Hi Chuck,
The purpose of roofing filters in the K3 is commonly misunderstood, they're primary function is to protect the receiver from overload from an extremely strong interfering signal within the passband occupied by the signal of interest. There's an excellent paper on this topic on the Elecraft web site: http://www.elecraft.com/K3/Roofing_Filters.htm You can find the plots for many of the Elecraft filters here (caution: many of the plots use different frequency spans): http://www.elecraft.com/K3/K3_filter_plots.htm There's very little difference in the performance of the Elecraft 400 Hz filters vs. their narrower bandwidth filters. The 400 Hz filter you already have is all you will ever need in all but the most extreme (and rare) interference situations. T he 1 kHz filter is a useful addition to your receiver i f you like broader bandwidth for casual CW operation, although the 2.1 kHz filter works nearly as well if you narrow the DSP bandwidth. There's very little difference between the 2.7 kHz stock filter and the 2.8 kHz 8 pole optional filter except in the most extreme interference situations such SSB DX contests where its tighter skirts of the 2.8 kHz are sometimes be helpful but the difference is small. I prefer the 2.1 kHz filter to the 1.8 kHz filter. I have both filters in my K3 but rarely use the 1.8 kHz filter and only under the most extreme inteference situations in a SSB DX contest. 73 Frank W3LPL On Thu, Mar 8, 2018 at 11:24 AM Chuck Chandler <[email protected]> wrote: > Right now I have the stock SSB and a 400 Hz filter in both main and sub > rcvrs. I would like to add some a few at a time. My first priority is to > add a couple to the main receiver, since it is the biggest chore to get > to. > > I plan on a 250 Hz CW filter, but am going back and forth between the 2.1 > and 1.8 kHz filters. I know that narrowing the DSP to 1.8 gives a really > difficult to understand voice signal, while the 2.1 allows in more adjacent > signals. However, the roofing filters may not behave in the same manner. > For example, the 1.8 could be set to turn on at 2.1 to take advantage of > skirt shape. > > I primarily DX, and operate in some contests as well. I know SSB contests > really need a narrow SSB filter. > > Any suggestions on the matter from those who have gone this route before? > > 73 de Chuck, WS1L > > -- > > > =================== > Chuck Chandler > [email protected] > =================== > ______________________________________________________________ > 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 > Message delivered to [email protected] > ______________________________________________________________ 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 Message delivered to [email protected] ______________________________________________________________ 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 Message delivered to [email protected]
