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TAPR T-238+MODEM2 Kit - A Low-Cost APRS WeatherStation

Parts of this project are no longer available.


The T-238+ is a general-purpose Motorola MC68HC908GP32 microcontroller-based board intended for use with the Dallas Semiconductor 1-Wire(tm) bus and any device that needs a serial connection. The T238+ has been pre-programmed to interface with a Dallas Semiconductor 1-Wire Weather Station Weather data is displayed on an LCD display and transmitted via the piggyback modem in APRS formatted weather packets. The T238+ can also be interface to a computer for data logging.

In addition to being a ready-made kit with the weather application pre-programmed into the microcontroller, connections are provided for simple external debugging and programming hardware for the experimenter to develop applications. Free development environment is available from P&E Microsystems at http://www.pemicro.com/ics08/.

The T-238 kit does not come with an enclosure or power supply. It is left up to the builder to find an enclosure that is suitable. For power, the user can use an ordinary wall transformer ("wall wart") that provides 8-12 Volts DC at 300 milliamps. The T238 is fitted with a 2.1mm power coaxial connector that the center conductor is positive.

The original T-238 was awarded second prize in Circuit Cellar Magazine's - Design99 Contest and was featured in the May 2000 issue of Circuit Cellar Magazine. The T238+ builds on the excellent original design. By adding a modem to the T238, there is no longer a need to add a TNC to the WX station. Just connect the T238+MODEM2 to your radio and you're on the air. Detailed information about the T-238+ can be found at http://www.beals5.com/wx.

T238+ Finished Kit - bottom view

Dallas Semiconductor 1-Wire(tm) Weather Station

Ordering Information

Sorry, T238+Modem2 APRS WX STN is no longer available

Assembly and Operations Manual

The assembly and operations manual can be found online/


The T-238 series was developed by Will Beals, N0XGA, and Russ Chadwick, KB0TVJ.

MODEM2 Kit only

For those who have a classic T238 (non-plus) you may order the MODEM2 kit only to upgrade your T238 Classic. Please be aware that installation of the MODEM2 to the Classic will overlap some of the push buttons used for menu navigation. This will not be a problem if you use switches mounted off the main PCB.

The price for the MODEM2 is:

  • $ 27 US for members of TAPR

  • $ 30 US for non-members

    + shipping/handling if applicable.
(Place Web Order)
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