Folks, I thought I would pose this problem to the group. We were using my K2-100 at FD this past weekend when at 2 am it railed the 25 amp switching supply and showed 1 watt out at 9.9 to 1 swr on the LCD meter. In addition, the high current display would come on as well. Also, the bar graph indicated no output in either the keying mode or tune mode.
Upon getting the rig home, I separated the 100 watt module from the main rig and powered it up on the 5 amp supply plug on the rig. The radio worked fine with fully adjustable power out all the way up to about 15 watts and the bar graph was fully functional. But, using the 100 watt module as the power source and connected normally, the power out will jump to a full 100 plus watts at any power setting over the relay pull in at about 11 watts indicating no power out ALC loop voltage coming from the 100 watt module to control the rf output in a linear fashion. If you hit and hold the tune button it will go to full output immediately and not fold back to 20 watts. Looking at the schematic it seems there is a problem in the SWR Bridge circuit in the 100 watt module. I can see good rectified voltage at the output of D16 and 17 but after that I do not know what voltage levels I would expect to see at the outputs of the op amps in U5 (pins 1 & 7) or at the VRFDET pin 6 of U6. Something has bit the dust between the SWR bridge and the VRFDET output causing the power output regulation loop to open up. Has anyone else seen this particular problem ? What variable voltage levels should I see at the input pins of U5 and U6 ? Thanks in advance, Joe K8FC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
