Yes, I was wondering why this was so interesting. Chuck Jack Hawley KE9UW
Sent from my iPhone, cjack > On Feb 10, 2020, at 12:47 PM, Bob McGraw K4TAX <[email protected]> wrote: > > Unless one is concerned about power consumption, the efficiency factor should > be really of no concern. Total heat output will always be greater at > maximum output and less at lower power. Nice for warming the shack on a > Winter day. > > > Bob, K4TAX > > > Sent from my iPhone > >> On Feb 10, 2020, at 12:18 PM, Andy Durbin <[email protected]> wrote: >> >> >> "This is probably what folks are thinking of when they assume maximum >> dissipation occurs at less than full output." >> >> A possible source of error in my data is that the dummy load is cool at the >> start of the power ramp and hot by the time peak power is reached. I >> recorded LP-100A data during each test run and can see some change in the >> load characteristics. I did not attempt to compensate for this when >> plotting the data. I simply reported values of R and X that were about >> average for each test run. >> >> One way to find out if the change in load is significant would be to start >> the power ramp at maximum power rather than minimum power. >> >> Some time after I ran those tests I expanded the capability of my Arduino >> station controller to add a page that displays PA voltage, PA current, PA >> DC input, PA dissipation, RF Output, and efficiency. A snapshot of the >> displayed data can be sent to the controller's logger output. >> >> I just ran a test which had a brief transmission close to full power and >> another brief transmission at half power. This test was performed at 14.01 >> MHz using a dummy load. Here are the data: >> >> 26:36:36.672 KPA Mon frozen >> PA voltage=60.6 >> PA current=14.1 >> PA input=854 >> RF out=495 >> PA diss=359 >> PA effic=57 >> >> 26:37:32.437 KPA Mon frozen >> PA voltage=64.6 >> PA current=10.0 >> PA input=646 >> RF out=250 >> PA diss=396 >> PA effic=38 >> >> Dummy load heating would not have been significant factor in this test but >> the results still show higher PA dissipation at 250 W out than at 495 W out. >> >> It's really simple to produce a similar data set and there are lots of >> KPA500 owners here. If you think my data are invalid please share your >> test data. I don't mind being wrong as long as I learn something new. >> >> 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]
