Hi: I, too, am experiencing this exact problem, so, please add me to the list for a solution.
My KPA500 operates wonderfully most of the time, but every once in while (perhaps one-in-ten Power-Ons), it has no "Operate" PA power even though the exciter asterick is normal and the "Standby" is normal. Parameters are as follows: KPA500, Serial 792 Exciter: Flex-3000 PWR Output: 50-Ohm Dummy Load or antenna (has no effect on PA function problem). PTT: manual switch (normal PWR asterick indicates exciter power regardless of whether PA is functioning or not). SWR LEDs Function normally except when no PA: no lights. Mode: SSB or AM HV= 74 in Standby, HV= 64 fwhen functioning normally with 100W carrier (I have not tested HV during the symptom yet, but will do so). PWR= 100W carrier (when functioning normally) Current= 5.5 (when functioning normally with 100W carrier) I hope this helps troubleshooting. 73 Hal KK6HY [Elecraft] [KPA500] Peculiar behavior : no power output on Operate To:elecraft@mailman.qth.net Hi, this is IW0HQE, Alessandro, from Italy, a very happy owner of the superb K-line. I would like to report what I consider a minor issue/behavior of my KPA500 power amplifier. The amplifier is working flawlessly, and I am definately very satisfied with it. Only a very peculiar event happened a couple of times during the last week : when I turned on the amplifier and put it on Oper mode, when I begun my transmission the PTT triggered correctly (the * symbol appeared as well in the leftmost part of the display) but there was no power output at all. This was solved by simpli turning the amp OFF and then back online. I will now describe the event with further details : 1) I have owned the amplifier since 18/09/2012 (one month) and the event happened only two times during the last week. 2) The first time the event happened was right after my last K3 and P3 firmware upgrades. After upgrading both the devices, I then turned on the KPA500 to work a DX station and there was no power output; turning OFF and then back ON the amp solved it. 3) The second time the event happened was a couple of days later : I was listening to some DX stations and pileups for fun, then I needed the amplifier to make a few calls, I turned ON the rear panel switch, put the amp on OPER and then begun transmitting, but still no power output. Turning the amp OFF and then ON solved it. 4) Both times the event happened, the rear panel switch was turned ON from the OFF position. 5) Power drive 20 watts. CW mode. 6) Temperature reading at the moment of the event : 22-23 ?C. 7) SWR of my antenna on the band (15 meters the first time and 10 meters the second time) 1,3:1 or better. 8) HV : 74,3 9) Both the events happened after installation of Firmware Revision 04.51 and DSP 2.76. 10) I tried to turn off the amplifier after the second event without switching the real panel button in the OFF position, and the event never happened again. I cannot figure out if this is just a coincidence, but maybe it could be of some use to report it. I have seen this event, or some that have a strong resemblance have already been reported : http://elecraft.365791.n2.nabble.com/KPA-500-no-RF-until-power-cycle-td7017734.html http://elecraft.365791.n2.nabble.com/KPA500-No-power-out-in-quot-OPER-quot-mode-td7472228.html I have reported mine also, as suggested by W6FB, Jack Brindle, so that Elecraft could add this to the feedbacks already received, evaluate and (I hope) find out and solve this minor issue. Thank you for your attention. My very best regards. IW0HQE - Alessandro Merolli ______________________________________________________________ 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