Single Tube SDR Is a Delightful Mix of Old and New

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The one-tube radio setup, in front of a PC monitor

Software Defined Radio (SDR) is the big thing these days, and why not? A single computer can get rid of a room full of boat anchors, and give you better signal discrimination than all but the best kit. Any SDR project needs an RF receiver, and in this project [mircemk] used a single 6J1 vaccum tube to produce an SSB SDR that combines the best of old and new. 

Single-tube radios are a classic hack, and where a lot of hams got started back in the day, but there is a reason more complicated circuits tend to be used. On the other hand, if you can throw a PC worth of signal processing at the output, it looks like you can get a very sensitive and selective single-sideband (SSB) receiver. 

The 6J1 tube is convenient, since it can run on only 6 V (or down to 3.7 as [mircemk] demonstrates). Here it is used as a mixer, with the oscillator signal injected via the screen grid. Aside from that, the simple circuit consists of a receiving coil, a few resistors and a variable capacitor. How well does it work? Quite well, when paired with a PC; you can judge for yourself in the video embedded below.

Weā€™ve featured a lot of [mircemk]ā€™s projects over the years, like this handsome OLED VU meter, or this frequency analyzer with a VFD  and even a virtual pinball cabinet made from scraps, among many others.



from Blog ā€“ Hackaday https://ift.tt/TKkEM5c

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