I've seen it written that it helps to offset the IF slightly, although to be honest I have never myself got the APF to work to my satisfaction. Oddly, and I communicated with Wayne about this at the time, the first beta (I think) implementation of it was stunning, but a later release lost it for me. Wayne told me there had been no change in code, but I have never understood that. With my XYL away in London for the weekend, I might devote some more time to it :-)
73 Stephen G4SJP On 5 February 2016 at 15:27, David Kuechenmeister <n...@bellsouth.net> wrote: > Thanks. I'll try again and be very careful this time. > vy 73,Dave N4KD > > On Friday, February 5, 2016 10:08 AM, Barry N1EU <n1eu.ba...@gmail.com> > wrote: > > > The receiver has to be tuned precisely to the signal in question for APF > to > work. > > 73, Barry N1EU > > On Fri, Feb 5, 2016 at 9:53 AM, David Kuechenmeister <n...@bellsouth.net> > wrote: > > > I tried this the other day with no success. That is, the weak signal that > > was barely detectable, became so buried in ringing that I couldn't detect > > it at all. I think I followed the procedure outlined in Wayne's email > > below... > > Noise was around S5 on 40m and the K3 was configured with APF active. I > > had my 500 Hz filter selected and varied the DSP WIDTH from 500 to 300 > > without substantial improvement. FINE tuning selected. > > What am I forgetting? > > vy 73,Dave N4KD > > > > On Tuesday, February 2, 2016 9:36 AM, Wayne Burdick < > n...@elecraft.com> > > wrote: > > > > > > Hi all, > > > > This morning I was hearing lots of very weak signals in the 40-meter CW > > band, right at today's noise floor of about S-5. (Among others, I copied > > BG4GOV in Shanghai.) > > > > Many of the signals were not copyable until I turned on APF (audio > peaking > > filter). This filter's center peak is very narrow (around 30 Hz), but the > > response broadens out quickly below the 3-dB points in the curve. This > > brings up the desired signal without allowing noise to cause > > ringing--something often heard with narrow filters of the "brick-wall" > > variety. On a noisy band, the effect is just short of magic. > > > > APF is very narrow, so you'll need to tune in 1-Hz increments when it is > > turned on. Also, APF works best when used with a DSP/crystal filter WIDTH > > setting of 300-500 Hz. > > > > Use of APF differs for the three transceivers. > > > > KX3: 1-Hz tuning is selected automatically on the when the APF switch is > > pressed. > > > > K3/K3S: APF is accessed via a hold of the XFIL switch. This function is > > labeled "APF" on a K3S, or "DUAL PB" on the K3). Use CONFIG:DUAL PB to > make > > sure the selected filter function is APF. See the K3/K3S owner's manual > for > > a description of the alternate setting. 1-Hz tuning can be selected by > > tapping FINE. > > > > You might want to give APF a try if you haven't already. > > > > 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 n...@bellsouth.net > > > > > > > > ______________________________________________________________ > > 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 n1eu.ba...@gmail.com > > > ______________________________________________________________ > 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 n...@bellsouth.net > > > > ______________________________________________________________ > 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 eastbrantw...@gmail.com ______________________________________________________________ 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
