I really do NOT understand why this data is so surprising. It all seems to me to be perfectly normal with the amplifier's highest efficiency occurring at near max output. Which curiously, I would assume, is the way the amp was designed.
Think zero output with zero drive = zero efficiency. Apply some drive, read some output and the efficiency goes up from there. 73, Charlie k3ICH -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of j...@kk9a.com Sent: Friday, August 17, 2018 8:57 AM To: elecraft@mailman.qth.net Cc: char...@k5ua.com Subject: [Elecraft] KPA-1500 Efficiency As A Function of Input Power Interesting data, Charles. I assumed that running the KPA1500 (or KPA500) at lower power would keep the fan from running as much. I knew that efficiency changed with output power but I did not expect that it was this significant. If your data is correct there is 1000++ watts of heat to dissipate no matter what power level you use. John KK9A From: charles k5ua Date: Fri Aug 17 01:17:49 EDT 2018 Upon further testing, I have found that the efficiency of the KPA-1500 is varies greatly with driving power. The following table illustrates the relationships between exciter power, voltage, current, power-in(voltage x amps), power-out, efficiency, and dissipated power. The following test was made with the KPA-1500 into a dummy load and readings from the KPA-1500 utility software. (Exciter)(Amps) (Voltage) (Power-In) (Power-Out) (Efficiency Pout/Pin) (Dissipated Pwr) 10w 29a 52.7v 1528w 375W 375/1528 = 24.5% 1205w 15w 37a 52.7v 1950w 620w 620/1950 = 31.7% 1335w 20w 43a 52.6v 2262w 861w 861/2262 = 38.0% 1413w 25w 47a 52.6v 2472w 1060w 1060/2472 = 42.8% 1451w 30w 51a 52.6v 2682w 1227w 1227/2682 = 45.7% 1420w 35w 53a 52.5v 2782w 1380w 1380/2782 = 49.5% 1412w 40w 55a 52.5v 2887w 1497w 1497/2887 = 51.9% 1382w 45w 56a 52.5v 2940w 1600w 1600/2940 = 54.4% 1313w 50w 57a 52.5v 2992w 1703w 1703/2992 = 56.9% 1315w 53w 59a 52.5v 3097w 1825w 1825/3097 = 58.9% 1306w The remarkable thing is that DISSIPATED POWER appears to be relatively constant from 375w output through 1825w output. This implies the KPA-1500 will need to dissipate nearly the same amount of heat at low power output as at high power output, if I am interpreting the data correctly. I would like to know from Elecraft if this is normal behavior. Charles K5UA ______________________________________________________________ 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 pin...@erols.com ______________________________________________________________ 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
