Unlike many other transceivers, ultimate selectivity in the K3 is not determined by the crystal filter. Ultimate selectivity is determined by the DSP whilst the roofing filter only impacts narrow band dynamic range (the level of "close in" signals applied to the second mixer and analog to digital converter [ADC]). In this case, the "roofing" filter sets the maximum bandwidth of the receive chain. See discussions by Elecraft here: http://www.elecraft.com/K3/Roofing_Filters.htm
My experience leads me to recommend the standard 2.7 KHz (5 pole) for SSB (based on the"exchange" price) with the added $130 spent on a 2.1 or 1.8 KHz filter if necessary. For CW and digital I would choose 400 Hz as the primary filter (the 500 Hz INRAD if one uses some of the 500 Hz wide MFSK based modes) and the 200 Hz 5 pole for critical CW (or possibly PSK31 and JT9) in the presence of strong adjacent signals. I don't see the need for a 1000 or 700 Hz filter as when conditions allow "wide" scanning, one of the SSB filters is generally sufficient in combination with DSP set to 1000/800/700 Hz. 73, ... Joe, W4TV On 8/6/2013 5:37 AM, [email protected] wrote:
I am about to purchase a K3 (k). My main interest is certainly CW with
occasional forays into SSB and even data, and I note the selection of roofing filters available, no doubt the 8-pole are somewhat better but what is the general feeling regarding the bandwidth(s) to be included.
Ivan G3IZD ______________________________________________________________ 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
______________________________________________________________ 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
