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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
