In some 120VAC installations with significant voltage droop under load, it's a challenge to find the right tap so the 60V output of the KPA500's high voltage supply doesn't sink too low "key down" or rise too high "key up". The 60V supply is not regulated.
If the voltage rises too much the amp will shut itself down to prevent damage. If the key down voltage drops below 60V IMD increases and the maximum power available may be less than 500 watts. The answer is to use the highest voltage tap that that keeps the idling voltage at 85V or less and set the maximum KPA500 output power where the voltage stays above 60V under load. That setting will vary from band to band according to the inherent efficiency of the amp. Also, keeping the SWR low will allow more power by keeping the efficiency of the amp as high as possible. Many, perhaps most, people outside of North America don't have that problem. They have 220V at all wall outlets. Someday we'll catch up :-) It reminds me of the angst over the switch from 6V to 12V automotive systems. 73, Ron AC7AC ______________________________________________________________ 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
