(BTW I wrote the following ~3 years ago before APF was changed from HOLD to TAP on DUAL PB):
############################################################## I use APF virtually all the time and never use RIT, SHIFT, etc. Just HOLD DUAL PB to actuate APF and use the VFO to zero beat. COARSE (10 Hz) VFO steps is usually close enough but you can switch to FINE (1 Hz) if necessary for ultra weak signals. I also strongly endorse N6KR's suggestion below: "I suggest setting the passband width to about 250-300 Hz when using APF." This is extremely important since bandwidths too narrow will introduce additional ringing to the APF which already borders on ringing. I actually use a 200 Hz XFIL but set to actuate at DSP 400 Hz. With WIDTH set to 400 Hz, the signal first goes through the relatively broad (4.0 shape factor) 200 Hz XFIL, then a 400 Hz DSP and finally the narrow APF. This makes the cascaded XFIL/DSP seem more like 250 Hz, reduces ringing, still allows you to hear off-frequency callers (although attenuated) and helps your ears discriminate weak signals from noise by providing a wider background sample of noise. ####################################################### The last phrase "helps your ears discriminate weak signals from noise by providing a wider background sample of noise" is key. Narrower bandwidths are not best for the human ear/brain...no matter what theory says about narrower bandwidths having better S/N. 73, Bill W4ZV -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-APF-and-selected-bandwidth-tp7623407p7623455.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ 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]
