APRS Tracker Top View.

Tracker modules are installed and interconnected on a
proto-typing printed circuit board.
APRS Tracker Bottom View

This shows my method of making one-of-a-kind printed circuit boards. Parts are installed as physically required and to minimize jumpers. Connections are then made by bridging pads together with solder.
Close-up showing GPS engine with 3.3 volt regulator board hot glued to top of large integrated circuit.

GPS lithium backup battery is at upper-right next to
MIM module.

Close up of Motorola MPX5100AP atmospheric pressure transducer. Plastic mounting tab ears have been removed to enable installing transducer where shown.

Circuit board to right of pressure transducer is
temperature sensor interface.

Jumper to left of pressure transducer is for enable/disable of MIM PTT and for manual keying of transmitter when testing.

Orange LED indicates transmitter is keyed.

Completed BEAR-1 APRS Tracker Assembly

Operates and provides position reports down to 4.05 volts DC supply voltage.

Requires 5.15 volts minimum for proper operation of the MIM analog circuits.

Maximum supply voltage is 12 volts.

Supply voltage is choose  for desired RF output power level.
6.5 volts provides nearly 3 watts of RF power - more than adequate for a balloon tracker system.
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