Kestrel 4500 - Manual (Page 7)

Kestrel ® 4500 Pocket Weather ® Tracker 13
1. Because the Kestrel 4500 is designed primarily to measure wind direction, the digital compass
component is aligned to work with the Kestrel Meter held vertically, in the same orientation used
when measuring wind. As is the case with all compasses, the compass component must be level to
yield accurate readings. To maximize the accuracy of compass readings, the Kestrel 4500 must be
positioned as close to the vertical as possible (front/back and left/right) when using any compass-
related feature (direction, crosswind, headwind, calibration). For every degree off vertical that the
unit is positioned, compass readings may vary up to three degrees.
2. The Kestrel Meter uses two AAA batteries to power the unit. These batteries have a magnetic
signature that can influence the compass readings if not properly calibrated. After installing or
replacing the batteries, you must execute the simple self-calibration routine (see the Calibrating the
Digital Compass section) to ensure that the effect of the batteries is negated. If your unit has not
been calibrated, it will NOT measure direction and will post the message “uncalibrated” at the base
of any direction screen.
3. The impeller of the Kestrel 4500 also contains a small magnet that may slightly influence the
compass readings when the impeller is still or rocking slightly. For maximum accuracy of compass
readings, the impeller should be spinning (or removed).
Taking a Compass Reading
To take a compass reading, simply hold the unit vertical and point the BACK of the unit toward the
direction that you wish to measure. (You can sight through the sensor opening to confirm the direction
alignment.) The unit will display the cardinal direction and degrees.
True vs. Magnetic North - Entering Variation/Declination
“True north” is the northern axis of rotation of the Earth. It is the point where the lines of longitude
converge on maps. “Magnetic north” is the point on the Earth’s surface where its magnetic field points
directly downwards. Magnetic north does not exactly coincide with true north, and its location changes
over time. The difference between Magnetic North and True North is called “Declination” or “Variation”.
These values for your location can be obtained on the internet. The NOAA website is an excellent
resource for this information: www.ngdc.noaa.gov
The Kestrel 4500, just like any other compass, will measure Magnetic North. However, True North can
be displayed by simply programming the Variation for your location. When viewing the Direction in
Magnetic North mode, the display will show “Magnetic North” below the reading. When viewing the
Direction in True North mode, the display will show “True N #.# E”, where #.# is the variation setting.
To switch between these modes, press the button. Then use the and buttons to toggle between
Magnetic and True. To enter the variation for your location, press the button to highlight Variation,
then and to adjust the value.
Measuring Crosswind & Headwind/Tailwind
The Kestrel 4500 automatically calculates crosswind or headwind with respect to a runway or target
direction. To use either of these screens, you must first set the “heading”, or direction of the runway or
target as described below. You then measure the wind in the normal way, pointing the Kestrel into the
wind. The large number shown on the display will be the effective Crosswind or Headwind (depending
on the screen selected) for the target direction.
Note: Tailwinds are displayed as negative values on the Headwind screen. The full value wind speed and
direction are displayed below the Crosswind or Headwind for reference.
To enter the runway or target heading, press the button while on the Crosswind or Headwind screen.
The adjustment screen will always display the Magnetic North heading along the top, even if you have
the Kestrel set to True North. (If you selected True North mode in the Direction screen, this selection will
still be preserved when you return to the Direction screen.) Use the and buttons to select Auto Set
or Manual Set, and the button to enter the selection of your choice, then follow the instructions on
the screen to set the Magnetic Heading either automatically or manually.