Jon, You have the KPA100 removal steps correct, but I suggest that you do not do that yet. Instead do a quick test - remove the APP connector from the KPA100 and power the K2 from the coaxial power jack.
Then set the power at 5 watts and measure the power output with your external wattmeter (connected into a dummy load). Do the same but with the power set to 2 watts. Did you get 10 or 12 watts in both those tests? Or did you get something close to the requested power? If your actual power was much greater than the requested power, the most likely cause is that diodes D16 and D17 in the KPA100 wattmeter have been damaged. Remove the KPA100 physically and repeat the test with the coax to the wattmeter connected to the BNC ANT jack on the base K2. If you have normal power control, then the KPA100 wattmeter diodes are the culprit. Those diodes are used for power control when the KPA100 is installed, and if damaged, the K2 and KPA100 will go to full power output which will likely put it into a non-linear condition. The other thing that will cause distortion in SSB is the KPA100 ribbon cable and speaker cable - if it is close to the KSB2 board, some coupling can occur. To easily position the cables, remove the right side panel and tuck the cables into the space behind the heat sink and at the top of the control board. Keep the cables as far away from the KSB2 board as possible. 73, Don W3FPR On 3/27/2011 2:11 PM, Jon Perelstein wrote: > I would like to put my K2/100 back to a basic K2 as part of debugging some > problems I've had around power and RFI distortion. I have the K2, KPA100, > KSB2, and KNB2 installed. My plan is to only remove the KPA100 at first to > see if that corrects the problems I've been having. > > As I understand it, removal of the KPA100 involves only the following: > > 1. Disconnect the ribbon cable that goes between the KPA100 and P4 on the > control board > > 2. Disconnect the Aux 12v connector that goes between the KPA100 and the > Aux 12v jack on the main board > > 3. Disconnect the Aux RF connector that goes between the KPA100 and the Aux > 12v jack on the main board > > 4. Disconnect the SPKR connector that goes between the KPA100 and the SPKR > jack on the main board > > 5. Install the SPKR connector from the original top cover to the SPKR jack > on the main board and screw on the original top cover (in an > uncharacteristic fit of planning, I did keep the original top cover). > > 6. Uncover the BNC RF out jack on the K2 base and use that in place of the > SO-239 on the KPA100. > > My original top cover did have the KIO2 installed for interface to the > KAT100, and it is my understanding that I can simply plug that into P4 on > the control board. > > Is there anything else I need to do? > > For reference, my problems at the moment are as follows: > > 1. I get RFI distortion on digital and SSB on the lower frequencies (40 and > 80 meters). I get the distortion when feeding the K2 directly into a dummy > load and I get it when feeding the K2 into a Buddipole about 100' from my > shack. I do not get the distortion when running an FT-897 in similar > circumstances. > > 2. The output power is not consistent. On tune, my MFJ 941E and Elecraft > W1 usually read about twice what the K2 says it is outputting (about 20w). > On CW, the readings per the MFJ and W1 disagree with what is dialed into > the K2 although the amount and direction of the difference varies by band. > > 2. Going straight into a 50 ohm dummy load, (no MFJ, no W1), the K2 is > reading SWRs of 5: or 6:1 in tune mode. When I put the MFJ and the W1 in > the line, they both read 1:1 even though the K2 continues to read 5: or 6:1. > > I believe that the MFJ and W1 are reasonably accurate based on testing > against other devices. > > Thanks, > Jon > KB1QBZ > ______________________________________________________________ > 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 > ______________________________________________________________ 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
