Maximize the Peak !! I can't see the logic in modifying a circuit designed to "peak" and reduce the peaking ability so it flattens down and not peak so well with variable Q. Let it be an optimized Audio PEAK Filter like it is supposed to be ! It is a tool for CW guys. Use the DPB filter as suggested for casual CW dxing or maybe you don't need to use the APF at all ! I am not the only one that is using another radio in conjunction with their K3 for weak signal CW work just because of the APF. In the last Stew Perry contest on 160 I had my K3 and several other radios (IC-7600, FT1000, TS-930) in the receive line just for their APF. I could pull signals up out of the mud with these radios and make a contact. With the "unassisted" K3 I could copy only enough to know the signal was in the noise. The FT1000 has the most effective APF in the bunch. The K3 is an absolutely superb CW rig and an effective APF will make it walk on water !! The APF provides the specific peaking functionality tool needed on CW to dig out the tough ones. Please lets think in terms of optimizing ! ( It is a PEAKing filter)
addendum I am overjoyed at the prospect of having an APF in my K3. My hat is off to Elecraft for listening to us and implementing this super functionality! The sad thing for me will be to realize I no longer will need my old friends that I use just for their APF, Yaesu FT1000, Kenwood TS-930S (don't laugh the APF still works great in this oldie) and not so old IC-7600 (APF not as good as FT1000) Thanks Elecraft for listening to us ! Bob K6UJ On Nov 1, 2010, at 6:55 AM, Joe Subich, W4TV wrote: > >>> For some reason you keep thinking that Elecraft's APF is being >>> designed and programmed by Yaesu engineers.... > > No, I'm saying that there are significant reasons *not* to do > variable Q: > > 1) there is no available control. The "Width" control everyone > seems to want to use is already used in both the shift/width > and LO-CUT-HI modes. I for one, don't want to give up the > use of the Width control when APF is active. > > 2) reducing the Q will make APF much less effective as shown by > history with the FT-1000D. The later version of the FT-1000D > was ineffective compared to the original circuit in the 1000D > and FT-990. > > 3) The broader peaking (selectivity) of the MP/MK V contour circuit > so often cited as a prototype for "adjustable Q" is already > available using the existing Dual PB filter. > >>> I'm in favor of having a variable Q on this APF system. It will >>> help improve copy with a tight algorithm that Lyle has written >>> for this one, while at the same time allowing me to open the Q >>> so that I can copy not as weak signals with gain, and less >>> ringing. > > Ringing is a result of the selectivity and the fact that the APF > is implemented as an Infinite Impulse Response (IIR) filter. In > order to reduce the ringing you *MUST* reduce the selectivity and > that loss of selectivity will destroy the benefit of the APF. > > There is very little difference in absolute selectivity between 30 Hz > in the alpha APF and the 50 Hz minimum selectivity in the standard > DSP filters. Since even the 50 Hz DSP filter has a modest but > detectable ring, adding the ability to "de-Q" the APF would provide > no benefit that can't already be achieved using either the 50 Hz > DSP or Dual PB filters. > >>> I believe that Lyle will not destroy his own code by adding a >>> feature that Enhances the operation of what he's already created >>> for us. > > The whole point is that adding the ability to de-Q the APF will not > enhance its operation. It can only decrease its effectiveness and > reduce APF performance to something already available using existing > capabilities. > > In other words, if you want a filter with less ringing use the 50 Hz > or 100 Hz IIR DSP. If you want broad peaking with a wider background > use Dual PB. Use the correct tool for the job: don't try to use graft > a scalpel blade to an axe handle. > > 73, > > ... Joe, W4TV > > On 11/1/2010 4:24 AM, The Smiths wrote: >> >> Joe, >> >> For some reason you keep thinking that Elecraft's APF is being > designed and programmed by Yaesu engineers.... Why is it that just > because Yaesu made a mistake with their rig that it means Elecraft has > to destroy THEIR APF just because they choose to add an adjustable Q > control? You have to have confidence that the APF can remain exactly the > same as Lyle and the gang has written it while still adding the ability > to open it up some? Just because Yaesu programmers weren't talented > enough not to destroy what they had built doesn't mean that Elecraft > will make the same mistake. >> Furthermore there are Alpha testers like myself that will make sure > that once the variable Q has been put in that when set to the Minimum > (narrowest) setting that it will still act and feel like it does now. Of > course you too could do the same as an Alfa software tester. This isn't > Yaesu where no one listens to the users once they choose to make a > change or adjustment to the code... Your say WILL matter if things sound > different once the feature has been improved for others. I really don't > think that you're giving Elecraft, it's programmers, or the Alpha > testers such as myself enough credit. >> >> I'm in favor of having a variable Q on this APF system. It will help > improve copy with a tight algorithm that Lyle has written for this one, > while at the same time allowing me to open the Q so that I can copy not > as weak signals with gain, and less ringing. I believe that Lyle will > not destroy his own code by adding a feature that Enhances the operation > of what he's already created for us. If he does, I will be the first to > let him know so he can re-program it. >> The Dual pass band filter is nice, yes, but if you've used your DPB > filter in the K3 you know as well as I do that it acts NOTHING like the > APF with a wider Q in suppressing noise and improving gain as we're > seeing on this current APF. Again, this is NOT a Yaesu rig... >> >> >> >>> Date: Sun, 31 Oct 2010 10:27:33 -0400 >>> From: li...@subich.com >>> To: elecraft@mailman.qth.net >>> Subject: Re: [Elecraft] K3 APF Adjustable Q >>> >>> >>>>> however the fixed Q has a bit of ring and at times I would like to >>>>> back it off (widen) it just a tad. >>> >>> This is the same mistake Yaesu made in the FT-1000D; de-Qing the >>> original APF made it useless in later radios. This is the very >>> reason not to add adjustable Q or reduce the Q of the APF currently >>> in field test. If you want a less aggressive filter that is centered >>> on the sidetone, use Dual PB ... that's exactly what it is designed >>> to do (and it does a very good job when used as designed). >>> >>> Adjustable center frequency is very important ... particularly when >>> PB CTRL is set for Shift=.05 (to allow LO-CUT-HI to function) as >>> the 50 Hz increments too course to tune APF using the VFO. The user >>> also needs the ability to adjust the peak independently in order to >>> peak up an off frequency caller and not "chase them up the band." >>> >>> 73, >>> >>> ... Joe, W4TV >>> >>> >>> On 10/31/2010 8:58 AM, Steve Ellington wrote: >>>> If I had a choice between variable center frequency and adjustable Q, I >>>> would choose adjustable Q. >>>> >>>> My logic is: The center frequency automatically follows the sidetone >>>> frequency so I have no need to adjust it however the fixed Q has a bit of >>>> ring and at times I would like to back it off (widen) it just a tad. >>>> >>>> Otherwise it's a HUGE improvement, sounds great and I wish to thank those >>>> who made it possible. >>>> >>>> 73 >>>> N4LQ >>>> Steve >>>> >>>> ______________________________________________________________ >>>> 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 >> > ______________________________________________________________ > 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
