[Elecraft] K3 QSK

[Merv Schweigert]

I posted that I could not duplicate the thumps on #2603.  After trying a 
few more times
I am hearing exactly what Mike describes, and after talking with Toby, 
it may be a
difference in terminology, at least on my part.  I hear the same thing 
but I describe it
as pops or clicks,  and as Mike says it seems to be from the high 
background noise,
not that I have a high level of background noise, mine is S2,  but from 
the high level
of the RF gain control,  I never hear these artifacts due to the way I 
use the AF/RF
controls,  my AF is usually set about 12 o'clock and RF about the same,  
I use the
RF as the gain control,  I think this was described many times in the 
past by others.
The thump is also noticeable if there are signals on the band inside the 
passband,  I have
the monitor volume set high enough that it equals those signals in 
volume so the
thump is less noticeable.
Some of these anomaly are hard to define,  and finding a word to 
describe the sound
is difficult.  To me its pops or dull clicks,  others its thumps, but we 
agree we are
hearing something.
73 Merv KH7C

> I can duplicate what might be called QSK thumps with high volume settings
> and using earphones or speakers. I have the choke change but have not
> modified low frequency response with larger caps. I think the thumps come on
> key up not key down.
> Everything is fine when I have the volume set at a normal level. I begin
> hearing thumps at a volume setting of 11 O'Clock.
>
> What I believe I am hearing though is not an artifact but just high band
> noise between dits that give an impression of thumps. The high band noise is
> being gated by TR switching. I suspect if I didn't live in a high noise
> environment I wouldn't here this.
>
> Mike Scott - AE6WA
> Tarzana, CA (DM04 / near LA)
> NAQCC 3535
> K3-100 #508 / KX1  #1311
>
> I sat down in TEST mode and tried all the combinations you mentioned again
> and can't produce thumps. I even tried every possible combination of AF/RF
> and MON levels with no thump. 
>
> So I'm sri to say obviously something is different between our rigs and
> setups, but I can't imagine what. 
>
> The only audio mod involving a change on the main board is to change a
> choke, not a cap. It reduces the resistance of the choke to improve the
> voltage regulation at the AF Amp. I've made that too. When I said my K3 was
> "stock" Elecraft, it does have the Elecraft-approved and documented mods
> made while writing the app notes. 
>
> I asked wondering if the capacitor changes some have made to improve the
> low-frequency response were making the low frequency 'thumps' stronger and
> audible. If you've not done them, we should have similar rigs. 
>
> Ron AC7AC
>
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