Take the leap into Red Pitaya ham radio homebrew. Most of what you need for a DIY receiver or transceiver is on this amazing little device.
The modern architecture for homebrew software defined radio is programmable hardware. Red Pitaya provides the core components – analog digital conversion, FPGA and embedded CPU. The STEMlab community provides working software and FPGA IP. You can figure out the rest and build it yourself. Shown above is a picture of a working standalone 8 watt SDR transceiver made by Wolfgang Kiefer DH1AKF.
But first, let’s take a step back. How does this little lab instrument evolve into a functioning dual channel radio? It all started when Pavel Demin joined the STEMlab ecosystem. Pavel, shown above, is a Russian particle physicist living in Belgium. Interestingly, the Red Pitaya parent company specializes in making high performance instrumentation for particle accelerators. A few years ago, Pavel designed some SDR and related applications to run on the Red Pitaya. You can read his detailed development notes if you are interested, or just this summary of his activities. Here is a video presentation by Pavel himself, which explains everything.
Pavel’s contributions include the STEMlab programs and FPGA code for a variety of different ham receivers and transceivers. More recently, a group of German hams has taken the work further with the development of Charly 25 project.
Red Pitaya Ham Radio Homebrew – Getting Started
You can get started with Red Pitaya ham radio homebrew along two different paths. Your first path is to just do it all yourself. If you download Pavel’s code, you can have a single or dual channel SDR receiver running in a few hours. For the front end, you will need a high impedance to 50 ohm transformer, as well as some low pass filtering to prevent aliasing from local FM stations. A simple 30 MHz low pass filter combined with a 9:1 auto-transformer should do the trick. You can get this to work on any Red Pitaya, with the 14 bit model preferred.
The second path is to select from a number of kits provided. Select from a basic SDR kit which includes the input transformer, or a more complete kit which includes input filtering and a ten watt amplifier. Prices are US$400 and US$780, respectively.