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Using the GST-1 with: THD-7A, PalmPilot III or PacComm Hardware Single Port switch
Return to the main GST-1 page.

The GST-1 normally derives its power from the computer serial port. Some devices do not have the control signals available from which the GST-1 derives its power while other devices, switch the control signal power off and on at various rates or simply do not supply sufficient power for the GST-1.

This FAQ discusses the problems involved and their solutions.

In the case of devices which switch the RS-232 control lines off and on, normal operation of the Earthmate is interrupted every time the line switches. This forces the Earthmate to restart every time. The result is that the Earthmate will never acquire enough satellites for a position fix.

Devices which do not supply the RS-232 control signals can not power the GST-1 and thus the Earthmate will never turn on.

The Solutions:

There a couple of different solutions to the above problems:

  1. The GST-1 may be powered with a 9V battery connected between pin 5 (Negative) and Pin 6 (Positive) on the GST-1 female computer connector.
    Do not ever apply 9 volts to pin 9 of the GST-1 or directly to any pin on your Earthmate. To do so will probably destroy your Earthmate.
  2. DeLorme offers an external power adapter for the Earthmate. All GST-1's currently being shipped are capable of receiving power from the DeLorme power adapter, as well as from a serial port.

The following information is provided without warranty of any kind. To the best of our knowledge it is correct but it is your responsibility To verify the information. We can not accept any liability for the consequences of the use of this information.
For those of you interested in building your own Earthmate external power adapter, you can do so quite reasonably.

Simply put, the Earthmate Power adapter supplies +6 Volts to pin 9 on the Earthmate connector with pin 5 being ground.

A simple male to female DB-9 connector with pins 2, 3, 4, and 5 wired across Between the male and female sides provides the signal paths for all required Earthmate signals. Providing +6V to pin 9 of the (male DB-9) Earthmate connector. The negative side of the supply connects to pin 5.

The required 6V can be derived from 12V by using a 6 Volt 3 terminal regulator such as the LM7806 or similar device. DO NOT USE a LM78L06 as it can not handle the power.

Return to the main GST-1 page.

* Earthmate is a trademark of DeLorme.