I have searched the archives in vain for an answer (might just be my limited knowledge, however). My K2, which had been operating properly as a basic 10W, CW only with only the 160/RX antenna option installed, suddenly began having virtually no output on transmit. When I opened it up, I found that Q11 was completely split in half.
After checking everything I could, I replaced Q11 and Q12 (this was a long, involved process). I checked Q7 & Q8 for shorts to ground and found them to be OK. I applied power but did not turn on the radio. OK so far. When I turned on the K2, Q11 immediately began to smoke and burst into flames within a half second. I turned it off as quickly as I could. When I checked Q11 and Q12 for short to ground I found that all leads of both transistors were shorted to ground. I removed the devices and checked the pads in the same way. Now only the emitter of Q11 showed short to ground, which is correct. I checked Q6, Q7 and Q8 for shorts to ground. Emitters of Q7 and Q8 show short to ground which is correct. Q6 showed 1.5 ohms, which is also correct. I also found that the resistance to ground from the emitter of Q13 to ground showed 756 ohms, even when I disconnected R63 from the junction of R60 and R62. I expected to see about 2.8K ohms. From what I can find on the schematic, there should be no other path to ground, but I'm not sure about this. I don't know if I should be looking for a short or looking elsewhere. Can anyone advise if this last measurement is correct? Where should I look for the overall problem if this last resistance is not the problem. Thanks and 73 Alan K6ZY ______________________________________________________________ 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
