K3 Audio
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Hi Joe,
no - Winrad was in "both channels - R+L" mode, no I/Q. AFX is off. How the output is if I/Q input choosed to test how it looks you can see on http://www.ok1kei.org/K3_audio/line_out_IQ.JPG This is quite different. 73! L. -dst- Joe Subich, W4TV napsal(a): > Do you have AFX "on" and are you looking at I/Q (left/right) from > the K3? The capture - including the small "spike" directly between > the "real" and "ghost" signals looks like you are trying to process > an unbalanced I/Q signal with the resulting improperly nulled image. > > 73, > > ... Joe, W4TV > > > > >> -----Original Message----- >> From: [hidden email] >> [mailto:[hidden email]] On Behalf Of >> Alexandr Kobranov >> Sent: Wednesday, August 06, 2008 5:53 PM >> Cc: 'elecraft Reflector' >> Subject: Re: [Elecraft] Re: K3 Audio >> >> >> I just made two basic samples using K3 and TS-850 using Firebox >> external soundcard and Winrad SW. >> >> You can see screenshot from K3 line-out audio on >> >> http://www.ok1kei.org/K3_audio/line_out_firebox_winrad.jpg >> >> This is K3 with 400Hz roofing filter on some stable carrier. >> LINE OUT setting on level 9. >> >> Then the same signal with the same af level (no change in Firebox >> input mixer settings) with TS-850 >> >> http://www.ok1kei.org/K3_audio/ts850_af_firebox_winrad.jpg >> >> This is my TS-850 with 400Hz inrad filter and output from >> phones jack. There are also some "ghosts" in af spectrum, >> generaly more noisy, but >> no "image" of passband af signal visible. >> >> As I do not believe in overloding of the Firebox soundcard (the same >> conditions for both RIGs so if overloded so in both cases...), there >> is something to explain. >> >> Comments? >> >> Thanks for your attention, >> 73! >> Lexa, OK1DST >> K3/10 #727 >> >> >> >> >> Alexandr Kobranov napsal(a): >>> I can confirm cca 20dB lower level of 3rd harmonics on front panel >>> phones output against rear panel line out. Main versus 3rd >> harmonics is >>> 50dB resp. 7OdB on line-out resp. phones output here. >>> Just tried with on-board sound card od my Dell workstation. >>> (using Spectran SW and output level adjusted for the same >> peak out level >>> on Spectran screen). >>> Maybe later will try with Firebox sound card which has >> better parameters. >>> Lexa, ok1dst >>> >>> Joe Subich, W4TV napsal(a): >>>>> There is still a bit of a problem on receive audio. This has been >>>>> there for some time and exists in the form of harmonics. The 3rd >>>>> harmonic is quite easy to see and repeatable. I used HRD to show >>>>> this on the waterfall after a conversation with a friend. You can >>>>> clearly see the harmonic at.. >>>> You are overdriving your sound card or the line out transformer in >>>> the >>>> K3. >>>> I have measured the third harmonic using an audio spectrum analyzer >>>> at both the line out and headphone jacks of my K3. Until >> the level >>>> becomes excessive (> .7V RMS on the Line Out) the third >> harmonic is >>>> more than 50 dB down (Line Out) and more than 70 dB down >> (headphones). >>>> 73, >>>> ... Joe, W4TV >>>> > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Alexandr Kobranov
Could you try this test again and just turn down your RF gain a bit?
Or try turning down your AGC threshold. I found that if your an automatic kinda guy that a threshold of 2 with a slope of 10 works pretty good. I found that when listening to a CW station if the AGC was threshold was set to high and the RF gain was maxed out that I did get a lot of harmonic distortion. I found that turning down the RF gain helped a little bit but once you hit a certain point poof most of it goes away. It seems like there is a stage being driven into clipping even before the audio and thats where the harmonics are coming from. Even from the two previous recordings that I did where I preferred the K1 because the narrower filter settings sounded very harsh on the ears well it just so turns out that some better AGC settings (or simply turning the RF gain down) results in a MUCH more pleasant sounding rig. Another one of those places where the ultimate adjustibility of the K3 caused me some grief but I learned something about the rig and had fun with the hobby so still yet color me happy! Hope the rest of you are having as much fun finding and figuring out things as I... :) New K3 tagline..... Elecraft K3.... Its not an appliance! ~Brett (KC7OTG) On Wed, 2008-08-06 at 23:53 +0200, Alexandr Kobranov wrote: > I just made two basic samples using K3 and TS-850 using Firebox > external soundcard and Winrad SW. > > You can see screenshot from K3 line-out audio on > > http://www.ok1kei.org/K3_audio/line_out_firebox_winrad.jpg > > This is K3 with 400Hz roofing filter on some stable carrier. > LINE OUT setting on level 9. > > Then the same signal with the same af level (no change in Firebox > input mixer settings) with TS-850 > > http://www.ok1kei.org/K3_audio/ts850_af_firebox_winrad.jpg > > This is my TS-850 with 400Hz inrad filter and output from phones jack. > There are also some "ghosts" in af spectrum, generaly more noisy, but > no "image" of passband af signal visible. > > As I do not believe in overloding of the Firebox soundcard (the same > conditions for both RIGs so if overloded so in both cases...), there > is something to explain. > > Comments? > > Thanks for your attention, > 73! > Lexa, OK1DST > K3/10 #727 > > > > > Alexandr Kobranov napsal(a): > > I can confirm cca 20dB lower level of 3rd harmonics on front panel > > phones output against rear panel line out. Main versus 3rd harmonics is > > 50dB resp. 7OdB on line-out resp. phones output here. > > Just tried with on-board sound card od my Dell workstation. > > (using Spectran SW and output level adjusted for the same peak out level > > on Spectran screen). > > Maybe later will try with Firebox sound card which has better parameters. > > Lexa, ok1dst > > > > Joe Subich, W4TV napsal(a): > >> > >>> There is still a bit of a problem on receive audio. This has been > >>> there for some time and exists in the form of harmonics. The 3rd > >>> harmonic is quite easy to see and repeatable. I used HRD to show > >>> this on the waterfall after a conversation with a friend. You can > >>> clearly see the harmonic at.. > >> > >> You are overdriving your sound card or the line out transformer in the > >> K3. > >> I have measured the third harmonic using an audio spectrum analyzer > >> at both the line out and headphone jacks of my K3. Until the level > >> becomes excessive (> .7V RMS on the Line Out) the third harmonic is > >> more than 50 dB down (Line Out) and more than 70 dB down (headphones). > >> 73, > >> ... Joe, W4TV > >> > >> _______________________________________________ > >> Elecraft mailing list > >> Post to: [hidden email] > >> You must be a subscriber to post to the list. > >> Subscriber Info (Addr. Change, sub, unsub etc.): > >> http://mailman.qth.net/mailman/listinfo/elecraft > >> Help: http://mailman.qth.net/subscribers.htm > >> Elecraft web page: http://www.elecraft.com > >> > > _______________________________________________ > > Elecraft mailing list > > Post to: [hidden email] > > You must be a subscriber to post to the list. > > Subscriber Info (Addr. Change, sub, unsub etc.): > > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > > Elecraft web page: http://www.elecraft.com > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hi Brett,
yes, I can play with it today evening I hope. Now having AGC-F, SLP 13 and TRSHLD 6, RF MAX On TS-850 I have AGC Fast, RF max All testing on relatively strong signals(more then S7). But I am not sure possible if "clipping" is before final AF output as there are differencies between LINE OUT and PHONES output. But who knows... Generally having some "leakage" -50dB and 3f out of desired signal is not seriuos problem for CW/SSB (imho), maybe only for us we use af out for some post-processing (Spectran, Winrad,...) or digital decoder (PSK, WSJT, WSPR, CW Skimmer,...) can such "ghosts" make some confusions. Not sure if there can be problem with weak digital signals like WSJT (but decoding K2UYH on 23cm some week ago without any problems and shortly tested WSPR on 30m band and no problems od decoder recognized also). Maybe all this is more academic but still interesting :-) Maybe somebody else can report more serious problems with this phenomena, I am not using digital modes intensively. As I am leaving for holiday I am afraid I will not be able to make more tests/screenshots during next days - maybe somebody else can spend next weekend with some testing :-) (But taking my K3 and some "HF wires" with - surely :-)) 73! Lexa, ok1dst K3/10 #727 Brett Howard napsal(a): > Could you try this test again and just turn down your RF gain a bit? > > Or try turning down your AGC threshold. I found that if your an > automatic kinda guy that a threshold of 2 with a slope of 10 works > pretty good. > > I found that when listening to a CW station if the AGC was threshold was > set to high and the RF gain was maxed out that I did get a lot of > harmonic distortion. I found that turning down the RF gain helped a > little bit but once you hit a certain point poof most of it goes away. > It seems like there is a stage being driven into clipping even before > the audio and thats where the harmonics are coming from. > > Even from the two previous recordings that I did where I preferred the > K1 because the narrower filter settings sounded very harsh on the ears > well it just so turns out that some better AGC settings (or simply > turning the RF gain down) results in a MUCH more pleasant sounding rig. > Another one of those places where the ultimate adjustibility of the K3 > caused me some grief but I learned something about the rig and had fun > with the hobby so still yet color me happy! > > Hope the rest of you are having as much fun finding and figuring out > things as I... :) > > New K3 tagline..... > > Elecraft K3.... Its not an appliance! > > ~Brett (KC7OTG) > > > On Wed, 2008-08-06 at 23:53 +0200, Alexandr Kobranov wrote: >> I just made two basic samples using K3 and TS-850 using Firebox >> external soundcard and Winrad SW. >> >> You can see screenshot from K3 line-out audio on >> >> http://www.ok1kei.org/K3_audio/line_out_firebox_winrad.jpg >> >> This is K3 with 400Hz roofing filter on some stable carrier. >> LINE OUT setting on level 9. >> >> Then the same signal with the same af level (no change in Firebox >> input mixer settings) with TS-850 >> >> http://www.ok1kei.org/K3_audio/ts850_af_firebox_winrad.jpg >> >> This is my TS-850 with 400Hz inrad filter and output from phones jack. >> There are also some "ghosts" in af spectrum, generaly more noisy, but >> no "image" of passband af signal visible. >> >> As I do not believe in overloding of the Firebox soundcard (the same >> conditions for both RIGs so if overloded so in both cases...), there >> is something to explain. >> >> Comments? >> >> Thanks for your attention, >> 73! >> Lexa, OK1DST >> K3/10 #727 >> >> >> >> >> Alexandr Kobranov napsal(a): >>> I can confirm cca 20dB lower level of 3rd harmonics on front panel >>> phones output against rear panel line out. Main versus 3rd harmonics is >>> 50dB resp. 7OdB on line-out resp. phones output here. >>> Just tried with on-board sound card od my Dell workstation. >>> (using Spectran SW and output level adjusted for the same peak out level >>> on Spectran screen). >>> Maybe later will try with Firebox sound card which has better parameters. >>> Lexa, ok1dst >>> >>> Joe Subich, W4TV napsal(a): >>>>> There is still a bit of a problem on receive audio. This has been >>>>> there for some time and exists in the form of harmonics. The 3rd >>>>> harmonic is quite easy to see and repeatable. I used HRD to show >>>>> this on the waterfall after a conversation with a friend. You can >>>>> clearly see the harmonic at.. >>>> You are overdriving your sound card or the line out transformer in the >>>> K3. >>>> I have measured the third harmonic using an audio spectrum analyzer >>>> at both the line out and headphone jacks of my K3. Until the level >>>> becomes excessive (> .7V RMS on the Line Out) the third harmonic is >>>> more than 50 dB down (Line Out) and more than 70 dB down (headphones). >>>> 73, >>>> ... Joe, W4TV >>>> >>>> _______________________________________________ >>>> Elecraft mailing list >>>> Post to: [hidden email] >>>> You must be a subscriber to post to the list. >>>> Subscriber Info (Addr. Change, sub, unsub etc.): >>>> http://mailman.qth.net/mailman/listinfo/elecraft >>>> Help: http://mailman.qth.net/subscribers.htm >>>> Elecraft web page: http://www.elecraft.com >>>> >>> _______________________________________________ >>> Elecraft mailing list >>> Post to: [hidden email] >>> You must be a subscriber to post to the list. >>> Subscriber Info (Addr. Change, sub, unsub etc.): >>> http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/subscribers.htm >>> Elecraft web page: http://www.elecraft.com >>> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I'm pretty much mostly a CW op and I find that making sure that I don't
get too high in the RF gains to be important as I found that the sound is a LOT harsher when you are in this area. It definitely sounds like clipping and now that I've looked at it it looks like it too. Also I found that I ran into this issue more often when I was using the narrower filters. Well I found that the filter setup that I had on my rig when it came back from repair was to have a +7dB gain on my 250Hz filter. I went in and later fooled around with those and setup my 250Hz filter to kick in around 350 or so and that is about where I started to notice this get a little worse. But once I started going to wider filters not only did that turn down the gain a bit but it also opened things up so that it was a bit harder to see the harmonic spurs. Anyway I'm glad that you started posting your pics as it made me start to look at things using baudline and after looking at my recordings and fiddling with the radio for a bit I've got things sounding MUCH better. I should also note that my line out setting was at 5 when I was doing my tests and I find that to be more than enough signal to keep the sound card happy. Thanks much... ~Brett On Thu, 2008-08-07 at 11:09 +0200, Alexandr Kobranov wrote: > Hi Brett, > > yes, I can play with it today evening I hope. > Now having AGC-F, SLP 13 and TRSHLD 6, RF MAX > On TS-850 I have AGC Fast, RF max > All testing on relatively strong signals(more then S7). > > But I am not sure possible if "clipping" is before final AF output as > there are differencies between LINE OUT and PHONES output. But who > knows... > > Generally having some "leakage" -50dB and 3f out of desired signal is > not seriuos problem for CW/SSB (imho), maybe only for us we use af out > for some post-processing (Spectran, Winrad,...) or digital decoder > (PSK, WSJT, WSPR, CW Skimmer,...) can such "ghosts" make some confusions. > Not sure if there can be problem with weak digital signals like WSJT > (but decoding K2UYH on 23cm some week ago without any problems and > shortly tested WSPR on 30m band and no problems od decoder recognized > also). > Maybe all this is more academic but still interesting :-) > Maybe somebody else can report more serious problems with this > phenomena, I am not using digital modes intensively. > > As I am leaving for holiday I am afraid I will not be able to make > more tests/screenshots during next days - maybe somebody else can > spend next weekend with some testing :-) > (But taking my K3 and some "HF wires" with - surely :-)) > > 73! > Lexa, ok1dst > K3/10 #727 > > Brett Howard napsal(a): > > Could you try this test again and just turn down your RF gain a bit? > > > > Or try turning down your AGC threshold. I found that if your an > > automatic kinda guy that a threshold of 2 with a slope of 10 works > > pretty good. > > > > I found that when listening to a CW station if the AGC was threshold was > > set to high and the RF gain was maxed out that I did get a lot of > > harmonic distortion. I found that turning down the RF gain helped a > > little bit but once you hit a certain point poof most of it goes away. > > It seems like there is a stage being driven into clipping even before > > the audio and thats where the harmonics are coming from. > > > > Even from the two previous recordings that I did where I preferred the > > K1 because the narrower filter settings sounded very harsh on the ears > > well it just so turns out that some better AGC settings (or simply > > turning the RF gain down) results in a MUCH more pleasant sounding rig. > > Another one of those places where the ultimate adjustibility of the K3 > > caused me some grief but I learned something about the rig and had fun > > with the hobby so still yet color me happy! > > > > Hope the rest of you are having as much fun finding and figuring out > > things as I... :) > > > > New K3 tagline..... > > > > Elecraft K3.... Its not an appliance! > > > > ~Brett (KC7OTG) > > > > > > On Wed, 2008-08-06 at 23:53 +0200, Alexandr Kobranov wrote: > >> I just made two basic samples using K3 and TS-850 using Firebox > >> external soundcard and Winrad SW. > >> > >> You can see screenshot from K3 line-out audio on > >> > >> http://www.ok1kei.org/K3_audio/line_out_firebox_winrad.jpg > >> > >> This is K3 with 400Hz roofing filter on some stable carrier. > >> LINE OUT setting on level 9. > >> > >> Then the same signal with the same af level (no change in Firebox > >> input mixer settings) with TS-850 > >> > >> http://www.ok1kei.org/K3_audio/ts850_af_firebox_winrad.jpg > >> > >> This is my TS-850 with 400Hz inrad filter and output from phones jack. > >> There are also some "ghosts" in af spectrum, generaly more noisy, but > >> no "image" of passband af signal visible. > >> > >> As I do not believe in overloding of the Firebox soundcard (the same > >> conditions for both RIGs so if overloded so in both cases...), there > >> is something to explain. > >> > >> Comments? > >> > >> Thanks for your attention, > >> 73! > >> Lexa, OK1DST > >> K3/10 #727 > >> > >> > >> > >> > >> Alexandr Kobranov napsal(a): > >>> I can confirm cca 20dB lower level of 3rd harmonics on front panel > >>> phones output against rear panel line out. Main versus 3rd harmonics is > >>> 50dB resp. 7OdB on line-out resp. phones output here. > >>> Just tried with on-board sound card od my Dell workstation. > >>> (using Spectran SW and output level adjusted for the same peak out level > >>> on Spectran screen). > >>> Maybe later will try with Firebox sound card which has better parameters. > >>> Lexa, ok1dst > >>> > >>> Joe Subich, W4TV napsal(a): > >>>>> There is still a bit of a problem on receive audio. This has been > >>>>> there for some time and exists in the form of harmonics. The 3rd > >>>>> harmonic is quite easy to see and repeatable. I used HRD to show > >>>>> this on the waterfall after a conversation with a friend. You can > >>>>> clearly see the harmonic at.. > >>>> You are overdriving your sound card or the line out transformer in the > >>>> K3. > >>>> I have measured the third harmonic using an audio spectrum analyzer > >>>> at both the line out and headphone jacks of my K3. Until the level > >>>> becomes excessive (> .7V RMS on the Line Out) the third harmonic is > >>>> more than 50 dB down (Line Out) and more than 70 dB down (headphones). > >>>> 73, > >>>> ... Joe, W4TV > >>>> > >>>> _______________________________________________ > >>>> Elecraft mailing list > >>>> Post to: [hidden email] > >>>> You must be a subscriber to post to the list. > >>>> Subscriber Info (Addr. Change, sub, unsub etc.): > >>>> http://mailman.qth.net/mailman/listinfo/elecraft > >>>> Help: http://mailman.qth.net/subscribers.htm > >>>> Elecraft web page: http://www.elecraft.com > >>>> > >>> _______________________________________________ > >>> Elecraft mailing list > >>> Post to: [hidden email] > >>> You must be a subscriber to post to the list. > >>> Subscriber Info (Addr. Change, sub, unsub etc.): > >>> http://mailman.qth.net/mailman/listinfo/elecraft > >>> Help: http://mailman.qth.net/subscribers.htm > >>> Elecraft web page: http://www.elecraft.com > >>> > >> _______________________________________________ > >> Elecraft mailing list > >> Post to: [hidden email] > >> You must be a subscriber to post to the list. > >> Subscriber Info (Addr. Change, sub, unsub etc.): > >> http://mailman.qth.net/mailman/listinfo/elecraft > >> > >> Help: http://mailman.qth.net/subscribers.htm > >> Elecraft web page: http://www.elecraft.com > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Mike Harris-9
Alexandr Kobranov made an interesting post showing a spurious response
in the line out audio "I just made two basic samples using K3 and TS-850 using Firebox external soundcard and Winrad SW. You can see screenshot from K3 line-out audio on http://www.ok1kei.org/K3_audio/line_out_firebox_winrad.jpg This is K3 with 400Hz roofing filter on some stable carrier. LINE OUT setting on level 9. " Looking at the plot the spurious cannot be harmonics because the frequency scale of the ghost response is the same as that of the normal response. It is not doubled or tripled as would be the case with harmonics. I posted similar results in March which I noticed using PSK on a computer. Quoting myself: "The second thing I am noticing is ghosts in the waterfall display of MixW. I assumed that I was driving the audio card too hard and getting harmonics, but this is not the case. The ghost signals do move faster across the waterfall than the tuning rate implying harmonics but I can decode the ghosts, so the bandwidth of the ghost signals has not changed which it would do with a harmonic. Ghosts are about 20-30db down on the correct signals" It appears that this effect is nothing to do with clipping or transformer saturation but some kind of mixing. On the positive side I have not manged to make a ghost appear in the passband where it would damage the decoding efficiency, although it may still be there under the noise. This is an unusual effect that I have not seen before. Anybody any ideas of how these ghost signals are being generated? Andrew Forrest M1KAZ (K2 #3679,K3 #0499) -- _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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On Fri, 08 Aug 2008 09:30:55 +0100, Andrew Forrest wrote:
>It appears that this effect is nothing to do with clipping or >transformer saturation but some kind of mixing. I'm also not convinced that this particular screen shot is non- linear distortion. It could be aliasing in the FFT software that's part of the decoder. On the other hand, the pdf below DOES show both harmonic distortion and IM distortion on the Line Output when the Line Out level is set too high (driving the transformer being driven beyond it's ratings). http://audiosystemsgroup.com/K3FilterStudy.pdf 73, Jim Brown K9YC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I see the same extra stripe using mixw and an RF generator. I had to turn
down the line out of the K3 to 001 and crank up the sound card to max inorder to eliminate it. The level is a bit weak now and needs more gain. There is something not quiet right here. Steve Ellington [hidden email] ----- Original Message ----- From: "Jim Brown" <[hidden email]> To: <[hidden email]> Sent: Friday, August 08, 2008 1:19 PM Subject: Re: [Elecraft] Re: K3 Audio > On Fri, 08 Aug 2008 09:30:55 +0100, Andrew Forrest wrote: > >>It appears that this effect is nothing to do with clipping or >>transformer saturation but some kind of mixing. > > I'm also not convinced that this particular screen shot is non- > linear distortion. It could be aliasing in the FFT software that's > part of the decoder. > > On the other hand, the pdf below DOES show both harmonic distortion > and IM distortion on the Line Output when the Line Out level is set > too high (driving the transformer being driven beyond it's ratings). > > http://audiosystemsgroup.com/K3FilterStudy.pdf > > 73, > > Jim Brown K9YC > > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.138 / Virus Database: 270.6.0/1601 - Release Date: 8/8/2008 > 9:02 AM > > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hello,
last test to test possible AGC influence on ghost signals is here http://www.ok1kei.org/K3_audio/line_out_agc_off_500Hz.JPG K3 has AGC OFF and signals are shortly invoked on/off by RF GAIN knob. Line out is on 4, BW 400Hz (as roofing filter) Spectrum is wider to see 500Hz original and then signals around 1.5, 2.5 etc kHz. Without changing of soundcard input gain the same performed with TS-850 http://www.ok1kei.org/K3_audio/ts850_agc_off.JPG Also AGC OFF and af signal invoked by RF GAIN knob. There are no ghosts visible. (please ignore some permanent birdies on both pictures, look for signal on/off and ghosts on the right from original signals) So as AGC was completely OFF, signal generator was used and in both cases the same soundcard setting was used and the same SW, there is probably some source of K3´s ghost signals in DSP demodulator itself. Using so wide specrum (up to 5kHz) is only to illustrate how many and where all ghosts are... Hope somebody with less "amateur" approach can comment/explain. 73! Lexa, ok1dst K3/10 #727 K3 GhostBusters Club n4lq napsal(a): > I see the same extra stripe using mixw and an RF generator. I had to > turn down the line out of the K3 to 001 and crank up the sound card to > max inorder to eliminate it. The level is a bit weak now and needs more > gain. There is something not quiet right here. > Steve Ellington > [hidden email] > ----- Original Message ----- From: "Jim Brown" <[hidden email]> > To: <[hidden email]> > Sent: Friday, August 08, 2008 1:19 PM > Subject: Re: [Elecraft] Re: K3 Audio > > >> On Fri, 08 Aug 2008 09:30:55 +0100, Andrew Forrest wrote: >> >>> It appears that this effect is nothing to do with clipping or >>> transformer saturation but some kind of mixing. >> >> I'm also not convinced that this particular screen shot is non- >> linear distortion. It could be aliasing in the FFT software that's >> part of the decoder. >> >> On the other hand, the pdf below DOES show both harmonic distortion >> and IM distortion on the Line Output when the Line Out level is set >> too high (driving the transformer being driven beyond it's ratings). >> >> http://audiosystemsgroup.com/K3FilterStudy.pdf >> >> 73, >> >> Jim Brown K9YC >> >> >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> >> No virus found in this incoming message. >> Checked by AVG - http://www.avg.com >> Version: 8.0.138 / Virus Database: 270.6.0/1601 - Release Date: >> 8/8/2008 9:02 AM >> >> >> > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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On Fri, 08 Aug 2008 21:56:41 +0200, Alexandr Kobranov wrote:
>last test to test possible AGC influence on ghost signals is here When you turn off the AGC, you are likely to overload the audio system in any radio. The trace below is nothing more of less than harmonic distortion caused by the overload of an audio stage. Could be the K3, could be the sound card. http://www.ok1kei.org/K3_audio/line_out_agc_off_500Hz.JPG >Without changing of soundcard input gain the same performed with >TS-850 >http://www.ok1kei.org/K3_audio/ts850_agc_off.JPG The second trace shows that the audio system is not being overdriven. The difference could be nothing more than how levels are set or how much gain there is between the detector and the audio system. You've excited the audio system with a single frequency. If you excited it with broadband noise, as I did, you would also see the IM components of distortion. 73, Jim Brown K9YC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by N4LQ-2
I have noticed this effect in recent beta firmware revisions as well. I
spent quite some time looking at a busy band and chasing ghosts everywhere, trying to find out what was up. I searched the archives and saw others had the same problem; the harmonics do seem to be recent, as I've not been troubled by this effect before. Before I wrote I was waiting to see if someone did just this experiment you describe. One point: I have the HAGC mod on my desk still, though, so it's possible, especially after Lyle KK7P's last email about the HAGC mod, that my problem is related to the undone HAGC mod. However, if others with more recent K3s have the problem, then it isn't just that. Leigh/WA5ZNU K3#51 > I see the same extra stripe using mixw and an RF generator. I had to > turn down the line out of the K3 to 001 and crank up the sound card to > max inorder to eliminate it. The level is a bit weak now and needs > more gain. There is something not quiet right here. > Steve Ellington > [hidden email] > ----- Original Message ----- From: "Jim Brown" > <[hidden email]> > To: <[hidden email]> > Sent: Friday, August 08, 2008 1:19 PM > Subject: Re: [Elecraft] Re: K3 Audio > > >> On Fri, 08 Aug 2008 09:30:55 +0100, Andrew Forrest wrote: >> >>> It appears that this effect is nothing to do with clipping or >>> transformer saturation but some kind of mixing. >> >> I'm also not convinced that this particular screen shot is non- >> linear distortion. It could be aliasing in the FFT software that's >> part of the decoder. >> >> On the other hand, the pdf below DOES show both harmonic distortion >> and IM distortion on the Line Output when the Line Out level is set >> too high (driving the transformer being driven beyond it's ratings). >> >> http://audiosystemsgroup.com/K3FilterStudy.pdf >> >> 73, >> >> Jim Brown K9YC >> _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Jim Brown-10
I have seen the same odd order harmonics with my K3 with line out set way down (4/5) so that it is just high enough for the sound card to detect sensible signals - this was with AGC on though. The effect is present on the line out, speaker and phone jacks and I can actually hear the distortion through the cans in my Heil headset (in my good ear - no joke - I only hear the distortion in my left ear - my right ear has lost some hf response - proven by wearing the cans both ways round). My belief is that something is clipping somewhere either in hardware or software. Lyle is aware of the issue but not sure how high up on his priority list it is.
Regards, Paul. |
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In reply to this post by Joe Subich, W4TV-3
I have just observed this for myself. A fellow K3 owner who has been testing my KComm program persuaded me to try CW Skimmer. With the large very clear horizontal waterfall it is very easy to see duplicate signals occurring at harmonically related intervals. I have to reduce the LIN OUT setting to 002 for it to completely disappear. The mixer volume sliders have no effect on these harmonics. I don't have an oscilloscope so I can't be sure if the problem is occurring in the K3 or the input to the sound card. Skimmer seems happy at the low setting, but it is too low for my PSK31 software.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
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On Sat, 9 Aug 2008 15:27:08 -0700 (PDT), Julian, G4ILO wrote:
>With the large very clear horizontal waterfall it is very easy to see >duplicate signals occurring at harmonically related intervals. This is entirely consistent with my measurements. See the previously posted link. Jim K9YC _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Jim Brown-10
Jim, Just re-read this and got your point. This is interesting as I've observed identical issues. When monitoring a PSK31 signal using a narrow filter I could see a "ghost" signal on the waterfall which was at odd multiples of the base AF. I could also decode the ghost signal implying phase info was intact as was the bandwidth of the signal. This would imply some kind of harmonically related alias - not a simple harmonic. The sound card was way off clipping and line out was set low (can't remember exact setting but it was not greater than 4) and I've used this card (an Edirol FA66) with other radios for PSK using the same software without problems. Not sure if you read my other post but these effects are also audible in the cans (with my good ear!) Paul M1PAF |
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