HI all, I've previously written to Mike directly, but I now see so many comments here that seem "wrong" or potentially misleading to me (but not all), that I am compelled to comment to the reflector.
Mike said, "I just dont want to hear a 59+10 signal that is 3 kc..from the frequency I am listening on" This type of SSB interference is better controlled by the DSP final bandwidth than by the selection of a narrower roofing filter. What readers should keep in mind is that the roofing filter and DSP are linked together. In other words, when you narrow the DSP to (and past) a certain point, the narrower roofing filter ALSO kicks in. This results in a poorly "controlled" experiment, ie, too many variables. Roofing filters work to help knock out IMD (intermod) which may be encountered when multiple, very strong signals (stronger than Mike's 59+10) populate the band. If you are hearing the station "next door" (in terms of frequency) on SSB interfering with your intended QSO, then you are NOT talking about something that a roofing is intended to prevent...that is the job of the final bandwidth (in the case of the K3, the DSP filtering). While it has been brought to light that there is a cascading effect of the multi-level filters, I find it hard to believe that you will run into more than a couple of situations per year (if that many) where you will appreciate the impact of using the 1.8kc roofing filter instead of the 2.1kc roofing filter for SSB. You will likely run into many situations per year where the DSP will work exactly as you wish. Again, I point to Mike's request, "I just dont want to hear a 59+10 signal that is 3 kc..from the frequency I am listening on." To me, this just screams DSP filter and NOT a narrower roofing filter. de Doug KR2Q _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
