K2 build project: RF board part 3

This will be the final construction post about the base K2! I officially finished it on October 8th by installing the speaker and affixing the serial number sticker to the back of the case. K2 #6991 is born!

The final phase of construction had me installing a bunch more discrete parts, winding the last few toroids, then aligning/calibrating the receiver before I installed the speaker, buttoned up the top of the case, and added the serial number sticker. 

During the alignment phase, I discovered two mistakes. The first step is to align the transmitter on 40 meters. The manual says to set the output power to 2 watts, put the transmitter in tune mode, and adjust two inductors to get the peak power out. Unfortunately, in tune mode I was only seeing 300-400mw, and adjusting the inductors didn't have any effect. During my first visual inspection after uncovering this issue, I realized that I had misread the directions for winding T4, a transformer with a binocular core. I decided to wait until the next day to correct this mistake, because it had gotten pretty late by this time. I came home from work the next afternoon, fixed the T4 windings and put everything back together, but I still couldn't get any more power out on 40m.

My next step was to email the Elecraft email list, and I got a response from Don Wilhelm, W3FPR, less than 8 hours later. After two days of troubleshooting we figured out that I had put C6 in the wrong place on the RF board. There's even an errata about this step, which I dutifully copied into the manual before I began building, but it still wasn't clear enough for me. The issue is that there are 3 holes at the location where C6 goes, and the cap needs to go in the outer pair of holes, with the middle hole left open. Apparently the errata sheet is being updated AGAIN, with a picture this time, to clarify this step once and for all! Once I fixed this I immediately started to get good power out on 40m, and I proceeded through the rest of the alignment procedure with no issues.

Once the alignment was done I put the final cosmetic touches on the rig and it was done! As of now I've spent a number of nights listening on the different bands, getting familiar with the K2's controls and learning my way around the bands. I still don't have a proper antenna setup yet so I have not tried to transmit. Hopefully that will change soon. I also still need to assemble the SSB board, and cobble together a mic cable for the Kenwood MC-50 mic that my friend Rob, AK6L, gave me. Then I can make some voice QSOs, and if I get a SignaLink PC interface I can work some digital modes too. More to come on all this.

 Last of the capacitors and resistors installed.


Transistors and inductors added.


Several more toroids.


All done and installed in the case.


Affixing the serial number sticker.


WWV comes in loud and clear!


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