BEAR-1 APRS Tracker
May 2000






APRS Tracker Top View.

Tracker modules were 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.

The Programming Cable connector is the white connector in the upper-right corner of the image.

The GPS lithium backup battery is upper-right, standing up next to the MIM module.

The GPS receiver is at the bottom of the image with the
3.3 volt regulator board hot glued to the top of a large I.C.

Closer View of the
MIM Module and Pressure Transducer area.

Close up of the
Motorola MPX5100AP
atmospheric pressure transducer.

The plastic mounting tab ears were removed so the transducer could be installed where it was.

Closer View of the transmitter area.

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

Left of the pressure transducer is a jumper to
enable/disable the MIM PTT and to manually
key the transmitter when testing.

The Orange LED indicates when the transmitter is keyed.

The finished BEAR-1 APRS Tracker

The minimum supply voltage for providing position reports is 4.05 VDC, however a minimum of 5.15 VDC is required for proper operation of the MIM analog input circuits.

The maximum supply voltage is 12 volts, but transmitter power varies with supply voltage and 6 volts provides almost 2.5 W of RF which is more than adequate for tracking balloons. More cells provide more voltage and output power, but simply adds excess weight and also shortens how long the battery will last.

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