Hi john, I think I've seen this myself. I would redo the power calibration with the K3 utility and a good dummy load. I'm interested in hearing people's responses to your question.
Vic 4X6GP > On 29 Feb 2016, at 10:24 PM, John K1JD <[email protected]> wrote: > > Hi All, > My K3 SN #071 was purchased new November 2007. It’s had a few mods/upgrades > along the way and its firmware is current. > > Last Field Day 2015 at W5YA, the K3’s LPA failed after a close lightning > strike. I was able to successfully repair the LPA replacing both discrete and > SMD components. Performed a Pout calibration using the K3 Utility program > afterward and it passed. > > My 9500 amplifier (driven by the K3) has had a few instances of a high plate > current faults since new in December 2010. These faults had been infrequent > enough to ignore. More recently though the problems have been occurring more > often. Swapping the tube did not help nor did careful inspection inside the > amplifier reveal anything. > > Evidence that the problem is related to the K3 and not the amplifier > presented itself by accident a few days ago. I had the K3’s output set to 40w > and the Alpha was off. I inadvertently bumped the key and noted an > instantaneous output of 54w on the Powermaster II wattmeter. A few more dits, > and the power output settled back to 40w. Hmmm… if the amplifier had been in > line, the K3’s drive set for full legal limit and a first dit resulted in an > additional 30% drive, a high plate current fault might certainly happen. > > This morning I was using the KPA500 amp with my K3’s power set to 28 watts. > After an early AM CW fix I left the station on, walked away and came back in > a few hours hours. On first dit the KPA’s instantaneous power showed 650w on > the Powermaster II and illuminated a red LED on the KPA500, then settled back > down to <500w. > > OK, so it IS the K3 causing the problem BUT the power output spikes occur > very infrequently. It’s difficult to nail down the cause or even the > conditions under which the problem is most likely to occur. > > Reading the archives, others have had power spike issues over the years. Is > there a known fix? I’ve looked briefly at Elecraft’s alerts and mods but > nothing jumps out. > > 73, > John K1JD > Santa Fe, NM > > > > > ______________________________________________________________ > 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 > Message delivered to [email protected] ______________________________________________________________ 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 Message delivered to [email protected]
