I may be wrong, but that may not be what Dick, WM6G, is referring to. I've had a KPA500 for quite some time, so I have an idea of what constitutes "normal."
In the last few months I've noticed that every morning, between roughly 9-10 AM, I hear brief 1-5 second pulsations of easily audible hum emanating from the KPA500. The pulsing events last perhaps 30 seconds to a minute, and may happen more than once. Yes, this ceases if the power cord is out or the power switch on the rear is OFF. But again, it is brief-lived when it occurs, and it's new. To me, guessing, it sounds like something connected to the main AC feed is coming up out of phase, then finally syncing, after which the hum stops. A neighbor's solar array? I have no idea as of this point. 73 Chris NW6V >Message: 23 >Date: Wed, 27 Jun 2018 12:48:19 -0500 >From: Bob McGraw K4TAX <rmcg...@blomand.net> >To: elecraft@mailman.qth.net >Subject: Re: [Elecraft] KPA500 Noise While Off >Message-ID: <47eb73a6-cc2f-5fd6-4318-17e76867d...@blomand.net> >Content-Type: text/plain; charset=utf-8; format=flowed > >Although the front panel switch is OFF, the control circuit of the power >supply remains ON as long as the rear power switch is ON or power is >applied.? It is normal to hear a small amount of hum from the power >transformer and the left rear of the cabinet to be slightly warm.? See >page 14 of the KPA500 manual for more detail.> > >73 >Bob, K4TAX ______________________________________________________________ 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
