I've noticed that the first time I TX with my KPA500 it will fault. Seems to settle down after that. May also spoke after band change.
Sent from my iPhone ...nr4c. bill > On Mar 1, 2016, at 12:23 AM, Vic Rosenthal <[email protected]> wrote: > > 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, ______________________________________________________________ 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]
