[aprssig] REVIEW: Way Cool Gadget! Wrist Wearable GPS is great with TH-D7, TinyTrak or PocketTracker!

Stephen H. Smith WA8LMF2 at aol.com
Fri Aug 27 05:45:37 EDT 2004

Excerpt from the full review, with more information and photos, posted
on my website at:

Garmin ForeTrex 201  "Personal Navigator"  Wrist GPS

This GPS receiver may well be the ultimate accessory for the Kenwood
TH-D7 APRS hand-held radio.  The TH-D7 has a serial data input jack for
transmitting position reports provided by an attached GPS receiver.
However most GPS devices are nowhere near as conveniently portable as
the Kenwood radio.

The Garmin ForeTrex 201 "Personal Navigator" is a miniature GPS receiver
that you wear on your wrist like a watch.  The device is secured to your
wrist with a Velcro strap and is powered by an internal rechargeable
lithium-ion battery.  Specs in the manual say the battery will power the
unit for up to 15 hours.   The unit is WAAS-enabled.  The built-in patch
antenna is astonishingly sensitive. I found that it worked quite
consistently while walking with my arm by my side, with no special
efforts to orient the unit favorably to the sky.  It even worked inside
the car as long as I wore it on my left hand and kept my left hand on
the steering wheel. ( I assume one would have to wear it on the right
hand to get the same results in the U.K!) The unit lists for USD $179
but I got mine through an Internet mail-order dealer for $135 .

The ForeTrex works perfectly with the TH-D7, D700 and virtually all
moving map programs running on PCs . I have tested it with Delorme
Street Atlas,  Topo USA!, UI-View, APRSplus, Visual GPS and others.

The main connection issue is that, like the Radio Shack Digitraveller
GPS, the unit's serial port won't start talking until it sees a non-zero
voltage on  the data input pin.  Any voltage, positive or negative, of
more than about 1 volt on the input pin will turn the serial port on.
In other words, you can't use a simple two-wire (TXD and GND/COMMON)
       This presents no problem with either a PC or a TH-D7, both of
which present a non-zero voltage (most PC ports are quiescent at -8
volts or so while the TH-D7 presents  +5 volts out). This is a problem
with the TinyTrak since it's data output line is set to zero volts
during normal operation (i.e. when not being programmed).   Probably the
simplest way to handle the TinyTrak is to apply +5 volts from it's
internal regulator through a 1K resistor to the data input line of the

Stephen H. Smith                   wa8lmf (at) aol.com

Home Page:                            http://wa8lmf.com

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