Once the K3 project was built, time was to investigate the softrock lite specifically prepared by Tony - KB9YIG, for the K3 IF. Building the kit is easy with a fresh pair of eyes. But even then, a magnifying lens is a must.
Jack - K8ZOA has made an excellent work to provide an isolating amplifier Z10000, to ensure that a minimum signal from the softrock oscillator is fed back to the K3 mixing stages. I did add to it a bandpass filter, the Z10010, built and tuned by Jack, to eliminate frequency products out of the IF bandpass (400 kHz). Jack's site has a wealth of information on many subjects. His articles have a rarely met attention to detail and completeness! Thank you Jack for sharing all this!
On the left side is the softrock lite and othe right side, the Z10000. Both kits Z10000 and softrock lite were built over a weekend. I put both PCBs in a small housing and attached together the bandpass filter box.
Although it all worked at the first power on, I noticed that I had practically zero image rejection. This wasted me a couple of hours debugging the softrock. As nothing turned out to be wrong, I checked for the obvious: the audio pigtail that connects to the sound card. The right channel cable had a broken solder...
More on testing the panadapter at a later post
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