[Elecraft] K3 Harmonic Distortion

[Julian, G4ILO]

The spectrum display you sent me shows an excessive level of 
50 Hz harmonics - some 15 dB above the noise floor and only 
40 dB below the desired signal from 150 Hz to above 3 KHz.  
That strongly indicates serious grounding issues, power supply 
filtering problems, improper power supply decoupling and/or 
soundcard instability.  I suggest you read K9YC's information 
on interfacing and RFI www.audiosystemsgroup.com/publish.htm 
and resolve that noise issue first.  I have seen the K3 audio 
output "go spurious" when presented a bad load or encountering 
regeneration (feedback from powered speakers) due to bad grounds.  


There is another possible cause of this. The VFO could be being modulated by
the magnetic field from an adjoining power supply transformer. I had this
happen to me (not with the K3) and the result was a "rough" sounding note.
It's easy to check for - just move the radio as far away from the PSU as it
will go.

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Julian, G4ILO. K2 #392  K3 #222.
http://www.g4ilo.com/ G4ILO's Shack   http://www.ham-directory.com/ Ham
Directory    http://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 
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