Thanks for the info Don. I just ordered the PA kit from Aptos...
73 de John K2ZA Sent from my iPad On Aug 10, 2013, at 0:04, Don Wilhelm <[email protected]> wrote: > John, > > What is the DC voltage at the base of Q7/Q8 during a TUNE? If it is in > excess of 0.64 volts, then Q11 and Q13 as well as Q7 and Q8 are toast. Order > and install the K2PAKIT which includes all those parts. Q7 and Q8 are > connected in push-pull output, so a failure of one will reflect on the other. > > I don't know how that would change the behavior of the KIO2, so you may have > multiple problems in your K2. > > If you want to do a test, remove the KAT2 and try working into a 50 ohm dummy > load. If you then have good power output, the PA transistors are OK and the > problem lies with the KAT2, > > 73, > Don W3FPR > > On 8/9/2013 11:39 PM, John Zaruba Jr wrote: >> I was using my new to me K2/10 (S/N 50xx) which has been working flawlessly >> for the last 2 months when out of the blue I started getting a P LO message >> from the KAT2. I checked the power out with an external meter and it was >> about .4 watts in general agreement with the K2 power display. No snap, >> crackle, or other dramatics, just loss of power. Coincident with the output >> power failure, the KIO2 stopped working, neither receiving or sending data. >> Coincidence does not imply causality, so I'm going to treat this as a >> separate issue. >> >> I started signal tracing per the manual with a DSO scope (Tek TDS-210) and >> the RMS voltages I read on the scope were nothing like the voltage charts, >> so I was just looking at voltage gains from the various stages. I removed >> the KSB2 and installed the cap and 2 jumpers to eliminate that module, with >> no symptom change. >> >> The one anomaly I think I've found occurred with Q7 & Q8, the voltage at >> each device's base lead was 3.2 VRMS (as measured by the cyclic RMS setting >> on the scope), but the collector voltages were around 500 mVRMS. Just to >> clarify my thinking, I would expect the collector voltage to be >> significantly higher than the base voltage. >> >> As an additional question, if I have had a final amplifier failure, what >> might cause both devices to fail, rather than one or the other? Hopefully I >> can receive some wisdom from the list before I call the factory on Monday to >> order parts (to make sure I get the correct ones) I'm also thinking I should >> order new thermal pads and shoulder washers, if new finals are indeed >> required. > ______________________________________________________________ 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
