Hello - Two nights ago I completed the assembly of my K2's RF board, and after a visual inspection verification of resistance checks, I assembled the radio per the instructions and began the third phase of alignment and test. I've discovered a problem right off the bat, though. In the 40 meter transmitter alignment section, when I put the K2 into tune mode at 2 watts power, I'm only reading .3-.4 watts on the onboard wattmeter (it alternates between the two). This is with a connection to a 100W dummy load. Varying L1 and L2 has no effect on the power reading.
I discovered one mistake: I misread the instructions for winding T4's 5-6 and 7-8 windings. I wound these bare wires through BOTH holes in the core, in a U shape, thus connecting 6-7 and 5-8 (and very possibly all 4 together with a short in the middle - this is what comes of staying up too late working on a project!). I corrected this mistake tonight, but I'm seeing no change on the measured power. Is it possible that this mistake fried something? I never saw any smoke or smelled burned silicon, and the thermal pads on Q7 and Q8 look normal. I have also noticed that if I vary the power adjustment on the front panel while in tune mode, I see no change on the wattmeter. That seems significant. These are the other checks I've done so far, per the troubleshooting instructions: * As far as I can tell, my current limit is set to 2.5A. I have not seen any "high current" warnings. * I am using a dummy load to test, I do not currently have an antenna set up that I can use. I have tried two coax jumpers for the dummy load, both test OK on continuity. No change on power output. * The bottom cover is correctly installed and there are no shorts to it that I can see. * I checked all component values in the RF detector, they are correct. * I examined transformers T1-T4, all appear to be wound and wired correctly. * I checked R50, it is measuring the correct resistance. * I checked for hot components and found none. * I checked visually, but not yet with a DMM, for shorts and opens. I have NOT yet done the following: * Looked for shorts in the LPF or BPF - visual inspection shows nothing unusual. How exactly would I check this section with a DMM? * Checked DC voltages in the transmitter and ALC circuitry - I will need to re-assemble the K2 somewhat before I can do this. * Used the RF probe to trace signal flow. Any further suggestions at this point would be greatly appreciated. I can get access to an oscilloscope if that would be useful. Suggestions of the "check x for voltage/resistance y" would be most helpful (though I realize there is a voltage table in the manual that I need to go through). Many thanks in advance! -- [email protected] (Owen B. Mehegan) 'You write the lie You'd like to be When your life looks like a book you wouldn't read' --Blake Schwarzenbach ______________________________________________________________ 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
