Not to worry, my K3S does it too :-( On Mar 1, 2016, at 8:12 AM, Bill Hammond via Elecraft <elecraft@mailman.qth.net> wrote:
> Hi John, > My power dances all over the place (my serial number is 00069). Just had a > quick QSO with the KPA500 indicating 560 watts at the beginning and then > going down to 480 at the end. That is typical. My 12 volt supply drops to > 12.2 on transmit, 13.3 on receive. I have a long 12 volt cable from the > supply so “I" squared losses are understandable in the cable. Driving power > from the K3 is variable per band but typically set to 25 watts or so. The > QSO described above was on 17 Meters and the drive is 25 watts there for ~500 > watts out or just below after stabilization. > > I remember the power fluctuation issue being discussed years ago on this > reflector and it was explained that the power control uses a sampling and > feedback loop that takes “time” to stabilize. That said, I believe we are > both experiencing some power fluctuation over 10% in a short period of time. > Depending on the amplifiers we are using this could cause real downstream > issues, like distorted signals, spurs or alarm faulting of smart amplifiers. > > Could we have some aging component that is aggravating this issue? Our K3’s > are among the oldest on the air. > > 73, > Bill-AK5X > > > >> On Feb 29, 2016, at 2:24 PM, John K1JD <johnk...@comcast.net> 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: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 wham...@aol.com > > ______________________________________________________________ > 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 w...@triconet.org ______________________________________________________________ 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
