CW ops, especially those doing weak-signal DXing and DXpedition work, will now benefit from a second APF filter bandwidth in the K4. The original bandwidth is 30 Hz, which is good for code speeds up to about 30 WPM. The second bandwidth selection is 50 Hz, which allows copy up to about 50 WPM.
On the air, I'm finding this a great addition to the receiver toolbox, especially for close-spaced, fast CW contests. Adjacent signals just seem to disappear. APF has a narrow bandwidth only for the first several dB from its peak, then flares wider below that. This can dramatically improve S/N for weak signals right at the noise floor: it brings up the signal without "boxing up" band noise into a very narrow bandwidth. That's what causes ringing with "brick wall" filters. 73, Wayne N6KR ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
