Secondary locating transmitter

A project log for Solar Eclipse High Altitude Balloon

Boulder's makerspace, Solid State Depot, is launching a high-altitude balloon in Wyoming during the Aug 21, 2017 eclipse.

Dan JulioDan Julio 08/18/2017 at 04:070 Comments

Team member Tim Pegg, KF6LHX, designed a 40 MHz ISM band locating beacon to assist in finding the balloon using a directional antenna after it lands.  It is designed to trigger when the balloon falls below around 14,000 feet using a pressure sensor and sends two square wave tones at 700 and 1000 Hz at 40.68 MHz AM modulation.  Power output is estimated to be between 10-20 mW, enough, hopefully for a range of 500-600 feet on the ground for final localization.

Etched circuit board

Directional Antenna (small magnetic loop)