This topic has been pretty thoroughly discussed, so excuse my additional comments. In summary, I think the majority feel either the 2.7 or 2.8 KHz filter adequate for "general use", since one has the ability to narrow bw using DSP.
I have only the 2.8 (in both Rx) and 400-Hz filter (in the main Rx). I do mainly weak-signal work where narrow bw is important to reduce "white noise". On CW-eme it is common to run at 100Hz for this purpose as it increases SNR. The DSP filter handles that really well since the objective is to eliminate noise at the detector (which the DSP filter does). A narrow roofing filter has significant use keeping strong off-freq RF from causing IMD, or affecting the RF gain stages. This is typically found in high-density HF contests (which I do not participate in). I chose the 8-pole filters thinking the steeper skirts might offer a slight advantage in crowded band conditions. For HF CW the 400-Hz filter makes copy really "arm-chair nice" as it "almost" results in hearing only the one intended station in the passband. On CW-eme I haven't decided if 400-Hz roofing filter offers any advantage over the DSP filter. I suspect not. That all being said, I did order the roofing filter for my new KX3. Why? Because I expect to travel with it to areas where that will be more important. Hill-toping with it portable can expose one to nearby strong signals (even IF feed-thru when running with VHF-mw transverters). Being a direct-conversion SDR, RF filtering is more important to keep out unwanted RF energy. So roofing filters generally will not hurt performance if used and may help in some situations. 73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-? DUBUS Magazine USA Rep dubus...@gmail.com Coming Soon - "Kits made by KL7UW" ====================================== ______________________________________________________________ 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
