Hi Working on my K2 with a long wire antenna and externalATU and my K2 shut down. Only working at 5 watts and an SWR of 2.1:1.
I didn’t smell anything initially so I powered it backup. At first I couldn’t hear anything on any band and slowly the sound cameback, which was a bit strange. The lights on the ATU no longer indicated any output sostarted checking a bit more when I got a faint smell of fried component. Before removing any covers I started checking basicthings. S meter stopped registering any received signals, although all bandscould be heard at normal levels. The ATU can only handle 15 watts so I tested up to thisand found that when I dialled in up to 10 watts, It was indicating 0.5 watts. Icould hear the KPA100 switch in at 11 watts but anything up to 15 watts showeda max of 6 watts. I bypassed the KPA100 by powering it from the base K2power socket and the I had the same results. I immediately thought that the finals have blown but whythe S meter issue? Here are some voltages as I worked through the transmittersignal tracing. P13 Basic voltagechecks step 4. Key down volts at D6 2.6v and D7 7.9v step 5. Power output 0.5W Page 14 Tx mixer,Buffer, Band Pass etc. Step2 Xmit Mixer Output 2.12vrms Step 3 Buffer Output 1.61vrms Step 4 BP filter output 5.65vrms Step5 T-R switch #1 output 5.6vrms Pre-driver, Driverand PA Step1 Pre-driver output 4vrms Step2 Driver Input 1.26rms Step3 Driver Output 8.2vrms Step 4 PA input Q7 1.77vrms Step5 PA input Q8 3.56vrms Step 6 RF detector input .38vrms Step 7 DMM set to Diode mode Q7 Base1.125 Collector1.12 Emitter0 Q8 B 1.12 C1.12 E 0 Something else I noticed was that when I turn the RF gaindown fully then back up to max, the sound comes back slowly and not at the samerate you turn the dial, there is a lag. These last results I think indicate the finals, but whereto start looking for the cause? Any help would be much appreciated. Mick ______________________________________________________________ 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 Message delivered to [email protected]
