KPA500 Hum
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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 -- J6/W0MU November 21 - December 1 2011 CQ WW DX CW W0MU-1 CC Cluster w0mu.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by Eric Swartz - WA6HHQ
Twice mine has hummed loudly enough (always when off from the front, on from the rear) that I looked for the noise, and unplugged it. I guess perhaps it's related to line voltage, which changes. I will monitor line voltage with my KILL-A-WATT meter and see if I can correlate it.
Leigh/WA5ZNU |
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In reply to this post by Eric Swartz - WA6HHQ
Ron D'Eau Claire wrote:
>Mike, I certainly concur with Eric's observation. What I thought was >very unusual was that you said that the hum would come and go, which I >presume happens when you aren't doing anything at the amp. > Hum that comes and goes for no apparent reason might be caused by some other large electrical appliance distorting the AC supply waveform - for example, an electric motor with a chopper-controlled Variable Speed Drive. Although the 60/50Hz hum level from the KPA500 transformer is normally very low, a sudden increase in the higher harmonics could be quite noticeable. -- 73 from Ian GM3SEK http://www.ifwtech.co.uk/g3sek ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Hope there comes a hardware mod to obtain minimum hum.
73 Arie PA3A ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Hello Arie,
There has been additional new hardwares in the installation of the transformer as in the latest KPA500 kit construction manual. I have solved the hum problem by trying another transformer tap and installing the new hardwares. TNX & 73, Johnny VR2XMC 從︰ Arie Kleingeld PA3A <[hidden email]> 收件人︰ [hidden email] 傳送日期︰ 2011年09月27日 (週二) 9:23 PM 主題︰ Re: [Elecraft] KPA500 Hum Hope there comes a hardware mod to obtain minimum hum. 73 Arie PA3A ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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