Chuck I agree with Joe's diagnosis. Try an experiment:-
Run 100w from the K3 alone and get a report. Then turn back the power so that K3 plus amplifier is producing 100w. See if the report is now OK, or muffled. If the report is OK, it could be RF feedback which only occurs at high power. If the report is muffled you might have an amplifier problem. John G4ZTR -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Joe Word Sent: 15 November 2011 18:52 To: elecraft@mailman.qth.net Subject: [Elecraft] KPA500 audio muffled? Chuck, I had muffled audio reports while using a Tokyo Hi Power 1.2Kfx amp. It has coming from RF getting into the amp. THP wrote it off, saying nothing they could (would) do about it because I was on the second floor. But... I now have a KPA-500 and have no problems on any band at any power level. Just a thought! Joe N9VX ---------------------------------------------------------------------------- ---------------------------------------- I have gotten a few reports of sounding like my audio is muffled as compared to running the K3 alone. It is true that with several listeners in different states, there is not a consensus of opinion on that. Some of the guys think it sounds just fine, and some say they can hear a slight muffled sound with the KPA turned on. The point of comparing it to K3 only and K3 with KPA500 is that the mic is not in the equation. The report is clearly that the amp sounds muffled. Not unreadable, just slightly muffled. I have a bias current of 0.4A...about the only thing I can think of to check. I think there was some discussion of setting the bias current here, but I can't find it again. What is the range of bias current for best linearity? I don't see any help in the manual. ----- Chuck, KE9UW -- ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __________ Information from ESET NOD32 Antivirus, version of virus signature database 6632 (20111115) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 6632 (20111115) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html