From: SM4MNC, Leif Hoffmann
I have just finished building K2 #7836. A very great pleasure and about a ton of fun too, and I sincerely hope that this "100% solder kit" will remain in the future! My kit was from the summer sale and contained the K2, the SSB- module, noise blanker and antenna tuner. Everything went almost flawless: Under Alignment and test, Part 2 there was absolutely nothing to be heard in the headphones! What now? The problem solved itself when I found the bag with the surface mount IF-amplifier U12. The step to mount it was described in the errata and I had just missed that small detail! When installed, there were no more problems here. I did the initial adjustments, the transmitter and receiver were functioning - perhaps the filters did not match perfectly, but that was a "software-problem" to be solved later! The SSB-unit, noise-blanker, and finally the antenna-tuner were built and put in the radio, and everything seemed to work as it should. What an amazing little radio this is!! Two more things: 1. In my K2 there is absolutely no space between the encoder and the front panel. Not even the best flush-cutter in the world will give enough space there. I have read in the Elecraft Archives of paper-bits etc. I have put on double layers of adhesive tape (tape for electrical purposes) with the advantage that it doesn't get dislodged when you remove the control board next time. 2. During the assembly there were some very small (in value) capacitors, that in my kit not were similar to the pictures in the parts list, but thanks to Stephanie, Leony, Johanna and all the other packers of the subassemblies, I could simply rely on the number of the remaining parts (no more - no less) and after a little examination of the parts, the problem got a solution and as the radio is functioning, it seems that I have got all parts in the right places! Overall I can say that building the hardware actually were "the easy part" and I have learned a lot in the process. Thanks, Elecraft! BUT: I have read, and re-read many times both in the main manual and the manual that comes with the KSB2 concerning the adjustments. The envelope with the filter crystals for the KSB2 were marked E850006 and 3228-1, 180611. I could not recognize any of these as a calibration number between 3.2 and 3.9, so I used 3.6 as described, and when I came to the filter setup I did exactly as shown in table 3 - with catastrophic result !! The FL1 - under OP1 and LSB- were so high-pitch that it was practically useless, and this is the filter-setting that I probably will use the most! With an antenna and the loudspeaker mounted I adjusted the freq. to more like 4914.1 - 4914.2 than the 4913.5 that comes from the table. The ideal would of course be to sweep the filters with appropriate equipment - which I have none! So that now I have all the filters (both for SSB and CW) adjusted "by ear". I do have a radio that I can use, even if it's not optimal. It's pleasant to listen to and a couple of good reports "on air" too. I just wonder: How many of the previous kit-builders have experienced the same problems - and done what I have done? Finally: How accurate are the settings over time? The 4 MHz oscillator on the control board is of course the most critical part here. But - yesterday evening I had the radio adjusted to within +/- 10 Hz compared to my big transceiver. When I turned on the K2 today it was about 320 Hz high. I have - again - re-run the frequency calibration procedure, the CAL PLL and now again the display shows inside of +/- 20 Hz. Can this be a temperature problem? It was rather warm in my shack yesterday and pretty cold today when I came in. The small capacitor C22 is of course critical here! And a small suggestion: The adjustment would be much more calm if there were two trim-capacitors. One 8-50 pF(as C22 is), and in parallel with that another adjustable capacitor on 1-2 pF for the fine-adjustment. Naturally, I don't expect this little radio to have the same stability as my big radio, with its X-tal oven and that can zero-in on WWV to within +/- 1 Hz, but on the other hand, I don't know what to expect from the K2. Will it be within +/- 10 Hz, +/- 100 Hz or perhaps +/- 500 Hz? How will it perform under field conditions? Actually, it is not that very important, as long as my #7836 performs "as expected". Can you say anything about what stability I can expect from a K2? Yours, SM4MNC, Leif ______________________________________________________________ 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]
