My test data show that, of all the bands my KPA500 will work on, 20 m has the lowest PA efficiency. My test data also show that the KPA500 efficiency, and therefore PA dissipation, is very sensitive to load matching.
So, if you are on 20 m and with a poor match, your 60 V PSU will have a high current demand and may sag below 60 V. A spot check shows my line input voltage is 123.4 V and my "60V" supply is 81.7 V while receiving. Line voltage is lower when the neighborhood transformer is loaded by heating or cooling systems. A TX at 14.074 into a dummy load gave 505 W out with PA 61.8 V and 14.3 A giving a PA dissipation of 378 W and an efficiency of 57%. It took 35.6 W drive to achieve this output. A TX a few minutes later with same drive power setting gave 527 W out, PA Diss of 369 W, and PA efficiency 58 %. LP-100A shows drive power still 35.6 W. One of the problems with making measurements like this is that you have to decide which data to believe. The controller that gives my real time KPA500 data is using KPA500 reported current , voltage, and output power. I think my LPA-100A is more accurate for power measurements but its data are recorded by a different logger. I'm not motivated to merge the two data sets right now. Andy, k3wyc ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
