Re: [Elecraft] K3 -Advice: how to configure APF for least ringing
I use APF only as a last resort, Robert. It can sometimes help me dig out and record very weak 10m beacons under QRM from adjacent beacons, with CW filters on turbo, sometimes also using the manual notch filter to try to kill the worst QRM. It takes time to peak the desired signal precisely on the nose of the APF, using the fine tuning setting, the CWT function and watching audio levels with the audio recording software (Audacity in my case). Beacons transmit continuously so there is no mad rush to get it set up. For regular DX QSOs, it's not worth the bother in my opinion, but as I recall the APF facility was introduced in response to requests from 160m DXers desperate to glean the faintest sniff of RF from the ionosphere. It does indeed ring. There is probably a physics lecturer desperate to tell us that ringing is an inevitable consequence of the very tight filtering, plus artifacts from the digital processing I guess. Ringing gets worse with fast CW but beacons tend to send quite slowly. 73 Gary ZL2iFB -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft- boun...@mailman.qth.net] On Behalf Of Robert G Strickland Sent: Saturday, 11 May 2013 11:46 a.m. To: Elecraft Subject: [Elecraft] K3 -Advice: how to configure APF for least ringing As a 98% cw operator, I've explored the various K3 weak signal features. I tend to shy away from the APF because its ringing seems to my ears to be counter productive. Any advice/experience on how to set up and use this feature for best results? Thanks. ...robert -- Robert G Strickland, PhD ABPH - KE2WY rc...@verizon.net.usa Syracuse, New York, USA __ 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 -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. __ 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
Re: [Elecraft] K3 -Advice: how to configure APF for least ringing
RobertG wrote I tend to shy away from the APF because its ringing seems to my ears to be counter productive. Any advice/experience on how to set up and use this feature for best results? If you don't use APF you're missing one of the best features of the K3 for weak signals. I now use it nearly 100% of the time for QRP SOTA stations on the higher bands or DX on 160m. There are two keys for me to using it effectively: 1. Back off RF Gain until the signal is at the noise floor. If you have too much signal, you'll definitely create ringing. 2. Use a relatively wide DSP/XFIL setting (e.g. I often use DSP=400 Hz with a 200 Hz XFIL, yes I set the 200 Hz XFIL to enable at 400 Hz instead of 200 Hz). In 160 contests, I sometimes use DSP=600 in a 500 Hz XFIL to better hear off-frequency callers). The relatively wider noise passband helps my ears distinguish signal from noise and APF then greatly improves this ability. 73, Bill W4ZV P.S. It goes without saying to carefully peak the APF on signal! (10 Hz steps maximum or even lower for extremely weak signals). -- View this message in context: http://elecraft.365791.n2.nabble.com/K3-Advice-how-to-configure-APF-for-least-ringing-tp7573557p7573568.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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] K3 -Advice: how to configure APF for least ringing
Best used when copy any other way is impossible due to a weak signal. Ringing is somewhat better than noise, isn't it? I've found APF useful in a number of QRP events, when handling weak signals is the order of the day. Yes - copy may be dificult but at least you have something to work with. APF is similar to Q-mulipliers we used in the 70's and earlier, prior to digital signal processing. By memory, the K3's (and KX3's) APF is an order of magnitude better than a Qmult. Imho, it is mainly due to the excellent DSP work by Lyle Johnson. Of course, some of the difference is also due to the relatively poor receivers we had back then. 73, matt W6NIA On Fri, 10 May 2013 23:46:24 +, you wrote: As a 98% cw operator, I've explored the various K3 weak signal features. I tend to shy away from the APF because its ringing seems to my ears to be counter productive. Any advice/experience on how to set up and use this feature for best results? Thanks. ...robert __ 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
Re: [Elecraft] K3 -Advice: how to configure APF for least ringing
I should have mentioned that APF is set the way it's set. I don't believe any parameters exist to change APF's operation. Someone may correct me on this. APF is best used with a narrow bandwidth setting. I think I saw the figure 30 Hz (for -6dB points) used in conjunction with APF, so a 50 or 100 Hz filter setting seems in order. That's what I use here. 73, matt W6NIA On Fri, 10 May 2013 17:33:35 -0700, you wrote: Best used when copy any other way is impossible due to a weak signal. Ringing is somewhat better than noise, isn't it? I've found APF useful in a number of QRP events, when handling weak signals is the order of the day. Yes - copy may be dificult but at least you have something to work with. APF is similar to Q-mulipliers we used in the 70's and earlier, prior to digital signal processing. By memory, the K3's (and KX3's) APF is an order of magnitude better than a Qmult. Imho, it is mainly due to the excellent DSP work by Lyle Johnson. Of course, some of the difference is also due to the relatively poor receivers we had back then. 73, matt W6NIA On Fri, 10 May 2013 23:46:24 +, you wrote: As a 98% cw operator, I've explored the various K3 weak signal features. I tend to shy away from the APF because its ringing seems to my ears to be counter productive. Any advice/experience on how to set up and use this feature for best results? Thanks. ...robert __ 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
Re: [Elecraft] K3 -Advice: how to configure APF for least ringing
I work mostly CW weak signal and have not heard ringing with the K3 .. Now I will say if you have your tones CW Pitch set at 800 Hz + or - it may sound like ringing to you , you might try lowering the CW Pitch say around 600 Hz or even lower Ed N5DG On 5/10/2013 7:36 PM, Matt Zilmer wrote: I should have mentioned that APF is set the way it's set. I don't believe any parameters exist to change APF's operation. Someone may correct me on this. APF is best used with a narrow bandwidth setting. I think I saw the figure 30 Hz (for -6dB points) used in conjunction with APF, so a 50 or 100 Hz filter setting seems in order. That's what I use here. 73, matt W6NIA On Fri, 10 May 2013 17:33:35 -0700, you wrote: Best used when copy any other way is impossible due to a weak signal. Ringing is somewhat better than noise, isn't it? I've found APF useful in a number of QRP events, when handling weak signals is the order of the day. Yes - copy may be dificult but at least you have something to work with. APF is similar to Q-mulipliers we used in the 70's and earlier, prior to digital signal processing. By memory, the K3's (and KX3's) APF is an order of magnitude better than a Qmult. Imho, it is mainly due to the excellent DSP work by Lyle Johnson. Of course, some of the difference is also due to the relatively poor receivers we had back then. 73, matt W6NIA On Fri, 10 May 2013 23:46:24 +, you wrote: As a 98% cw operator, I've explored the various K3 weak signal features. I tend to shy away from the APF because its ringing seems to my ears to be counter productive. Any advice/experience on how to set up and use this feature for best results? Thanks. ...robert __ 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 __ 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
Re: [Elecraft] K3 -Advice: how to configure APF for least ringing
I use 440 Hz and the APF almost full time, particularly for weak signal work. 73 Don K5AQ __ 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
Re: [Elecraft] K3 -Advice: how to configure APF for least ringing
Here's another approach to using APF on weak signals in an uncrowded band. - Turn on NR set to 5m3. You can play with this but 5m3 seems to work best here. - Set the DSP bandwidth to 1 KHz. This is a good way to search for weak signals you can't hear otherwise. The combination of NR and DSP BW drops the uncorrelated noise many dB. - Turn on the APF and carefully tune the signal to the peak of the APF passband. I typically use Spectrogram on a PC as a tuning aid throughout this whole process. - Ride the AF and RF gain controls to minimize the ringing affect Happy hunting! Brian, K0DTJ __ 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
