3500
Pocket Weather ® Meter
with Backlight
Thank you for purchasing the Kestrel 3500 Pocket Weather Meter. This
instrument will measure the following environmental conditions:
• wind speed • heat stress index
• maximum wind gust • dewpoint
• average wind speed • wet bulb temperature
• temperature (air, water, snow) • barometric pressure
• wind chill • altitude
• relative humidity
Plus additional features:
• clock • 3-hour pressure trend
• data hold function • backlight
• automatic power-down function • waterproof and oats
INSTRUCTION MANUAL
Revised 07/28/10
Kestrel® 3500 Pocket Weather® Meter 3
OPERATION
1. Slide o cover.
2. Turn on. Press the center button (
3. Select operating mode. Press the right arrow (
listed below. Press the left arrow (
order. The instantaneous measurements will be displayed. Each measurement screen
is preceded by a brief hint to clarify which measurement is being displayed. (See
Understanding the Measurements section for more information.)
4. Select the unit of measure. While holding
measure listed below.
pressure rising quickly (rise more than +0.18 inHg)
pressure rising (rise within +0.06 inHg and +0.18 inHg)
Mode Hint Icon Units of Measure
Clock --- --- 12-hr, 24-hr
Wind Speed SPd m/s, ft/min, km/h, mph,
Max Gust SPd
Avg Speed SPd
) to turn on the unit.
) to scroll through the measurements
) to scroll through the measurements in reverse
, press
to scroll through the units of
kt, B
MAX
AVG
m/s, ft/min, km/h, mph,
kt, B
m/s, ft/min, km/h, mph,
kt, B
Temperature dEG C, F
Wind Chill chill
C, F
Mode Hint Icon Units of Measure
Humidity r.h.
Heat Stress Index H.I.
Dewpoint d.P.
Wet Bulb Temp bulb
Barometric Pressure* bAro
Altitude Alt
* Only one of the pressure icons will be displayed, indicating the 3-hour pressure trend.
pressure stable (remain within -0.06 and +0.06 inHg)
pressure falling (drop within -0.06 inHg and -0.18 inHg)
pressure falling quickly (drop more than -0.18 inHg)
%
C, F
C, F
C, F
hPa, inHg
m, ft
Kestrel® 3500 Pocket Weather® Meter 5
5. Hold mode. While holding
The word “HOLD” will blink to indicate the Hold Mode. Press
measurements in Hold Mode. While holding
mode can be useful for taking measurements when unable to view the display.
6. Turn on the backlight. Press
are pressed while the backlight is illuminated, the backlight will remain illuminated for
another 10 seconds. Press
backlight.
7. Adjust the clock. Simultaneously press
blinking, press
Simultaneously press
8. Turn o. Hold
turn o if no buttons have been pressed for 45 minutes.
or
for 2 seconds to manually turn o the unit. The unit will automatically
, press
to activate the backlight for 10 seconds. If
while the backlight is illuminated to manually turn o the
to adjust the clock. Hold
and
to hold the time and all of the measured values.
, press
and
to exit the clock adjustment.
to adjust the clock. While the clock is
or
or
to exit the Hold Mode. This
to adjust the times quickly.
to view the other
or
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 eective 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.
Relative Humidity - amount of moisture in the air compared to the amount of moisture the
air can hold for the given temperature, represented as a percent. Because relative humidity is
also a function of the temperature, the response time will be dependent on the temperature
response time (see temperature section above). Readings should be taken in the shade.
Heat Stress – combination of temperature and humidity, as dened by the US National
Weather Service. Heat stress is the eective temperature on a human or animal at high
temperatures due to humidity. Heat stress readings will be the same as the temperature
readings below 70ºF.
Dewpoint – calculated based on temperature and humidity measurements, as a measure of
moisture content in the air. If the dewpoint is very close to the temperature, the air is humid.
If the temperature and dewpoint are the same, dew will form. If this happens below freezing,
frost will form.
Wet Bulb Temperature - calculated based on temperature and humidity measurements, as a
measure of evaporation rate. If the wet bulb temperature is very close to the air temperature,
the air is humid. Wet bulb temperature is typically measured by swinging a mercury
thermometer with a wet sock on its end for several minutes.
Kestrel® 3500 Pocket Weather® Meter 7
Altitude and Barometric Pressure - the Kestrel 3500 will measure station pressure in order
to calculate barometric pressure and altitude. Changes in either air pressure or altitude will
aect these readings, so it’s important to make adjustments as necessary.
ABOUT BAROMETRIC PRESSURE AND ALTITUDE ADJUSTMENTS
The Kestrel Meter measures “station” pressure, the actual air pressure in the measurement
location, and uses this value to calculate barometric pressure and altitude. Station pressure
changes in response to two things—changes in altitude and changes in the atmosphere.
Because the Kestrel Meter is constantly changing location and altitude, it is important to
enter adjustments or “references” when accurate pressure and altitude readings are needed.
Barometric pressure is station pressure corrected to sea level. In order to make the
correction, the Kestrel Meter needs an accurate reference altitude. Altitude is the height
above sea level. In order to correctly calculate altitude, the unit needs an accurate barometric
pressure reference, also known as an “altimeter setting”. Fortunately, you only need to know
ONE of these values (current barometric pressure or current altitude) in order to set your
Kestrel Meter up to show accurate readings.
Starting with the known barometric pressure for your location
You can obtain your current barometric pressure by checking an internet weather site for
a nearby location, or contacting a local airport. Set this value as your reference pressure on
the ALTITUDE screen to determine your correct altitude: simultaneously press
buttons to adjust the reference pressure. Press
hold
changes in the reference pressure. Simultaneously press
pressure adjustment. Set your Kestrel Meter down on a table and allow the altitude reading
to stabilize. (Note: very small changes in pressure generate noticeable changes in altitude.
or
to adjust the value quickly. You will notice that the altitude will change with
or
to adjust the reference pressure, or
and
to exit the reference
and
In order to provide meaningful readings for activities where altitude changes quickly, the
Kestrel Meter features rapid altitude response. This is why the altitude readings tend to
uctuate by a few feet.) After obtaining a current altitude from the ALTITUDE screen, move
to the BARO screen and enter this value as your reference altitude by following the same
procedure. Both readings will now be accurate.
Starting with a known altitude for your location
You can obtain your altitude from a topographical map or local landmark. Google Earth
is an excellent free program that provides the exact altitude for any given address:
www.earth.google.com/. Set this value as your reference altitude on the BARO screen to
determine your barometric pressure: simultaneously press
the reference altitude. Press
to adjust the value quickly. You will notice that the barometric pressure will change with
changes in the reference altitude. Simultaneously press
altitude adjustment. Again, allow the Kestrel Meter to stabilize, then enter the value from
the BARO screen as your reference pressure on the ALTITUDE screen by following the same
procedure. Both readings are now accurate.
If you are planning a day hike would like to track your altitude, you’ll need to enter the
correct reference pressure on the ALTITUDE screen as described above. You can now track
the altitude changes as you hike. In this instance, you should ignore the values on the BARO
screen, since the pressure changes will be due to changes in elevation far more than to
changes in the weather.
In general, changes in barometric pressure associated with weather changes are small over
the course of one day, but they will aect the accuracy of the altimeter over time. This is
why aircraft reset their altimeters at every aireld by entering the eld’s “altimeter setting”
or
to adjust the reference altitude, or hold
and
and
buttons to adjust
or
to exit the reference
Kestrel® 3500 Pocket Weather® Meter 9
or reference pressure. Accordingly, if accurate altitude readings are your primary interest,
you should reset the reference pressure on your Kestrel Meter regularly. If you encounter
an elevation landmark, you can adjust the reference pressure until the altitude matches
the landmark elevation. This will correct the altitude for any pressure changes due to the
weather. (Or, you can obtain an updated reference pressure from the sources described
above.)
Some nal notes - If you wish to know the actual or station pressure for your location (such
as for engine tuning), simply set the reference altitude on the BARO screen to “0”. In this
case, the Kestrel Meter will not make any adjustment and will display the measured value.
(Engine tuning and ballistics software sometimes refer to atmospheric or station pressure as
“absolute pressure.” These applications are concerned with the actual air density, as opposed
to pressure gradients relating to weather, so barometric pressure is less useful.)
Also, the above discussion applies to ALL pressure altimeters, including one you may have
in a watch or other device, but not to GPS altimeters, which use satellite triangulation to
determine altitude. Note that with present GPS technology, pressure altimeters remain more
accurate for measuring altitude change. This is why airplanes still rely on pressure altimeters,
not GPS.
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
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
aect 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%.
Replacing the Battery
Kestrel® 3500 Pocket Weather® Meter 11
High Speed Use
After numerous 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 pivot
and 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.
Taking Accurate Humidity, Heat Stress and Dewpoint
Measurements
The patented system for measuring relative humidity allows for extremely fast and accurate
readings. The sensor is located in the large hole on the rear of the unit. Even extreme and
abrupt changes in the surrounding humidity will be measured within several minutes. To
test this, place your hand around the rear of the unit. Within several seconds, the humidity
will increase dramatically. After removing your hand, the humidity will quickly begin to
decrease. Next, place your hand near the rear of the unit and wave the unit back and forth.
The humidity will not change because the air ow is diluting the humidity from your hand.
This example shows the importance of keeping air ow past the sensor while taking a
measurement. If there is no natural air ow past the sensor, wave the unit back and forth.
It is also reasonable to lay the unit down on a solid surface for several minutes to allow the
Replacing the Impeller
sensor to adjust.
Sensor Calibration
All the sensors have been factory calibrated to be accurate within specications. For
recalibration, you may either return it to Nielsen-Kellerman for factory calibration, or contact
NK for eld calibration instructions. Humidity Field Calibration Kits are also available for
sale online.
About the Backlight
The Kestrel 3500 has an aviation green electroluminescent backlight. The Kestrel 3500 NV
has a night-vision preserving backlight which helps users to sustain natural night vision.
The NV’s backlight incorporates an optical lter to reduce overall brightness and minimize
blue and green spectrum light to preserve night vision. Additionally, the backlight is much
dimmer than a standard backlight, making it more dicult to detect with the naked eye in
night operations. This backlight appears soft greyish pink (not red) and is still in the visible
spectrum, so it is not compatible with night-vision equipment.
It takes 30 to 45 minutes for the average eye to adapt to darkness and maximize night
vision. Even a short burst of white, yellow, green or blue light “bleaches out” the rod cell
photoreceptors in the eye and causes night blindness until the entire adaptation process can
take place again. Light in the red spectrum does not cause this “bleaching out”, preventing
night blindness and night vision fatigue.
Kestrel® 3500 Pocket Weather® Meter 13
BEAUFORT SCALE
The Beaufort Scale is a system for estimating wind force
without the use of instruments based on the visible
eects of the wind on the physical environment. The
behavior of smoke, waves, trees, etc., is rated on a 13
point scale. The scale was devised in 1805 by the British
naval Commander Sir Francis Beaufort (1774-1857) and
is still commonly used by mariners.
KESTREL POCKET WEATHER METERS
5-YEAR LIMITED WARRANTY
NK does not believe in “disposable electronics.” We
know that Kestrel Meters don’t typically lead pampered
lives, and we design them for years of performance in
Force Description Kts
0 Calm 0
1 Light Air 1-3
2 Light Breeze 4-6
3 Gentle Breeze 7-10
4 Moderate Breeze 11-16
5 Fresh Breeze 17-21
6 Strong Breeze 22-27
7 Near Gale 28-33
8 Gale 34-40
9 Strong Gale 41-47
10 Storm 48-55
11 Violent Storm 56-63
12+ Hurricane 64+
tough conditions. Every Kestrel is designed and manufactured at NK’s facility in Boothwyn,
Pennsylvania, to be the accurate, reliable weather instrument you need for your application.
If for any reason you are not satised with the performance or operation of your Kestrel meter in the rst 30 days, you may return it to your place of purchase for a full refund.
We guarantee every Kestrel Pocket Weather Meter to be free of defects in materials and
workmanship for a period of FIVE YEARS from their date of rst consumer purchase. NK
will repair or replace any defective product or part when notied within the warranty period,
and will return the product via domestic ground shipping or NK’s choice of method of international shipping at no charge.
The following shall be excluded from warranty coverage: damage due to improper use
or neglect (including corrosion); damage caused by severe or excessive impact, crushing or
mechanical harm; modications or attempted repairs by someone other than an authorized
NK/Kestrel repair agent; impeller failure not caused by a manufacturing defect; normal usage wear; failed batteries; and accuracy issues resolvable by recalibration. Recalibration is
provided free of charge within thirty (30) days of purchase if necessary.
Except for the warranties set forth herein, NK disclaims all other warranties, expressed,
implied or statutory, including, but not limited to, the implied warranties of merchantability or tness for a particular purpose. Any implied warranties that may be imposed
by applicable law are limited to the term of this warranty. In no event shall NK be liable
for any incidental, special or consequential damages, including, but not limited to, loss
of business, loss of prots, loss of data or use, whether in an action in contract or tort
or based on a warranty, arising out of or in connection with the use or performance of
an NK product, even if NK has been advised of the possibility of such damages. You
agree that repair, and (upon availability) replacement, as applicable, is your sole and
exclusive remedy with respect to any breach of the NK Limited Warranty set forth
herein. All product liability and warranty options are governed exclusively by the laws of
the Commonwealth of Pennsylvania.
Your warranty period will be measured from your date of purchase. The best way to ensure
full warranty coverage is to REGISTER your NK product promptly on our website: www.
kestrelweather.com. We keep your registration information strictly condential and do
not sell it, share it, or use it for anything but product-related information bulletins (which
Kestrel® 3500 Pocket Weather® Meter 15
you may decline receiving). If you do not register and cannot provide proof of purchase,
your warranty period will be measured from our date of manufacture, determined by serial
number.
We request that you contact NK if you feel your product is not working properly. We can
often solve product issues by phone or e-mail, saving you the time and expense of returning the unit. If we require the product to be returned, we will issue a Return Authorization to
expedite the handling of your warranty claim.
The Kestrel Pocket Weather Meters are covered by the following patents: 5,783,753,
5,939,645, 6,257,074, and 7,059,170.
LIFETIME CUSTOMER CARE WARRANTY
NK wants you to be an NK customer for life, so we take care of you even beyond the terms of
the above warranty with our Customer Care Program. Trade-in any Kestrel Pocket Weather
Meter, no matter the age or condition, and receive a generous discount on the replacement
product (same model only). Our Customer Care Program applies only as long as we
manufacture the product, and does not cover product upgrades.
CALIBRATIONS, CERTIFICATIONS AND SERVICE
Every NK product is tested and calibrated before it leaves our factory. We guarantee that it
will perform within specications when you receive it. Each Kestrel comes with a Certicate
of Conformity, with the stated specications for that product on the back. If you feel an
NK product is not meeting specs when you receive it, call us and we’ll make sure you are
operating it correctly. If it still appears that it may be out of spec, return it to us within 30
days of purchase and we will test and recalibrate all values at no charge. Beyond 30 days, we
oer reasonably-priced tests, calibration services and N.I.S.T. certied calibrations as well as
Kestrel tune-ups.
All of our measurements are traceable to the National Institute of Standards and Technology,
ensuring the highest level of accuracy. Our primary Calibration Standards are sent for
calibration in accordance with N.I.S.T. requirements and based on a regular schedule.
Only approved laboratories and N.I.S.T themselves are used for these calibration services.
Incoming and outgoing data is supplied with the certicate of calibration.
We also oer full factory service on every product we manufacture for as long as we make
the product (and as long after as component availability permits). If we can’t repair a
product, we will oer you a brand-new replacement under our Customer Care Program (even
for accidental damage and misuse).
ADDITIONAL INFORMATION
What is a “Kestrel”? The American Kestrel is the smallest North American falcon.
Beautiful and highly adaptable, it can be found virtually everywhere in North
America. It is unique among falcons for its ability to both hover at very low speeds
and dive at very high speeds.
Assembled in the USA. The Kestrel 3500 is protected by US Patent 5,783,753, 5,939,645 and
6,257,079. Nielsen-Kellerman reserves the right to change product specications. ©2010.
Kestrel, the Kestrel logo, Pocket Wind, NK and the NK logo are trademarks of the NielsenKellerman Co.
Kestrel® 3500 Pocket Weather® Meter
Register your Kestrel® Pocket Weather® Meter online at www.kestrelweather.com.
NIELSEN-KELLERMAN
21 Creek Circle, Boothwyn, PA 19061
Phone: (610) 447-1555
Fax: (610) 447-1577
Web: www.kestrelweather.com
Email: kestrel@nkhome.com
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