It's not fan noise. It's definitely 60hz hum likely due to transformer for some reason. This was a factory assembled unit. I'll take the lid off and check it out the bolting. I'm currently running on a shared household circuit with who-knows-what connected elsewhere. The shack will get a dedicated 20A circuit soon.
Thanks all Jim On Tue, Jun 11, 2013 at 11:58 AM, Jack Brindle <[email protected]> wrote: > Jim; > > Make sure the transformer is bolted down appropriately. If it works loose > then it will cause the hum. > > Jack Brindle, W6FB > > > On Jun 11, 2013, at 7:51 AM, Jim Miller <[email protected]> wrote: > > > I leave my KPA500 back panel switch in the ON position most of the time > and > > use the front panel switch to bring it to life. > > > > However in even when in the "Front panel off/Back panel on" state the > > KPA500 will occasionally hum for a few seconds. > > > > Is this normal? Any suggested causes to worry about? > > > > Thanks > > > > jim ab3cv > > ______________________________________________________________ > > 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 > > > ______________________________________________________________ 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
