I have recently assembled KPA500 serial number 641. When testing into a dummy load I find that I get a large variation in the DC power input when driving for 500W CW when I go from band to band. My worst band is 21MHz, where I get the highest current (lowest efficiency). The drive was adjusted to give 500W as indicated by the LCD display. Here are my results:- 1.8MHz DC current 10.0A fan hardly ever comes on 3.5MHz DC current 10.0A fan hardly ever comes on 7MHz 12.0A 10.1MHz 12.4A 14MHz 14.3A 18.1MHz 13.8A 21MHz 16.4A temperature rises rapidly and fan soon gets to full speed 24.9MHz 13.5A 29.7MHz 12.3A I have no results for 50MHz band as I have no transceiver covering that band. The readings drift as the heatsink (and the dummy load) warm up, and so I took readings quickly and allowed time for the heatsink to cool down between each band. I find that the KPA500 current sensor tends to give low readings. I would be interested in knowing how other amplifiers perform. David Park G3PSV ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net
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