UNDERSTANDING THE MEASUREMENTS
Wind Speed - average over the previous three seconds. The measurement will be accurate
for air ow through the front or rear of the unit.
Maximum Wind Gust - maximum 3 - second wind speed since the unit was turned on.
Average Wind Speed - average wind speed since the unit was turned on.
Temperature - instantaneous temperature of the thermistor, which is located at the end
of the long coiled leads in the open cavity below the impeller. The exposed thermistor will
respond quickly to changes in temperature when air ows past it. For fastest response, either
hold the unit into the wind or wave the unit side to side for 15 seconds. Readings should be
taken in the shade. Water and snow temperatures can be taken by hold the unit in the water
or snow.
Wind Chill - combination of wind speed and temperature, as dened by the US National
Weather Service. Wind chill is the effective temperature on a human or animal at low
temperatures due to wind speed. Wind chill readings will be the same as the temperature
readings above 45ºF or below 3 mph.
Altitude and Barometric Pressure - the Kestrel 2500 will measure station pressure in order
to calculate barometric pressure and altitude. Changes in either air pressure or altitude will
affect these readings, so it’s important to make adjustments as necessary.
First, you will need to obtain either (a) the current barometric pressure or (b) the altitude of
your location. You can obtain your current barometric pressure by contacting a local airport
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or weather service. Set this value as your reference pressure on the ALTITUDE screen to
determine your altitude. Otherwise, you can obtain your altitude from a topographic map
or local landmark. Set this value as your reference altitude on the BAROMETRIC PRESSURE
screen to determine your barometric pressure.
There are two examples for when and how to use the BAROMETRIC PRESSURE and
ALTITUDE screens.
First, assume that you know the altitude from one of the sources above. Set the reference
altitude on the BAROMETRIC PRESSURE screen to this elevation. As long as you remain
at home, you can accurately track changes in the barometric pressure. However, the
measurement on the ALTITUDE screen also changes. This value will uctuate as pressure
fronts pass through your location. Since you know your house in not changing elevation, you
can ignore this screen.
Now let’s assume that you are planning a day hike and you’d like to track your altitude.
Before starting, you’ll need to adjust the reference pressure on the ALTITUDE screen. You
can do this by simply adjusting the reference pressure until you reach the elevation of your
house. The reference pressure will be the same as the pressure reading on the BAROMETRIC
PRESSURE screen. You can now track the altitude as you hike. You can ignore the values on
the BAROMETRIC PRESSURE screen, since the pressure changes are predominantly due to
changes in elevation.
As with all pressure altimeters, it must be assumed that any change in pressure due to
weather is small over the course of one day. If you were to encounter an elevation landmark,
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you can adjust the reference pressure until the altitude matches the landmark elevation. This
will correct the altitude for any pressure changes due to weather.
MAINTENANCE & TROUBLESHOOTING
Environmental
Every Kestrel Meter is fully waterproof and oats, and has passed mil-spec drop testing.
Storing Your Kestrel
Avoid storing your Kestrel where it will be exposed to temperatures below -30°C [-22°F] or
above 60° C [176° F] for extended periods of time. Doing so may cause permanent damage.
(Note that the inside of a car parked in the hot sun can reach very high temperatures.)
Use of the Lanyard and Cover
The cover can be captured on the lanyard to avoid loss. First, remove the cord poplock. Then
feed the lanyard end through the large opening in the over and
out the slot. Replace the poplock on the lanyard.
Replacing the Battery
When your display becomes dim or disappears, replace the
battery. Use a large coin to open the battery compartment. Use
only new CR2032 coin cell batteries (available where watch
batteries are sold). Wipe the battery clean of any ngerprints
and insert the positive (+) pole up, angling the battery
Replacing the Battery
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downward and pressing it rmly into place. When replacing the battery door, be sure to keep
the black rubber o-ring seated in the groove on the case back.
Why does the Impeller Appear Imbalanced?
It is NORMAL for the impeller to oscillate as it comes to a stop. It is NOT imbalanced. Rather,
it contains a very small magnet that responds to the earth’s magnetic elds. This does not
affect the accuracy of the wind speed readings because the magnetic eld applies both a
braking and an accelerating force which cancel each other. The impeller has been calibrated
to provide wind speed readings accurate to within at least ± 3%.
High Speed Use
After several hours of sustained operation over 25 M/S (~49 KT, 90 KM/H, 56 MPH or
4,923 FPM), the Kestrel will lose some accuracy due to wear of the sapphire bearings in
the impeller.
Replacing the Impeller
You may recalibrate the wind speed readings by replacing
the impeller. Press FIRMLY on the sides of the black impeller
housing with your thumbs to remove the entire assembly.
When inserting the new impeller, be sure the arrow is
facing the display side of the unit, and is aligned with the
top of the meter. Press on the sides of the housing rather
than the center.
Replacing the Impeller
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