Ken W4KAC tells me that the tuning knob that he used to minimize hand-capacitance effects on his PTO started out as a gear in a leaf blower. I commented that the engineers who designed that gear surely never thought that it would someday be used in a homebrew direct conversion receiver.
Ken lamented the polemical nature of the SSB discussion captured in the above video, but the clip does give a good demo of the SSB capabilities of Ken's receiver. And the video gives some nice close-ups of the receiver itself.
Ken is a CW guy, and he has already homebrewed a QRP CW transmitter that he hope to pair-up with the receiver. Here it is:
Ken reports 160 mW output with a 377 mile reception report on the Reverse Beacon Network. I made a contact with something similar: https://soldersmoke.blogspot.com/2023/02/first-qso-with-high-school-receiver-100.html
Ken wrote about the importance of persistence:
Good morning. Just wanted to say, don't give up if your receiver is not quite right. Mine was working, I even posted a video here. When building the AF amp from the transformer end back, the Q4 stage was fine. I added Q3 and had a "motor-boating" oscillation when I applied a signal. I tore it all off the board and started over. I still had the problem, so being stubborn I continued on and kept adding more filter caps to quiet it down all I could. The receiver worked and sounded pretty good during the day when I copied WA4FAT and others. That evening was a different story when the band was working well and very full of signals. Very strong stations were ok, but I was getting lots of "hash" and noise other than normal band noise. FT8 was breaking through weakly all over the band along with other unidentified stuff. Yesterday morning I grabbed a new piece of copper clad and built and entirely new AF amp. It tested properly all through the build. Instead of installing that board I decided to find the problem with the original. I "thought" I had used new transistors when I rebuilt it the first time. Turns out I had probably put the original Q3 back, because replacing it cured the problem. I had an entirely different receiver last night. A pleasure to listen to. Don't give up like I did at first!!
Ken went the extra mile by building a SECOND Direct Conversion receiver. So he may soon get TWO Hall of Fame credits.
Thanks Ken!
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For more information on how you too can build the receiver:
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Documentation on Hackaday:
https://hackaday.io/project/
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