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Building a tracker from an Old Delorme Tripmate GPS

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Please note that the Tripmate is discontinued...
you can use an Earthmate with signal conversion.

The following describes a Tracker setup using a Delorme Tripmate GPS. It can be used with any SMALL APRS capable TNC such as a TinyTrakII or a MIM.. Any HT can be used as the transmitter.

First off, this plan will change and reuse the DB9 connector and wiring of the Tripmate. The NMEA data will no longer be available at the DB9 connector. This was not an issue for me as I purchased the Tripmate for Tracker use, not to use with my laptop and Street Atlas program.

The goal of this project was to build the smallest Tracker I could. It can all be completed with a few scraps of wire and some shrink wrap.

Open the Tripmate case and pop out the battery carrier. Do the power mod on the Tripmate, this regulator will then supply the GPS, Hold Off circuit and the TNC. Also, you need the space for the Hold Off circuit and the TNC Board.

All the connection points you need on the Tripmate are located along the edge of the board where the connector and cable are now attached, we're just going to rearrange the cable. So, disconnect all the wires from the board (Except the power in from the new regulator of course).

Delorme Tripmate GPS Wiring

I used two RJ45 telephone connectors between the GPS and TNC/Hold Off so I can separate them and work more easily on the unit. One connector carries ground, 5 volts, audio out from the TNC, PTT to the radio, and audio from the radio to the Hold Off circuit. The other connector carries ground, serial data out of the TNC, and Serial data into the TNC. This second connector is easily used to hook the MIM to a laptop for programming. I made up another cable with a RJ45 plug on one end and a DB9 on the other, this goes direct from the MIM to the Laptop serial port.

Here is the overall wiring diagram.

Here is the diagram for the Hold Off section.

Jan. 21, 2002