My KPA500 hums in standby when PWM controlled heating elements on other circuits are operating. (coffee maker and flat iron, neither of which are mine) I assume it is a power quality problem, but I have no way to be certain.
--ae0mm -------- Original Message -------- On January 25, 2018 8:46 PM, Dave AD6A <d...@ad6a.com> wrote: > My KPA500 (that I built about a year ago) buzzes in the same way as > Michael's. > My transformer is hard against the rubber buffers, the double-rubber pads > are properly in place, and the bolt is nicely torqued down. I'd be > interested in hearing any ideas to mitigate this issue also. > > 73, Dave AD6A > > -----Original Message----- > From: elecraft-boun...@mailman.qth.net > [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Michael Blake > Sent: Thursday, January 25, 2018 5:50 PM > To: Elecraft Mailing List elecraft@mailman.qth.net > Subject: [Elecraft] KPA500 cabinet buzz > > I just built my KPA500 today and on the air reports were good. 20watts Drive > seemed right for about 500 watt peaks. After running it for about an hour I > shut down to clean up the kit building mess and when I returned later I was > hearing a loud 60 cycle mechanical buzz from the left side of the cabinet > when in operation. The buzz would vary from very light when keyed with no > drive to quite loud when putting out 500 watts CW. I had not noticed any > noise earlier but I was wearing Bose noise cancelling headphones as I > normally do. > > The voltage looks normal under load and the output power is 500 watts with a > little over 20 watts drive. > > I removed the top cover, loosened the transformer mounting bolt a bit, > turned it up on its left side to make sure the transformer was resting > against the two bumpers and retightened the mounting screw per the > instructions. This did not result in any change in the mechanical > vibration. > > Any suggestions? > > Michael Blake > k9...@mac.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 Message > delivered to d...@ad6a.com > > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus > > --------------------------------------------------------------- > > 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 > Message delivered to ae...@protonmail.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 Message delivered to arch...@mail-archive.com
