Tag Archives: THD7

GPS serial receiver for Kenwood TH-D7

press the pos button while GPS data is running at it will show you the locator,and lat/long, the degree and decimal points flash on reception. With an unlocked GPS it is lat/long of 0

press the pos button while GPS data is running at it will show you the locator,and lat/long, the degree and decimal points flash on reception. With an unlocked GPS it is lat/long of 0

This project is to make something that used to be common – a GPS receiver with serial data output. Modern APRS handhelds like the THD72 have GPS on board, but my Kenwood TH-D7 is from the turn of the century and doesn’t have onboard GPS. I used to pipe the output of a handheld GPS into the serial port. That worked fine, but in the field it’s a drag to use a handheld GPS tethered to a rig. Every time you want to put something down or set the rucksack down you end up with a knitting session on the cables. This is why they invented Bluetooth, and one option I considered was running a little Bluetooth receiver to a Copilot BT GPS. Trouble with the Copilot is how do you recharge it in the field, and I need to pick off power from somewhere to run the Bluetooth receiver. So I still get cables to the rig and another battery to manage 🙁

Most handheld GPS receivers like my Garmin Vista HCx have moved on to USB serial interfaces now, whereas the 1990s vintage Kenwood TH-D7e uses 4800-n-8-1 RS232, which is what GPS units chucked out in those days. Early THD7s had a problem reading the serial stream since NMEA 0183.3 superseded 0183.2 for the reasons described in the Potator article. I assumed my unit was one of these, so I constructed the Potator, but while the rig worked through it, it also worked without it, so I was lucky and dispensed with that 🙂

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