Everyone, I have had my KPA500 linear for some time now and have been really happy with it. I use it with my K3 and they communicate with each other via the DB15 AUX cable that I built ( the one furnished by Elecraft was too short).
The only issue I have encountered is the finals in the linear seem to heat up rather quickly causing the fan to kick in in a rather short period of time. it doesn't matter if I use the dummy load or a good match antenna. I also noticed the finals seem to cool rather quickly after the transmittion is terminated and the fan turns on after about 30 seconds to one minute after starting a ssb transmittion then goes to a higher speed after about 30 seconds more. If my transmittion time is greater then 2 to 3 minutes the fans go to high and the final temperature is around 70 degrees C. I have never had the linear go in to a fault because of heat. The fix. I removed the top, front, and right side panels of the KPA500. When I first built the linear I realized the mounting screws that mount the Z panel to the amplifier module were too long so I used the shorter ones that would normally go to mount the top panel. On inspecting these screws they were tight. Looking at the right panel I noticed there are 4 screws that mount the panel directly to the amplifier's heat sink. They were not as tight as I would have liked. I wanted to get the most efficient heat transfer from the module so I carefully applied some heat sink compound to the side of the heat sink of the amplifier module before carefully mounting the right sied panel back on the amplifier. I carefully made sure the 4 screws that mount from the panel to the heatsink ( which are normally covered by the handle) were solidly and carefully tightened. After inspecting the transformer connections and the rest of the inside of the linear I reassembled it and tested it out. Findings. Now when I am running ssb typically the fan doesn't come on until well in to the qso and never has the fan reach high mode. If I brick the key at 500 watts into a dummy load the fan goes high after about 2 minutes. I also noted the finals heat up slower and cool slower and the left panel temperature follows the final temperature.. Now the amp seems very happy and I am not bugged by the constant fan noise during a qso. I thought I would pass this on to everyone. Thanks and 73 Dave KD1NA ______________________________________________________________ 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
