I'd suspect the diodes in the output SWR bridge, Bill. The K2 power control works by "requesting" the desired power by turning the POWER knob and then it ramps up the gain until the output SWR bridge reports the requested power.
With then inop the K2 ramps up full power trying to get a power level back that won't happen if they are dead. Don Wilhelm, W3FPR, is the resident K2 expert, having built and repaired countless K2s over the past dozen years or so. I suspect he'll jump in when he notes your message. But, if not, pulling one end of each diode loose and checking it for proper diode operation is likely to show one or both are no longer "diodes" ;-) 73 Ron AC7AC -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bill and Gail Stewart Sent: Sunday, March 24, 2013 4:09 PM To: [email protected] Subject: [Elecraft] K2/100 power problem I am trying to repair a K2/100 that I believe was damaged in shipment to me. The power output was erratic - sometimes almost no power out, sometimes about half power. I investigated the SWR circuitry in the KPA100 and replaced R29, which was discolored but still had the correct resistance. After carefully reassembling the unit, the power output is now greater than maximum rated power regardless of the power setting (just keyed momentarily and measured with a peak-reading wattmeter). The resistance from either side of R28 to ground is about 92 ohms, the same for the cathodes of D16 and D17. Is this correct? Is U5 blown? Thanks, Bill K5EMI ______________________________________________________________ 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
