Brent, If I were you, I would order 2 1N5711 diodes (PN E560004).
I suspect that your original problem is that KPA100 diodes D16 and D17 were damaged by static, with the result that the KPA100 output was at maximum (150 t0 180 watts) no matter what the power setting. That condition continued for long enough will place stress on the base K2 PA transistors and they will die of overload. I just recently responded to a similar private enquiry, I copy my response below.. Replace Q11 and Q13 since they also can be damaged as a secondary effect. --------------------------------------------------------------------------------- If you did not try to transmit for long after you saw the HiCur display, the base K2 PA transistors may still be OK. Your main problem is that the KPA100 wattmeter diodes have either shorted or opened, so the K2 can no longer determine power output. Since the K2 MCU thinks there is zero power output, it increases drive to the maximum - an external wattmeter will normally show 150 to 180 watts. That does place stress on the base K2 PA transistors which may fail as a secondary effect. If that describes your situation, replacement of KPA100 D16 and D17 may normally set things in order again. To prevent similar further incidents make certain there is a good DC path across the feedline of all your antennas. "Other transceivers do not have this problem" will fall on deaf ears here. The "other transceivers" control power output only by changing the drive to the final stages. Elecraft products actually measure the power at the output stage and control the power output by a closed control loop. That does require sensitive diodes at the output of the PA, but it also means that those diodes are susceptible to static charges on the antenna. Static on the antenna can be caused by wind, rain, sleet, snow or nearby lightning charges. A 2 or 3 watt resistor with a value between 5000 ohms and 100k ohms across each feedline will be a great help in reducing the number of failures of KPA100 wattmeter diodes. -------------------------------------------------------------------------------------------------- 73, Don W3FPR On 8/23/2012 7:47 PM, Brent Sutphin wrote: > We had a storms in the area here yesterday. Afterwards my K2-100 would not > stay on. When I turned it on, it came on for a few seconds then a high > current warning and then off. Long story short I determined that the K2 rf > power transistors are bad. I plan to order new ones tomorrow. Question is, > do I need to look further? > > Brent WB4X > > ______________________________________________________________ > 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 > ______________________________________________________________ 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
