Who has never dreamed of transforming his smartphone into Super Talkie-Walkie Capable of communicating even when the mobile networks are HS? Well it is now possible thanks to a project open source baptized KV4P HT Who will delight all budding radio amateurs!
VANCE VAGELL (indicative KV4P), the creator of the project, had the brilliant idea of designing a small module that simply plugs into the USB-C port of your Android smartphone to transform it into a real bidirectional VHF radio. No need to carry around bulky radio equipment – your phone becomes your radio!
The project is entirely open sourcefrom the electronic card plans to the source code of the Android application, including the 3D printing files of the case. And the best in all of this? You can build your own HT KV4P for less than $ 35 in components.
This small module has nothing to envy to professional radios:
- Crystalline vocal communication Thanks to a 44khz 8-bit audio converter with filters
- Text messaging SMS manner via the APRS protocol (1200 BAUDS)
- Scanning unlimited frequencies with group management
- Intuitive interface directly in the Android app
- Minimum consumption phone battery (1W in emission)
- Accessibility options Like live subtitles
And as a small diagram is better than a long speech, here is a video demonstration:
Level components, it’s rather simple: you need a SA818-V radio module (count around € 9), an ESP32 card with USB-C (around € 3), and a male SMA antenna. For the antenna, you have the choice between a Pocket version at € 5 or a more efficient Stick Stick Signal at 22 €. In terms of USB-C connectors, I advise you to invest in a short cable with adapter (around € 10), but you can also opt for a small ALIEXPRESS connector at € 3 if you want to save.
The heart of the project is the v1.7b printed circuit which will cost you around € 5. You can order it at JLCPCB or PCBway with the files provided in the project. For fixing, provide adhesive pads at € 1.
The assembly is quite direct: you weld the three main components (the SA818-V module, the ESP32 card and the SMA connector), you print the 3D box (and there, you can let go of the two-color for style!) , then you assemble everything. The circuit must fit into the case with a satisfactory click. Then stick the module on your phone’s back with the adhesive pad, screw the antenna, and it’s almost finished!
Software side, it’s just as simple: download the KV4P HT application to the Play Store, launch it and let it flash automatically the firmware (count 5-10 minutes). After that, you can configure your favorite frequencies and channels.
Some tips to optimize your use: Use the 3D stand to keep the vertical antenna on your desk, play with audio filters to improve sound quality, and organize your channels in groups. Do not hesitate to test different antennas according to your needs, it can really change the gaming level.
CAUTION: Important legal point! You absolutely must have a radio license to legally use this equipment. And like any self-respecting DIY project, it is provided without guarantee. The scope will depend a lot from the antenna you choose, and some phones may have USB compatibility concerns.
For a small budget of around $ 35, you can transform your smartphone into a real Amateur VHF radio. This is the perfect project to discover the exciting world of radio while having fun with electronics and 3D printing!
A big thank you to Lorenper for sharing this superb discovery!
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