Yes. It has been mentioned on this list that the KPA500 is designed to be most efficient at 500 Watts and running at lower power does not mean saving the amp.
Sent from my iPhone ...nr4c. bill > On Aug 29, 2019, at 3:11 PM, Bob McGraw K4TAX <[email protected]> wrote: > > My KPA500 runs from a low of 35% to a high of 55% depending on power. Lower > power is least efficient. Thus I always run close or at maximum rated > power. Also the load impedance will affect efficiency. > > 73 > > Bob, K4TAX > >> On 8/29/2019 2:04 PM, John Simmons wrote: >> No one has mentioned amplifier efficiency at differing power levels. >> >> -John NI0K >> >> Andy Durbin wrote: >>> "They bias the LDMOS devices at 1 amp each. That is minimal in overall heat >>> when you are pulling over 40 amps at high power." >>> >>> You beat me to it. My KPA500, keyed but with no RF input, showed 0.5 A at >>> 76.7 V. That's only 38 W which is a small part of the 400 W plus PA >>> dissipation seen in some operating conditions. >>> >>> All my measurements of PA dissipation take PA DC input and subtract RF >>> output so my data include dissipation in the LPF. It would be interesting >>> to separate the dissipation in the finals from the dissipation in the LPF >>> but I don't know how to do that without modifying the amplifier. >>> >>> 73, >>> Andy, k3wyc >>> ______________________________________________________________ >>> 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] ______________________________________________________________ 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]
