APRS - GPS - Packet Radio - Ham Radio - Amateur Radio - Tripmate GPS - 2 Meter Radios

Please keep in mind that this modification will not allow you to use your Tripmate with the Street Atlas Software as it was originally designed. I do share plans on how to build an external Tripmate Adapter that will allow you to use your Tripmate with Street Atlas or you can connect it to a Tiny Trak 3 for use with APRS. Also, this modification will void any warranty if you still have one.

I just modified a second Tripmate that I bought through ebay for the price of $42.00 to work with a second Tiny Traker 3 I am building up. Below is just a collection of photographs I took while doing the modification. The total time to perform the mod was about an hour. Plugged it in and it worked perfectly.

Parts List:

1-Tripmate GPS Receiver
1-7805 Voltage Regulator
1-10k ohm 1/8 watt resistor
1-.01uf capacitor
1-10uf / 35 volt capacitor
some black electrical tape
small piece of hook up wire

I haven't measured the current through the 7805 yet, a slightly cheaper 78L05 would work if the current draw is less than 100 ma.

Cut the wires to and remove the battery holder. Toss battery holder into junque box. Remove the white connector and set it aside for now. Remove the three small screws securing the metal plate to the GPS circuit board.

Unsolder the Red, Brown, Black and Yellow wires. Do not unsolder the Orange wire. Cut the Yellow and Brown wire short and tape off. You could save the piece of the yellow wire to re-use as your small piece of hook up wire. Some Tripmates have a White wire instead of a Yellow wire.

Solder the short piece of hook up wire to the pad next to the Orange wire. The other end of this wire will go to the 5 volt output of the 7805 regulator.

On this unit I cut the lead to the 10k ohm resistor and bent it sort of crooked to serve as the jumper across the other two pads where the Brown and Black wires were. The Brown wire has been abandoned and the Black wire is soldered to the other end of the 10k ohm resistor.

I drilled a small hole near where the serial cable enters and pulled the Red wire and the other end of the small piece of hook up wire through this hole. I also mounted the 7805 voltage regulator to the screw next to the white connector. You will need to scrap the "Lock Tight" stuff off from around the small hole where the screw goes so the 7805 lies flush against the metal plate.

I soldered the center "common" pin of the 7805 to the plate along with one lead of the .01uf cap. The other lead to the cap goes to the "output" of the 7805. The Red wire from the serial cable goes to the "input" of the 7805 and the small piece of hook up wire goes to the "output" of the 7805. Replace the white connector in it's socket.

Here I soldered the + lead of the 10uf cap to the "input" of the 7805 and the - lead of the 10uf cap to the metal plate. 

I just copied another 7805 circuit and that's where I got the idea for the capacitors. They may or may not be totally necessary.

Here is an alternate view of the picture above.

Neatly place a few pieces of black electrical tape below the 7805's leads so thing doesn't short out and we're done. I replaced the cover and plugged it into the Tiny Trak 3. After about two minutes to acquire a lock on the satellites I am in business! Outside on the patio table of course.

Remember to jumper across J7 inside the Tiny Trak 3 to provide power to the Tripmate.

73's and hope to see you on APRS soon!

Jerry Karlovich, KD5OM
Email me and let me know if this has been helpful or if you have something different to share.
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