A low‑cost, permanent WSPR transmit HAT created for and used by the WSPR‑zero project. Designed to be Raspberry Pi HAT–compliant and simple to build, it provides band‑specific low‑pass filtering for clean WSPR transmissions at very low power.
Looking for the full software stack and images? Visit wspr-zero.com and WSPR‑zero on GitHub.
- Raspberry Pi HAT–compliant footprint for Pi Zero, Pi 3, 4 and 5
- Low‑pass filter per band to suppress spurious harmonics
- Pin‑compatible with TAPR WSPR Pi HATs
- Interchangeable on a Pi running either WWoT or the native WSPR‑zero image
- Simple, robust hardware for 24/7 low‑power beacon operation
KiCad/— schematic and PCB layout (generate Gerbers from here)3D-cases/— printable case options sized for SMA and header clearancesLICENSE— see licensing terms for this hardwareREADME.md— this file
- Open the project in KiCad and export fabrication files (Gerbers + drills).
- Assemble the board, populating the low‑pass filter for your target band.
- Inspect for shorts and correct orientation; clean flux residues.
- Mount on a Raspberry Pi GPIO header; ensure SMA and standoffs clear.
- Connect to a 50 Ω antenna system or a dummy load for bench checks.
RF compliance: Use the correct LPF for the band you transmit on. Verify output with a spectrum analyzer if available.
Choose either approach:
- WSPR‑zero image (recommended for a dedicated beacon)
Grab the image and quick‑start at wspr-zero.com/downloads, then configure callsign, grid, band, and schedule.
Time sync matters: WSPR needs accurate UTC. Keep NTP locked or use a GPS‑disciplined source.
- Transmit only with an appropriate amateur radio license for your region.
- Operate within band limits
- Pin‑compatible with TAPR WSPR Pi HATs.
- Built for seamless use with WSPR‑zero and works with WWoT on Raspberry Pi.
Issues and PRs for hardware tweaks, docs, and case improvements are welcome.
- WSPR‑zero website: https://wspr-zero.com
- WSPR‑zero GitHub: https://github.com/zinkwazi/wspr-zero