiment a bit while listening to DX Pileups or during a > "hot and heavy" contest where the bands are crowded, and that experience will > give you the information you need to set the KDSP filters the way they will > be of the most advantage to you. Your current setting may be quite adequate. > Your goal should be twofold - first is to reduce QRM from adjacent signals, > and the second is to be able to pull weak signals out of a crowded band. > More narrow filter widths are not always the way to make that happen, but > escaping from QRM with steeper filter skirts may work better. A lot depends > on your tuning skill as well as selection of the proper filters and the best > way to develop that skill is to try it out on crowded band conditions. > > It may be that you simply want to set the KDSP bandwidth to the same widths > as the IF filters to take advantage of the steeper skirts. In other words, > use AFIL2 in conjunction with IF FL2, AFIL3 in conjunction with IF FL3, etc. > It is rare that you will need less than 200 Hz of filter width, but YMMV. > > 73, > Don W3FPR > > ______________________________________________________________ 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
