Ok. I just never heard it before. I did recall others mentioning this. It is not loud. The amp works great.
J6/W0MU November 21 - December 1 2011 CQ WW DX CW W0MU-1 CC Cluster w0mu.net On 9/26/2011 1:07 PM, Eric Swartz - WA6HHQ, Elecraft wrote: > Hi Mike, > > This doesn't sound unusual. > > There is also a normal amount of 'resting' idle low level transformer > hum, which varies with line voltage and frequency. Also, when the > rear switch is on, the transformer primary is active even when the > front switch is off ( but the output windings are disconnected from > the amp.) the front switch is more like a stand-by - active switch. > > 73, Eric WA6HHQ > > --- > www.elecraft.com > > > On 9/26/2011 11:49 AM, Ron D'Eau Claire wrote: >> What you are describing is very unusual, Mike. >> >> Typically, one will hear some hum from the transformer with the "key >> down" >> (full 500 watt carrier). It is most pronounced when using the green >> transformer tap (lowest line voltage input). Normally there is no hum >> with >> the KPA500 off, or when running the KPA500 at low duty-cycle loads >> such as >> SSB, even at full peak power output. >> >> I'd drop a line to the elecraft support reflector and see what the >> Ele-guru's say. >> >> 73, >> >> Ron AC7AC >> >> -----Original Message----- >> >> My KPA500 now seems to have the hummms. It comes and goes whether the >> unit is on or off. It does go away when you turn off the rear switch. >> >> I noticed someone changed the tap and that appeared to fix the hum. >> >> I am running the amp on 110V. My actual wall voltage is 119V. >> >> I did not notice this at all while I was at our Montana home over the >> summer. >> >> Mike W0MU >> ______________________________________________________________ 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
