[Elecraft] K3 Audio

[Julian, G4ILO]

Joe Subich, W4TV-3 wrote:
> 
>> 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).  
> 
> 

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
http://www.g4ilo.com/ G4ILO's Shack 
http://www.ham-directory.com/ Ham Directory 
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