If you have searched for trackers online, you will notice the cheapest is somewhere around $40, and you still need to supply a GPS. I'll show you how to use a cheap android phone, a cheap Chinese HT, and a simple cable to make an APRS tracker in True Ham Fashion!
|Baofeng UV-5re Plus w/Extended Battery
|Cheap Android Phone
|3.5mm Male to Male audio cable
|APRSdroid Sending location updates
To get started setting up your tracker, put the app on your phone and configure the settings. You will want the app to send updates via AFSK through the speaker/mic on your phone. While you are in settings you will also notice a section to get a passcode for accessing the APRS-IS system, I would follow their instructions and get one. You will probably want it eventually even if it's not necessary for this project. The final setting is for your SSID. I usually use CALLSIGN-7 if I'm using a radio and CALLSIGN-5 if I'm just using the phone stand-alone. By default SmartBeaconing is enabled, and I tend to leave it setup this way.
On the radio, you will want to enable VOX. I usually set mine to a level of 1, but I've heard that it can vary slightly in the cheap HTs. Set your frequency to 144.39 and plug the audio cable from the MIC jack on the radio to the headset jack on the phone.
Once everything is plugged up and the app is running, you can hit the "start tracking" button on your phone. Once GPS reception is locked on and the phone knows where you are, it should send the audio signal to your radio and transmit your current location data.
I've used this method for a while now with really good results. The only limiting factor is battery life. I managed to get about 8-10 hours out of my radio on 4 Watts using an extended battery pack, but the phone won't last long with the GPS turned on full time. Depends on the phone, but if you need longer run time I would suggest getting a bigger power source for the phone and/or radio. Depending on the digipeater coverage in your area, you could also try turning your transmit power down to save radio battery life.