Hi Don, I got the following results:
1. Base K2 seems to be OK. 2. The KPA100 is upside down next to the K2, and everything is powered through the K2 and its power supply. Using the LP-100 and 50ohm dummy load, the 5W and 10W measurements through the KPA100 check out nominally. 3. When I apply power through the KPA100's power port, and using its power supply, the K2 and KPA100 are dead. The power supply measures about 1.8V when plugged into the KPA100, but ~13.5V with no load. 4. As I mentioned below, I previously checked D9 and D10 and Q5. D10 and Q5 were OK, but I didn't really understand what I saw when I checked D9. From my first post: "I lifted one side of D10, and it seems to test OK, but when I did the same to D9, it looked weird - In "diode" mode, I get .150V in one direction, open in the other. When I test it in resistance, I eventually measure 80-90ohms in one direction (it takes a moment to settle), but it's open in the other. It might be OK?" Next? Thanks. 73, Jim KO5V -----Original Message----- >From: Don Wilhelm <[email protected]> >Sent: Feb 3, 2019 8:50 PM >To: Jim KO5V <[email protected]>, Elecraft List <[email protected]> >Subject: Re: [Elecraft] K2: I killed my KPA100 > >Jim, > >My usual procedure when tackling a problem of that nature is to first >isolate the problem to one component. >You have already apparently checked out the base K2. > >Next, remove the top cover from the base K2 and connect the KPA100 to it >(remove the KPA100 from the EC2 enclosure). >Put the KPA100 upside down on a box or book about 1/2 the height of the >K2 and plug the cables into the K2. > >Then test with an external wattmeter and a dummy load connected to the >KPA100 SO-239 antenna jack. > >First power the base K2 from the 2.1mm coaxial power jack. Check at 5 >watts and at 10 watts - this checks the transmit path through the KPA100 >in QRP mode. Use an external wattmeter and a dummy load. Does the >external wattmeter agree roughly with the K2 display indication and the >power knob setting. > >If you have a much higher actual power level on the external wattmeter, >the KPA100 wattmeter diodes D16 and D17 are the first suspects - replace >them. > >If all is well so far, remove the 2.1mm power plug and power the >assembly with the APP connector on the KPA100. Make the same test. > >After that, check the bias on the KPA100 for a 400ma rise in current >with the K2 set to CW and in CW TEST mode. Hold the mode button until >TEST appears in the LCD, and the CW icon will blink. > >Do a tune and check that the current rise from receive to TUNE is 400ma. > >Then set the power to 50 watts and do a TUNE. Read the actual power on >the external wattmeter. With a TUNE, it should be about 20 watts. > >If it is greater, you have a problem with the KPA100 wattmeter - likely >diodes D16 and D17 have been damaged and need to be replaced. > >More troubleshooting is possible, but that is a good starting point. >If all goes well with those tests, then I can tell you how to check the >KAT100 alone (without the KPA100). > >73, >Don W3FPR > >On 2/3/2019 10:13 PM, Jim KO5V wrote: >> Earlier today, I had been trying to get my computer to talk to the K2 >> through a logging program. After I built the rig, I tested my cables and the >> KIO2 by successfully controlling the K2 with 'K2 Remote', so it was working. >> Today, the logging software would poll the K2, and get no response. 'K2 >> Remote" couldn't see the rig either. The DB9 connector that connects to the >> KIO2 has the cables to the KPA/KAT and serial cable, and I made sure the >> computer's connector was wired correctly for interfacing a "normal" serial >> cable to the KIO2. It all worked. >> >> I looked at the KPA schematic, and thought a diode, or something in the >> current sensing circuit might have failed. I removed Q5, and it tests just >> like my new spare. I lifted one side of D10, and it seems to test OK, but >> when I did the same to D9, it looked weird - but I don't really understand >> that device; In "diode" mode, I get .150V in one direction, open in the >> other. When I test it in resistance, I eventually measure 80-90ohms in one >> direction (it takes a moment to settle), but it's open in the other. It >> might be OK? I hope I didn't kill U7. >> >> I performed the resistance tests in the KPA manual, and they are nominal. Q1 >> and Q2 test OK, and I think Q3 and Q4 are OK. Q3 tests differently than Q4, >> but looking at the schematic, I think what I see makes sense. >> >> It also occurred to me that when I was trying to get the logging program to >> work, I might have caused a failure in my cables while I was hooking and >> unhooking the serial connection. That might have caused a communication >> problem that made the amp go a bit nuts. ______________________________________________________________ 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 Message delivered to [email protected]
