The tracker is a Byonics Pocket Tracker kit from James (VE6SRV) and BEAR's Trimble Lassen LP GPS Receiver in a .010" copper sheet box.

Outside & inside views of the GPS antenna jack & rubber grommet that was placed over it to make the opening somewhat water resistant.

The pocket tracker kit's BNC antenna connector with plastic insulation was replaced with a teflon one that could be soldered to the case to eliminate any mechanical/electrical connection problems plus make the case water resistant as the GPS antenna jack & battery conductor grommets do. These moisture prevention measures and sealing the enclosure lid with tape will hopefully prevent problems like BEAR 2 experienced if a wet landing is ever experienced again. Arrow 1 identifies inductors L1 & L2, and arrow 2 identifies the VCO oscillator coil which are all likely fine being simply soldered in place, but the slightest vibration of these components causes the VCO frequency to shift due to changing capacitance with nearby items and the resulting modulation could possibly cause data errors so these 3 components were mechanically stabilized with hot glue & wax. I used hot glue to stabilize the coil first, but should have used wax to stabilize all three components as it is much easier to work with for this application.

 J9 or Power ON/OFF Jumper

CD -

 Carrier Detect Input Pin. Other pin is +5V.
 Jumper these 2 pins to suppress automatic transmissions while testing, if required.

4Pin -

 4 pin connector strip to power & connect the GPS or connect to a PC serial port.
 Brown is Ground, Red is +5V, Orange is Tracker Data Out, Yellow is Tracker Data In.

J6 -

 Ground & Power Switch Output Pins.
 DO NOT place a shorting jumper on these 2 pins.

Note:
Serial Power Enable Jumper J7 on the bottom of the PCB must be shorted to provide +5V on Pin 3 of the 4 pin GPS connector.

P/S -

 J5 or Primary/Secondary Configuration Jumper.
 Jumper these 2 pins to select Secondary Configuration.

FS -

 J11 or Frequency Select Jumper.
 Jumper center pin and pin next to "9" for 144.390 MHz
 Jumper center pin and pin next to "4" for 144.340 MHz.

 Jumper these 2 pins to keep transmitter on during alignment.

Reverse Polarity Protection Diode Voltage Drop = 0.8 volts.
Voltage Regulator Input-Output Differential = 0.3 volts.

GPS Receiver power is provided by a 3.3 volt linear voltage regulator
connected to the Pocket Tracker's 5 volt linear regulator output.

A Duracell 9 Volt Alkaline Battery provided 5.5 hours of operation during a battery life test with the tracker beaconing once / minute.

The 3.3V GPS receiver requires 64ma which is over 91% of the total tracker battery load with the pocket tracker only requiring a continuous average current of **6.1 ma. so the biggest improvement would be to replace the GPS 3.3V linear voltage regulator with a switching regulator.
(**5ma continuous + the 1.1ma average current resulting from 138ma for 500 msec every 60 seconds while transmitting APRS data).

This is a (National Semiconductor) simple switcher evaluation board after its LM2954 5 volt regulator chip was replaced with a 3.3 volt one. The original capacitors had to be replaced due to excessive ESR also which was likely due to age even though this evaluation unit had never been used. A post ripple filter (inductor & capacitor in upper left corner of photo) was also added and it reduced the output ripple to below a measurable level.

Table 2 lists GPS Receiver required current vs supply voltage using the switching regulator and percent difference from using a linear regulator.

This is how the tracker was powered for SABLE-1, with a switching regulator for the GPS receiver and from an alkaline 9V battery. There was no time for a proper battery test before the flight, but the tracker was used while travelling to Hanna to launch SABLE-1 and it is unclear as to when the tracker actually quit operating, but it appears that a 9 volt alkaline battery will power this configuration for about 6 hours. With less current required at voltages greater then 6.1 volts (minimum pocket tracker operating voltage) it was hoped operation from a 9 volt battery would last a little longer then it appears to have, but exposing the battery to the very high temperature on the car dash that day probably didn't help. No proper battery test of this configuration is planed due to the high cost of 9 volt alkaline batteries plus I want to carry on and also use a switching regulator for the pocket tracker to further increase efficiency.

Some work was also done with this converter which converts 2 to 4.5 VDC from 3 AA alkaline cells, which weigh the same as a 9 volt alkaline battery, to 6.3 VDC. I only had cheap no-name alkaline cells to use for this test, but 3 alkaline AA cells provided 7.8 hours of operation which is a 48% increase in operation time.

Note: This test was done with the GPS still using a 3.3V linear regulator. No further work was ever done with this regulator, but the next step would have been to remove the Pocket Tracker's 5V linear regulator and readjust this regulator to provide 5 volts and further improvement.