A small hardware device for transmitting WSPR messages based on the SI5351 IC. The device has a built-in TCXO to eliminate SI5351 frequency drift, a built-in GPS module for operation with active GPS antennas, transmission time synchronization and automatic QTH locator calculation, and a simple amplifier based on a single BS170 transistor (PCB version 1.0) or buffer amplifier based on a 74ACT244 IC (PCB version 2.0). PCB is made on based on SMD components and adapted for installation in an aluminum enclosure with dimensions 80 x 50 x 20 mm.

The transmitted WSPR message's correctness was verified by decoding the transmission using a locally located Airspy R2 SDR receiver and the WSJT-X application. Also, you can see the results of testing the device during long-distance WSPR message transmission.

RF connectors: SMA
Feed line: 50 Ohm coaxial cable
GPS antenna type: active, external
Maximum output power: ~23 dBm
Supply voltage: 5V, USB-B, fuse-protected
Used PCB Material: FR-4
PCB thickness: 1.6 mm
PCB copper weight: 1 oz

The Firmware folder contains software required for the device operation and firmware instructions. The Schematics directory contains the device schematic file in .pdf format. The Gerbers directory contains files necessary for ordering PCB and side covers fabrication at the factory.

Additionally, you can find information about the list of required components, assembly guide and operating instructions.

A Little WSPR Beacon (Aren’t They All Little?) – Dave Richards AA7EE
Bifilar and trifilar PA
ESP WSPR – Simple and Inexpensive WSPR Transmitter - Ankara Telsiz ve Radyo Amatörleri Kulübü Derneği
FDIM 2024 LOGIC IC TRANSMITTER CHALLENGE - Ankara Telsiz ve Radyo Amatörleri Kulübü Derneği
HarrydeBug/WSPR-transmitters: Arduino firmware for ZachTek WSPR transmitters.
K1FM-WSPR-TX - GitHub
QRP Labs QRSS/WSPR TX Kit
WSPR beacon – Projets radio
WSPR - Signal Identification Wiki

Great thanks to PCBWay for manufacturing the PCBs for the project as a sponsored contribution.

• E-mail: [email protected]
• Telegram: https://t.me/igrikxd
• LinkedIn: https://www.linkedin.com/in/igor-yatsevich/