APF For K3
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Paul,
I agree that the APF needs to have a high Q center frequency. This peaks the audio in a razor thin passband enabling a weak CW signal to be heard. A variable audio passband is needed as well as an adjustment for depth of peak. There is no feature on the K3 that can do the job better than a good APF function. From some of the comments I have read on this reflector I do not believe many hams are familiar with this feature. Those who primarily use CW would find APF highly desirable. Roy Morris W4WFB ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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I used APF in the past on CW contacts when needed. This feature seems to have been lost on some of todays modern radios. Because I haven't pounded the brass as much as I used to, I had forgotten about this wonderful APF feature. Those of us who have used it on CW know how really great this feature is. Weak CW signals that are unreadable are enhanced with APF making some QRP contacts possible that otherwise wouldn't be heard. Wayne has said he is putting this feature on the K3 list. I am thrilled that Elecraft is considering this feature. I am looking forward to having APF on my K3s. Roy Morris W4WFB
______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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guess I will be brave, step up, assume the dummy position,
and ask the obvious question.... what the heck is APF Animal Protective Foundation Advanced Protection Formula American Pain Foundation pick one: http://acronyms.thefreedictionary.com/APF signed clueless GB & 73 K5OAI Sam Morgan On 10/24/2010 10:43 AM, Roy Morris wrote: > I used APF in the past on CW contacts when needed. This feature seems to > have been lost on some of todays modern radios. Because I haven't pounded > the brass as much as I used to, I had forgotten about this wonderful APF > feature. Those of us who have used it on CW know how really great this > feature is. Weak CW signals that are unreadable are enhanced with APF making > some QRP contacts possible that otherwise wouldn't be heard. Wayne has said > he is putting this feature on the K3 list. I am thrilled that Elecraft is > considering this feature. I am looking forward to having APF on my K3s. Roy > Morris W4WFB ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Roy Morris-6
Audio peak Filter
-Bruce N1RX ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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isn't that kind of what the CWT
or any cw decoding software does when decoding? GB & 73 K5OAI Sam Morgan On 10/24/2010 11:04 AM, Bruce Beford wrote: > Audio peak Filter > -Bruce N1RX > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Roy Morris-6
Sam wrote:
> isn't that kind of what the CWT > or any cw decoding software > does when decoding? > GB & 73 > K5OAI > Sam Morgan Not exactly. My understanding is that an audio peaking filter actually boosts or accentuates the audio at a particular frequency, rather than attenuating those at other frequencies. It's function is to enhance one thing, rather than reduce other things. It's all in the semantics, I suppose... 73, Bruce N1RX ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Bruce Beford-2
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This may be a reasonable representation of the concept ?
http://www.ab4oj.com/icom/ic7600/apf.html ~Iain / N6ML On Sun, Oct 24, 2010 at 4:55 PM, Ron D'Eau Claire <[hidden email]> wrote: > According to Icom (who has it on some of their rigs): > > "The APF changes the audio frequency response by > boosting a particular frequency to enhance a desired > CW signal... The peak frequency can be adjusted" > > So this is an adjustable frequency audio filter such as we've used for the > past 3/4 century. > > As Doug, KR2Q, noted, the K3 is capable of a 50 Hz bandpass. That's about as > narrow as a CW signal being keyed at 20 or 30 wpm can be fit into. Narrower > will attenuate the CW sidebands so the dots and dashes start "slurring" > together. > > I've used an audio filter many times and found them of very limited value to > me if the receiver has a decent I.F. bandpass characteristic. > > That said, if it it's reasonable to implement, people want it, and it can be > switched out, I'm all for it. > > Ron AC7AC > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Bruce Beford-2
Seems to me that adjusting the "Pitch" to one that most comfortably
stands out from others and then using "Spot" ought to accomplish the same thing. No? -- 73, Dick KA1OZ Middleborough, MA Radio: Elecraft K3/100(Kit) SN 859 Antenna: Titan-DX Bruce Beford wrote: > Sam wrote: > >> isn't that kind of what the CWT >> or any cw decoding software >> does when decoding? > >> GB& 73 >> K5OAI >> Sam Morgan > > Not exactly. My understanding is that an audio peaking filter actually > boosts or accentuates the audio at a particular frequency, rather than > attenuating those at other frequencies. It's function is to enhance one > thing, rather than reduce other things. It's all in the semantics, I > suppose... > > 73, > Bruce N1RX > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Apparently not. Some with experience with other radio's implementation of an
APF function say that the currently available filtration offerings on the K3 are not equivalent. As the link recently posted for Adam Farson's page on the Icom APF shows, an APF can roll off the adjacent frequencies, rather than having a flat pass-band, at whatever width. Like all audio enhancement, it's a rather subjective thing. Bruce, N1RX (Not an avid APF cheerleader, but I -do- like having many filtering options). -----Original Message----- From: Dick Roth, KA1OZ [mailto:[hidden email]] Sent: Sunday, October 24, 2010 1:45 PM To: Bruce Beford Cc: [hidden email] Subject: Re: [Elecraft] APF For K3 Seems to me that adjusting the "Pitch" to one that most comfortably stands out from others and then using "Spot" ought to accomplish the same thing. No? -- 73, Dick KA1OZ Middleborough, MA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Roy Morris-6
I have found that using the receive EQ for this works quite nicely. I raise the frequency matching that of my side-tone and attenuate all others. The K3 will automatically switch to this EQ setting when you enable the CW mode and switch to the SSB setting when that mode is enabled.
Good luck, Mike N8XPQ |
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In reply to this post by raroth7
No, actually not.
The MP has something "like" APF, without calling it that. On CW if you turn on EDSP and set contour to 11 oclock and set NR to D and then set spot to 450, what you will get is a rounded AF response. This works well running (as opposed to search and pounce) in a contest, when you want to hear up and down a ways to catch the off-frequency callers (seemingly about 25% of world population, equals entirely common, typical tone-deaf to some degree), but don't want the entire bandwidth of noise roaring in your ear. At this point, I have no means of duplicating that in the K3. This is NOT the same as running narrower bandwidth. If I narrow bandwidth, then I don't hear the off-frequency callers, some of which are closer to the up or down stations than me. Throwing away up and down callers easily throws away 10% of run QSO's depending on how tight you have to squeeze. This is why I have the "250" roofing filter defined as 350 with the 400 defined as 450. I will run at 450 if I can get away with it. When it gets crowded, 350 running is really as tight as I want to go, just so I can hear off-frequency callers. I just need to hear them well enough to get them in with shift or RIT. 450 with APF is having your cake and eating it too. For that matter, if Wayne sees this, a fixed to center mild NR-generated APF that came out like the MP version but with an automatic band-pass following center might be a big hit. Try the above with an MP some time and see if you can mimmick that in K3 firmware. Once discovered, it was always a favorite. That's where I got stuck on 450 Hz as a center frequency. Just got used to it. I don't hate my MP. I just wish to H* that it had a K3 style uncrushable RF IF string. Yes, APF, and sooner than later, and with a scalar adjustment to how deep it goes and the width. 73, Guy. On Sun, Oct 24, 2010 at 1:45 PM, Dick Roth, KA1OZ <[hidden email]> wrote: > Seems to me that adjusting the "Pitch" to one that most comfortably > stands out from others and then using "Spot" ought to accomplish the > same thing. No? > > -- > 73, > Dick KA1OZ > Middleborough, MA > > Radio: Â Elecraft K3/100(Kit) SN 859 > Antenna: Â Titan-DX > Bruce Beford wrote: >> Sam wrote: >> >>> isn't that kind of what the CWT >>> or any cw decoding software >>> does when decoding? >> >>> GB& Â 73 >>> K5OAI >>> Sam Morgan >> >> Not exactly. My understanding is that an audio peaking filter actually >> boosts or accentuates the audio at a particular frequency, rather than >> attenuating those at other frequencies. Â It's function is to enhance one >> thing, rather than reduce other things. It's all in the semantics, I >> suppose... >> >> 73, >> Bruce N1RX >> >> >> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> 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:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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The only radio I found APF extremely useful was my FT1000D. It could pull essentially inaudible signals out of the noise on 80 and 160. I believe Yaesu modified and broke the APF in later 1000D's, and there was a mod to resurrect it. I found the APF in my Icom 7800 worthless.
IMO, implemented the right way, as in the early 1000D's, it would be a useful feature. Barry W2UP |
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> I found the APF in my Icom 7800 worthless.
Same here. Icom's implementation of APF in the '7700/'7800 is really an "Audio Passband Filter" with low Q. It's really no different than narrowing a DSP passband filter. What's unique about the FT-1000D's APF is that the Q is very high, although its affected with APF tuning. The high Q of the circuit forms a very narrow filter with fixed gain, and variable peaking frequency. Paul, W9AC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Guy, K2AV
Shortly after the K3 appeared on the scene three years ago, those of us
who had gotten used to (and enamored of) the APF in the FT-1000D lobbied for such a circuit in the K3. As I understand it, the Yaesu SCAF circuit was studied, but nothing ever came of it. Software-defined radios are radically different from analog ones, as we all know. Every once in a while I'll fire up the 1000D and appreciate all over again the effectiveness of its APF. 73, Kent K9ZTV ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by P.B. Christensen
I found the "AF Tune" peaking function in the old Kenwood TS930 to be
quite useful. Is that similar to the desired implementation or was it something different? 73, Bob K2TK On 10/24/2010 2:47 PM, Paul Christensen wrote: >> I found the APF in my Icom 7800 worthless. >> > Same here. Icom's implementation of APF in the '7700/'7800 is really an > "Audio Passband Filter" with low Q. It's really no different than narrowing > a DSP passband filter. > > What's unique about the FT-1000D's APF is that the Q is very high, although > its affected with APF tuning. The high Q of the circuit forms a very narrow > filter with fixed gain, and variable peaking frequency. > > Paul, W9AC > > > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by P.B. Christensen
I have never used a receiver with a button labeled APF, but I have
used my K2 with an audio filter. It seems to me the only other characteristic of APF is that the center frequency can be changed. On the K3, we have the Dual Passband that may work in a similar manner. Set the width to the lowest value 50 Hz and turn on Dual PB and you have a wide filter with a peak at your sidetone pitch. You can change the Pitch if you wish to peak a different audio frequency, but for the life of me, I cannot imagine why anyone would want to peak any pitch other than his preferred sidetone pitch. If you want a little more peaking, turn on NR and set it to an aggressive setting. The way NR works is that it builds a narrow filter around a signal that it thinks is a valid signal - so you have a filter at the audio pitch where you have set the VFO. Yes, the K3 is different than those receiver that have APF, but in my opinion, it accomplishes the same thing, but differently. 73, Don W3FPR On 10/24/2010 2:47 PM, Paul Christensen wrote: >> I found the APF in my Icom 7800 worthless. > Same here. Icom's implementation of APF in the '7700/'7800 is really an > "Audio Passband Filter" with low Q. It's really no different than narrowing > a DSP passband filter. > > What's unique about the FT-1000D's APF is that the Q is very high, although > its affected with APF tuning. The high Q of the circuit forms a very narrow > filter with fixed gain, and variable peaking frequency. > > Paul, W9AC > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Bob-270
On Oct 24, 2010, at 2:59 PM, Bob wrote: > I found the "AF Tune" peaking function in the old Kenwood TS930 to be > quite useful. I'm generally not a fan of using audio peaking filters (in my early years of hamming, I spent too much time listening on receivers that had audio filters instead of adequate IF filtering), but I grudgingly thought the APF on my TS-940 made the difference between readability or not in certain weak signal situations on 160 and 80. Despite its DSP-based audio contouring, I've missed having an APF on my TS-950SDX (over a many-year period) and I'm thinking I wouldn't mind having a tunable APF on my K3 (which I've had for only a few weeks) as well. Bud, W2RU ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Bruce Beford-2
kinda reminds me of the q multiplier I had on the old Drake 2B. That thing
was unbelievable at bringing cw signals out of the soup. Lou WA3MIX ----- Original Message ----- From: "Bruce Beford" <[hidden email]> To: <[hidden email]> Cc: <[hidden email]> Sent: Sunday, October 24, 2010 2:10 PM Subject: Re: [Elecraft] APF For K3 > Apparently not. Some with experience with other radio's implementation of > an > APF function say that the currently available filtration offerings on the > K3 > are not equivalent. > > As the link recently posted for Adam Farson's page on the Icom APF shows, > an > APF can roll off the adjacent frequencies, rather than having a flat > pass-band, at whatever width. Like all audio enhancement, it's a rather > subjective thing. > > Bruce, N1RX > > (Not an avid APF cheerleader, but I -do- like having many filtering > options). > > -----Original Message----- > From: Dick Roth, KA1OZ [mailto:[hidden email]] > Sent: Sunday, October 24, 2010 1:45 PM > To: Bruce Beford > Cc: [hidden email] > Subject: Re: [Elecraft] APF For K3 > > Seems to me that adjusting the "Pitch" to one that most comfortably > stands out from others and then using "Spot" ought to accomplish the > same thing. No? > > -- > 73, > Dick KA1OZ > Middleborough, MA > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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My guess is that Q-multiplier was in the IF.
The old HeathKit QF-1s were at 455KHz. For best functionality (and maximum difficulty?) this peaking function would work best withing the AGC loop at IF. At AF, it won't do a lot of good if you have another nearby, within pass band signal pumping the AGC. 73 de Brian/K3KO On 10/24/2010 19:38, Lou Kolb wrote: > kinda reminds me of the q multiplier I had on the old Drake 2B. That thing > was unbelievable at bringing cw signals out of the soup. Lou WA3MIX > ----- Original Message ----- > ----- No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1144 / Virus Database: 422/3216 - Release Date: 10/24/10 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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