Brian, thanks for that tip. I bought this K3 used, so I didn't put it together. Will have to inspect to find out if pads are installed. The serial # 2241 suggests to me that the pads might indeed be missing.
Recalibrating the wattmeter plus TX gain did not eliminate the problem of the K3 powering down, and there is still a gap in obtainable output powers. After recalibration (without the KPA500) the powers not obtainable on 80m was anything between 12 and 16. I get the impression that this is normal behavior. Not a problem for normal hamming, and only a minor annoyance when using the rig as a variable power test instrument. Running the same endurance test with power setting 12W on 20m did not seem to lead to the rig shutting down, and the range of unobtainable output powers is actually between 9 and 12. I attribute this to variations in wattmeter sensitivities between 80m and 20m. Of course the wattmeter calibration is performed only on the 20m band. As I performed the wattmeter calibration today I ran into a complication that I don't remember from last time I did this (over a year ago). Following the manual instructions I set the power to 5.0W. (I did this using the power knob; first I misread it to mean tweak the power setting to obtain a 5W indication on the external wattmeter. The manual really should not be ambiguous on this). I brought up the CONFIG:WMTR LP display as instructed. I then held TUNE to start transmission, and was ready to adjust the main tuning knob to get 5W on the external meter. However, the transmission did not utilize the 5W PWR setting. Instead it used the TUN PWR setting, which happened to be very different. To complete the procedure I had to go back and adjust TUN PWR to 5W. I must be missing something here... 73, Erik K7TV -----Original Message----- From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> On Behalf Of Brian Hunt Sent: Wednesday, March 28, 2018 4:24 PM To: Elecraft@mailman.qth.net Subject: Re: [Elecraft] K3 powers off when after several minutes of 12W carrier For folks who run lots of high duty cycle modes, Elecraft is now recommending 'thermal pads' between the LPA transistors and the bottom cover. I found this out when I was doing some mods to my 10yo K3 and the instructions said to install them and I didn't have 'em. You can get them from Elecraft, not expensive. 73, Brian, K0DTJ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to ebasil...@cox.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
