BEAR-2 APRS Tracker
August 2000




During the BEAR-1 flight, the tracker MIM module had problems dealing with the RF energy present in the BEAR capsule (about 8" from the tracker Tx antenna) and RF energy will be even stronger during the BEAR-2 flight with two transmitters operating (the APRS tracker plus the cross-band repeater).

To try and deal with this RF energy, the BEAR-1 tracker was rebuilt for the BEAR-2 flight and the GPS receiver, MIM module and Temperature & Pressure Sensor assembly were enclosed in a copper enclosure for shielding while the transmitter was made a separate unit and enclosed in a separate copper enclosure.

The backup battery & pressure transducer were laid flat against the circuit board, to reduce the enclosure height, and the temperature sensor interface was relocated from a separate circuit board to the circuit board holding the GPS & MIM modules and used for their wiring.

Here's the BEAR 2 Tracker Schematic.pdf

The finished BEAR-2 APRS Tracker

The small black component seen poking through the top cover is the payload container inside temperature sensor. 2 more sensors for outside temperature and the cross-band repeater transmitter heat sink temperature are upper-right.

Upper-left corner is the GPS antenna.

The white connector on the side of the larger enclosure is the Programming Cable connector.

The Red Tx LED is on the right side of the transmitter case between 2 holes for tuning adjustments.

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