The fan rarely ever kicks in for me. My QSO's are pretty short. DX, contests. The only time I have really seen the fans go on is with RTTY. To it sounds like the OP has or had a problem with the initial build. If the screws were loose that secured the heat sink panel I could see that being problematic.
When in J6 we upped the fan speed on the outset to about 3 because it was always 80 degrees plus and very humid so I wanted to keep the air moving. We ran the CQ WW CW and never had one issue with heat or anything for that matter. Mike W0MU W0MU-1 CC Cluster w0mu.net:23 or w0mu-1.dnsdynamic.com Http://www.w0mu.com On 6/18/2012 11:51 AM, Guy Olinger K2AV wrote: > My question is whether you actually increased the no-fan heat dissipation > of the heat sink complex that significantly, or whether what you did is > faking out the heat sensor and causing the fan to NOT come on when it > actually should. > > It bothers me also that the increased dissipation is non-symetrical, and > will cause one side of the heat sink to be at a different temperature than > the other. This is a bad situation that theoretically can damage > transistors by putting unequal mechanical stress on the mounting in high > heat situations. It also could cause one transistor to be a lot hotter > than the other. Or it COULD be that what you did equalized heat > distribution. The problem is that YOU DON'T KNOW WHICH ONE. > > Fan speed, when it comes on, size of heat sink, etc and the transistors > used are a very carefully engineered COMBO. I really would not screw > around with it UNTIL you have discussed it with the Elecraft engineer and > have his concurrence. There is a lot more here than meets the eye. Be > very careful what you recommend to other owners. Elecraft please weigh in > before this gets around as an ill-advised urban myth, if indeed it is > ill-advised. > > Beyond that, why is everyone so aroused by fan speed? Fans keep things > cool. Fans are good. > > My roaring 100 CFM monster fan on my contest 3-1000Z amp, my > "Loudenboomer," keeps me from melting it when I qsy all over the band and > don't remember to retune it. I get pretty stupid late into a contest. > Roaring fan makes 3-1000Z last long time. 3-1000Z getting expensive and > hard to find. Roaring fan is my friend. Need to use headset anyway for > best diversity on 160. Use noise cancelling headset, can't hear the roar. > > Fans are your friend. > > 73, Guy. > > On Mon, Jun 18, 2012 at 7:42 AM, David Robertson<kd1na...@gmail.com> wrote: > >> 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 >> > ______________________________________________________________ > 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 ______________________________________________________________ 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
