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Tag Archives: K2

KSB2 problem found, and solved

I finally solved the problem with my KSB2 board. It turned out to be a poorly soldered joint on one of the transformers that terminate the filter. I found it by writing down everything I knew about the problem and using that to systematically exclude different elements in the system.

The final clue was that receive audio was poorer through the KSB2 filter than through the variable filter on the RF board. Poorer, but not absent. That pointed me back to the filter.

I was ready to rip the filter out and rebuild it from scratch, but decided to have one more look at all the joints using an X3 magnifier. I could just see that one of the leads from T1 primary had an annulus of solder and that I could see the copper end of the wire. Sussed: I obviously hadn’t fully stripped the insulation when I made the transformer. A continuity tester confirmed the problem: high, but not infinite, resistance.

It was a 5 second job to re-solder the joint: leaving the iron on long enough for the remaining insulation to bubble off. Just for completeness, I re-did all the other solder joints as well.

The result is that the board now works fine. I’m not completely happy with the performance, or of the filter alignment, but that’s for the next post.

More modules built

After a break, I’ve been back building more K2 modules. I’ve built the KIO2, KNB2, KDSP2 and KAT2 modules over Christmas. That’s the lot. All but the KATU module worked straight away, but I’ve got a problem with the latter. I’ve still got to resolve the lack of Mic gain on SSB and absence ofContinue Reading

It’s done, the K2 is complete

At least as far as the basic unit anyway. After getting over the VCO problem, I’ve been able to make steady, if slow, progress towards completion. The filters are only roughly peaked because I don’t have an RF signal generator. I will rectify that later as my next project is to build an RF signalContinue Reading

Making progress again

OK, we got past the problem with the VCO. After tracing through the signals, I checked the levels on DIN and CLK against the indicative levels in the manual. They were the wrong way up! At this point I got on to the Elecraft mailing list and started asking questions. Luckily, Don Wilhelm W3FPR wasContinue Reading

Debugging the VCO part 2

After spending a bit more time this evening, it appears that the MCU is working OK. I can see logic level changes all the way through the chain from the MCU, via the PLL to the Low Pass Filter. That’s as far I got this evening. More to follow.

Ahhh, we have a problem

Testing the K2 Resistance checks Pass Assemble the Case and plug in the Front Panel and Control Board. It’s starting to look like a radio now. Isn’t it small! 4MHz Reference Oscillator Calibration Check The target is 12090 kHz +/- 30 kHz. Mine is running at 12099.45. Pass. PLL Reference Oscillator Range Test. Target rangeContinue Reading