Les, Your implication that an active device failure is a rare occurrence is correct. Is your Q6 a 2N5739 or a 2N2166? If it is a 2N5739, change R46 from the 270 ohms value to 330 ohms to reduce the base current and also the heating of Q6.
73, Don W3FPR On 10/5/2010 8:46 PM, Les Rabe wrote: > I've spent the last 4 weeks or so with a problem I noticed in > Alignment and test Part III on page 78 of the manual. I've been > monitoring some of the posts here which have been very helpful in > keeping me on the right track with the debugging. My own K2 would only > produce 1/2 watt of output when I tuned L1 and L2. > > I finally realized that the current was stopping right at Q6, and after > having spent the last 4 weeks trying to find bad solder joints and > poorly tinned toroid leads I grabbed some courage and pulled Q6 out of > the circuit and tested it. It was shorted. > > My question is this: What should I test to assure myself that I won't > just burn out the new part? It is perhaps possible that Q6 was bad all > along or damaged during construction, but it is also possible that > something in the circuit caused the failure. R50 was also bad. There > were no sparks, smoke or burning smell anywhere when the rig was turned > on and I haven't found any damage to suggest a major electrical event. > > Thanks. > > Les > AB9WN > ______________________________________________________________ > 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
