The world's cheapest, lightest, simplest yet most flexible and expansion-capable WSPR high altitude balloon tracker ever! Includes USB interface for configuration, 128K disk, tons of features... perfect for hobbyists, research, education and more.

Offers both a simple-to-use configuration (as simple as just entering your callsign), and much more complex customizability including 19 GPIOs and I2C bus for further sensors and controls. Telemetry uses the QRP Labs telemetry-over-WSPR protocol or you can use CW, FSKCW, DFCW, QRSS, Hellshreiber (standard and slow MFSK), WSPR, JT9, JT65.

Complete end-to-end tracking and data collection is included - create your own flight tracking page on the QRP Labs site with live mapping and download capabilities for your telemetry.

NOTE: the U4B tracker is now supplied with a full-size USB-B type connector, not the previous micro-USB sized connector. Full-size connectors are more reliable and long-lasting. Of course this makes the U4B larger and heavier, but as previously, the USB connector part of the PCB is designed to be snapped off before flight.

List of features: 

• 33.0 x 12.7mm PCB (plus removable protrusion with USB connector)
• Weight: 1.8g (with USB connector protrusion removed)
• Onboard high performance GPS receiver
  
• 32-bit ARM microcontroller running QDOS (QRP Labs Disk Operating System)
• 128K disk (implemented on EEPROM chip)
• 27mW (approximately) transmitter using Si5351A synthesizer
• TCXO referenced frequency stability
• Band coverage 2200m to 2m
• LM75 temperature sensor
• Status LED
• USB interface for configuration, programming and easy firmware update (just copy the new firmware file into the apparent USB Flash drive)
• Free firmware updates for life, when enhancements are developed as the use cases expand