I was gifted a KPA-500 in Aug. 2019. Used about a month before It blew a main line fuse. That was replaced and the amp remained dead. What happened was the center bolt holding the power transformer was not torqued down properly and when the amp was tilted the core shifted into the low voltage supply and damaged it requiring replacement at the Elecraft shop. Hopefully, that is not what knocked out your 12 volt supply? 73, Mike AC5P On Monday, January 17, 2022, 12:52:13 PM CST, Jack Brindle via Elecraft <[email protected]> wrote: I would not go by this. Many, if not most, KPA500s do not have noticeable hum when powered. Neither of mine do except for once in a while when the line voltage increases for a short time.
If yours does have noticeable him, you may want to check the tightness of mounting nut for the power transformer and retighten if needed (assuming it bothers you). There is a spec for the tightness of that nut. I believe it can be found in the assembly manual, if not also in the operating manual. 73, Jack, W6FB > On Jan 17, 2022, at 3:08 AM, Dave <[email protected]> wrote: > > When the rear power switch is turned on, you should hear a hum from the > transformer. The noise level from my KPA500 is quite audible from 2 or 3 > feet away with everthing else turned off. If you don't hear the hum, it's > likely there isn't power reaching the transformer. > > 73 Dave G4AON > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
