It has been a few weeks since I finished the K2 and its SSB board, so I thought I would write down some thoughts for the benefit of other builders.
First, I have to say that my "measure twice, cut once" approach was probably the biggest contributor to my success. I can't stress enough how important it was for me to do the full parts inventory before I started building – I was missing a couple of parts, and Elecraft quickly shipped them to me. I was still able to start building without them, and then I wasn't brought to a standstill later when I got to where they were needed. I double checked each part before placing it, making sure I had the right value, polarity, location etc. And I also checked the board carefully with a magnifying glass before powering it up. On more than one occasion I found parts I hadn't soldered, including an entire IC!
Investing in some good quality tools was also a really good move. The best of the bunch was the Panavise 324 "electronic work center." It's basically a weighted base with two clamping arms that can be adjusted to different widths to hold most PCBs (anything larger than maybe 2-3" wide). With the PCB clamped in, you can have it right side up while you insert parts and bend their leads back, and then quickly turn it over to solder it. It also has 6 parts trays in the base and a solder spool holder. I got that on Amazon I think. I also bought a set of diagonal flush cutters (totally invaluable), a set of different-shaped tweezers, and a set of small screwdrivers, all from Jameco. I was fortunate that my friend Nick was willing to lend me his Metcal soldering station, but I think one of the nicer Wellers (temperature controlled, blue wand) would have worked fine also.
Despite my best efforts, I did make some mistakes building the K2. The first two were on the RF board. After completing it I followed the instructions to align the transmitter, and found that I couldn't get more than 400 mw of power on 40m no matter what I set the power dial to. The first mistake I found, while inspecting my work, was that I had wound the toroid T4 improperly. It uses a binocular core, and the two "linking turns" for it are supposed to just go straight through each hole. I had wired them each through BOTH holes which, I realized later, was stupid because you use bare wire for these. Everything was shorted! But I fixed this and my output power problem remained.
There are 3 holes at the point where C6 is installed. If you are installing the 60m board, a 3 pin header goes there instead. Otherwise, the capacitor's leads need to go in the outer two holes, leaving the center hold empty. I misunderstood both the original instructions and the errata that was supposed to clarify this, and as a result I couldn't get more than 400mw output on 40m. Eventually I fixed this and, miracle of miracles, the K2 worked!
This brings me to the last thing I want to comment on – the wonderful Elecraft mailing list. In addition to official telephone and email tech support, Elecraft also has a mailing list where users of their products discuss them, as well as other (sometimes) related topics. Whenever I had difficulty with the K2 construction, I either searched there and found the answer, or posted a question and got a response quickly. In particular, Don Wilhelm, W3FPR, was a huge help. He was often the first to reply and often had the right answer on the first try.
All in all, the K2 was really fun to build. I started to learn about the electronic theory behind radio, what you need to make one work, as well as just some simple mechanics of kit building that will be useful to me going forward. One of my goals in getting into ham radio was to have an excuse to get BACK into electronics and kit building, so the K2 project has really satisfied that. It has given me the confidence to always want to ask, "Can't I just build one of these myself?"