Hi Ignacy. Many thanks for the response.
The reason for my query was that I was puzzled by my calculated efficiency numbers - I felt they were high. This also led me to wonder about the operating class of the amplifier, i.e. whether it was operating in linear mode on CW or not. I have confirmed the accuracy of the LP-100A which conforms broadly with the built in meter of the KPA500. The LP-100A was factory built so I'd get a NIST calibrated unit. It's an impressive instrument. I have not confirmed the accuracy of the KPA500 voltage and current measurements. I don't think there is anything to adjust in order to calibrate these. I did get a response from Wayne N6KR on another email list, where I posted my message as well. I'm sure he doesn't mind me quoting him: "As with all broadband power amplifiers, the efficiency of the KPA500 varies somewhat from band to band due to variations in matching circuit efficiency and transformer performance. That's why "typical" efficiency is specified." However, I got no comment on the operating class of the amplifier on CW or whether it depends on what mode you are operating the K3. Anyone? 73, Yngvi TF3Y http://www.tf3y.net On Tue, Jul 23, 2013 at 6:45 PM, Ignacy <[email protected]> wrote: > 78% efficiency seems high. But your calculations assume that all the meters > are accurate. > > KPA500 is rated at 500W in linear mode and is supposed to have an > efficiency > around 50% at this level. At a higher drive the amp will be less linear but > at a higher efficiency. At low power the efficiency increases linearly > with output power. If about 50% with 500W then about 62% with 620W. > > A data sheet for Microsemi 1 KW module shows efficiency curves in Fig 19 at > www.freescale.com/files/rf_if/doc/data_sheet/MRFE6VP61K25H.pdf. About 65% > > efficiency at 700W with IMD3<-40db. Reaching 80% at 1.4 KW and IMD3>-28db. > The dissipation is about 370W at 700W level and 350 at the 1.4 KW level. > These numbers do not include losses in transformers and filters. > > Ignacy, NO9E > > > > > > -- > View this message in context: > http://elecraft.365791.n2.nabble.com/KPA500-efficiency-tp7577015p7577042.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > 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
