On Christmas Eve, I was sitting at my in-laws’ kitchen table with the Small Wonder Labs SW-40 I built as a high school kid in 1998 listening to beautiful music and I got the itch to come up with a radio smaller (and less expensive) than the K3 to drag around with me when I go places. My mind wandered to the NorCal Sierra, which was a featured project in ARRL Handbook’s of my youth. I was able to come up with a draft version of that Handbook article on the web—pause for a moment and think how revolutionary that is—my in-laws don’t have an ARRL Handbook, let alone the one that contained the Sierra article. I looked at the bill of materials and realized that I had some 70% of the parts in my junkbox. This seemed like a good idea until I went searching for a PCB.
Why PCB? Well, I’ve done the dead-bug thing and it works great but it’s a pain to troubleshoot and unless you have decades of experience doing it, it looks like a Mexico City suburb, sprawling unpredictably in every direction with only the most tenuous connections to the core. Since I was seeking a travel radio, I wanted it to be compact, easy-to-troubleshoot, and relatively rugged. Due in no small part to the wishes of the Sierra’s designers (not coincidentally founders of Elecraft), boards are no longer available. I looked into doing my own board, but if you don’t mix chemicals yourself, you’ve suddenly spent $150 on PCBs, plus the layout effort. I toyed with making the board smaller (a win in several ways) by using surface-mount parts but even that was a non-starter since my junkbox parts are through-hole, requiring me to buy everything.
Astute readers can extrapolate what occurred next. I went to the Elecraft web site to price the Sierra’s successor, the K1. I had all but made up my mind to sell off some junkbox items and raise the capital to buy a K1 kit when something occurred to me: fellow ham blogger Mike, VE3WDM, had recently moved to a smaller QTH and was offering a half-completed K2 kit for sale. His asking price was only a little more than the K1 kit with some of the options I wanted and it was all-band. The ad had been posted for some days by this point, so I fired off a sheepish e-mail to Mike asking if the radio was still available. It was. We sealed the deal and the radio made the somewhat tortuous ride (for us, not the radio—it sat in Chicago for two weeks) from his QTH to mine via the postal system.
I would not have bought a partially-finished kit from just anyone. However, since this was Mike’s second K2 build and he was documenting it carefully in a blog, I figured it was a pretty safe bet. So far, that is definitely true.
While I was eagerly awaiting the radio’s arrival, I redoubled my efforts to get a friend’s TS-930S off of my workbench, a task that involved replacing all 115 electrolytic capacitors on the cookie-sheet-sized “Signal Unit” board (similar to the K2 and K3 “RF unit”). That radio still has low drive (it has ALC again and sounds like a million bucks), something I traced to a hard-to-find semiconductor that’s now on-order. So, I gathered it up and started work on the K2 on Sunday afternoon.
Last night, I got it on 40 meters RX-only and peaked up the RX BPF. Former K2 owner KL9A mentioned to me that it has some blow-by on strong signals but that he thinks it’s a pretty good radio. I can confirm that based on my experience last night. It sounds really really good on CW.
More on the build to come…including a look back at some troubleshooting of the BFO circuit.