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Sunday, June 2, 2013

Simple Homebrew SDR

I know that "simple" and "homebrew" aren't the words that come to mind when we think of Software Defined Radios, but minimalist guru Peter Parker, VK3YE, reminds us that with little more than an antenna, a diode, a crystal oscillator and a connection to the computer soundcard, you can dive into the world of SDR. 

I've been doing this for some time now, but my receiver uses a 40673 dual gate MOSFET and a universal VXO from George Dobbs, G3RJV.  I've been running mine with the FLDIGI and JT-65 HF programs.  Peter's video alerted me to the charms of SDRadio from Alberto, I2PHD.  This is a very nice program.  Of course, I'm always happy to add a dash of Italy to my operations.  Thanks Peter!  Thanks Alberto! Thanks George!

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  1. Cool! Where does Peter show us that minimal SDR front end? I can guess the schematic but if he posted something on his site I couldn't find it. A stage of gain would certainly be called for, but that could be minimal too.

    I'd be fun to try that with fldigi on a Raspberry Pi or Beagle Bone Black, or even bare-bones on an FPGA.

  2. Mike: That image in the blog post is a video from Peter. He shows the schematic during the video. It is just an LC front end filter to a diode, with the output from a Colpitts osc driving the diode as a mixer. That's it! AF from the diode goes to the sound card -- Alberto's program does the rest!
    73 Bill

  3. Duh! Didn't notice it was a video, thanks. I love this minimal radio topic, always have. Back in college we hooked a wire up to one input of a logic gate with a pulse generator on the other input. It could tune in local BCB stations, ugly sound but minimal.


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