Ed, If there are no strong signals on the band or nearby your receive frequency, then any filter, even the stock 2.7 kHz is sufficient. The only purpose of the roofing filter is to keep strong signals out of the receiver passband so they do not activate the AGC and de-sense the receiver for the signal you are trying to hear.
73, Don W3FPR On 2/9/2011 3:07 AM, Edward R. Cole wrote: > Let me ask a filter question for a different situation. I am > interested in receiving very-weak CW and currently have the 2.8 KHz > and 400-Hz 8-pole filters. Will narrowing the DSP bw down to 200-Hz > work as well as using a 200-Hz filter? There are no strong stations > either nearby or on the band. > > BTW I am impressed with the 400-Hz filter on the K3 when compared to > the 400-Hz DSP on my FT-847 (no surprise). > I find trying to hear extremely weak-CW that narrowing down to 200, > 100 or even narrower makes the difference. > > I left a blank filter space on the main receive for adding a narrow > SSB filter at a later time. I also have the 13-KHz filter for > FM/AM. Sub-Rx has 2.8 and 13-KHz. > > ______________________________________________________________ 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
