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: Elecraft@mailman.qth.net > >>>> 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: Elecraft@mailman.qth.net > >>> You must be a subscriber to post to the list. > >>> Subscriber Info (Addr. 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