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. ----- 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 -- View this message in context: http://n2.nabble.com/K3-Harmonic-Distortion-tp797780p833328.html Sent from the Elecraft mailing list archive at Nabble.com. _______________________________________________ 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
