Apogee TS-100 User manual

APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
TEL: [phone] | FAX: [phone] | WEB: APOGEEINSTRUMENTS.COM
Copyright © 2019 Apogee Instruments, Inc.
OWNER’S MANUAL
FAN-ASPIRATED RADIATION SHIELD
Models TS-100/110/120/130
(including SS models)

TABLE OF CONTENTS
Owner’s Manual ............................................................................................................................................................................... 1
Table of Contents.............................................................................................................................................................................. 2
Certificate of Compliance......................................................................................................................................................... 3
Introduction ............................................................................................................................................................................. 4
Sensor Models ......................................................................................................................................................................... 5
Specifications ........................................................................................................................................................................... 6
Deployment and Installation.................................................................................................................................................... 9
Cable Connectors................................................................................................................................................................... 10
Operation and Measurement ................................................................................................................................................ 11
Maintenance and Recalibration............................................................................................................................................. 15
Troubleshooting and Customer Support................................................................................................................................ 16
Return and Warranty Policy................................................................................................................................................... 18

CERTIFICATE OF COMPLIANCE
EU Declaration of Conformity
This declaration of conformity is issued under the sole responsibility of the manufacturer:
Apogee Instruments, Inc.
721 W 1800 N
Logan, Utah 84321
USA
for the following product(s):
Models: TS-100, TS-110, ST-110, ST-300
Type: Fan-aspirated Radiation Shield and Temperature Sensor
The object of the declaration described above is in conformity with the relevant Union harmonization legislation:
2014/30/EU Electromagnetic Compatibility (EMC) Directive
2011/65/EU Restriction of Hazardous Substances (RoHS 2) Directive
Standards referenced during compliance assessment:
EN 61326-1:2013 Electrical equipment for measurement, control and laboratory use –EMC requirements
EN 50581:2012 Technical documentation for the assessment of electrical and electronic products with respect to
the restriction of hazardous substances
Please be advised that based on the information available to Apogee Instruments from the raw material suppliers,
the products manufactured by Apogee Instruments do not contain, as intentional additives, any of the restricted
materials including cadmium, hexavalent chromium, lead, mercury, polybrominated biphenyls (PBB),
polybrominated diphenyls (PBDE).
Further note that Apogee Instruments does not specifically analyze raw materials or end products for the presence
of these substances, but relies on the information provided by the material suppliers.
Signed for and on behalf of:
Apogee Instruments, May 2019
Bruce Bugbee
President
Apogee Instruments, Inc.

INTRODUCTION
Properties of materials and nearly all biological, chemical, and physical processes are temperature dependent.
Temperature is also a fundamental weather variable. As a result, temperature is perhaps the most widely
measured environmental variable.
Fan-aspirated radiation shields are designed to shield temperature and humidity sensors from incident solar
radiation while maintaining equilibrium with ambient air through active aspiration by a fan. Typical applications of
fan-aspirated radiation shields include air temperature and humidity measurements in weather networks, often
for weather forecasting. In addition, air temperature and humidity are critical input variables for calculation of
evapotranspiration and irrigation scheduling. Fan-aspirated shields are also important in the precise measurement
of air temperature and humidity gradients above the land surface.
Apogee Instruments model TS-100 fan-aspirated radiation shields are made from high-quality injection-molded
plastic with low thermal conductivity, maximum weather resistance, and a gloss white finish for high reflectivity.
The small size makes it easy to work with and reduces the surface area exposed to incoming radiation. The shield is
designed as a lightweight, low power, and low cost alternative to other fan-aspirated and naturally-aspirated
(passive) shields for air temperature and humidity measurements. The efficient, low-power fan draws ambient air
into the shield using a rocket nozzle contour to maximize airflow around the internal sensors. The curved inlet
helps draw air into the shield during high cross winds. These unique properties make the TS-100 ideal for use in
remote locations with limited power supply.
The TS-100 does not come packaged with any other sensors to accommodate users using other probes, however,
TS-100 shields are designed to optionally accommodate PRTs with a custom adapter. Apogee strongly
recommends using the ST-110, and recommends the TS-110 fan-aspirated radiation shield package, which comes
with a precision air temperature sensor (model ST-110, thermistor). ST-110 air temperature sensors are
weatherproof, have excellent long-term stability, and are designed for continuous air temperature measurement
when housed in the TS-100. ST-110 thermistors offer improved accuracy over thermocouples because they do not
require accurate measurement of datalogger panel temperature. The advantages of thermistors over platinum
resistance thermometers (PRTs) are high signal-to-noise ratio, requirement of only a single-ended channel for
measurement, and lower cost. Accelerated aging tests indicate that the epoxy-encased ST-110 thermistor has a
long-term stability equal to more expensive reference PRTs.
In 2019, Apogee added two additional sensor packages. The TS-120 package includes a TS-100 and an EE08 air
temperature/RH probe manufactured by E + E Elektronik in Austria. The version sold by Apogee Instruments
(Apogee model number EE08-SS) includes a M12 stainless steel connector and custom cable with a ninety degree
connector that optimizes the fit of the probe inside the Apogee TS-100 fan-aspirated radiation shield. The EE08-SS
offered by Apogee includes the proprietary coating from E + E Elektronik for the relative humidity sensing element
that provides maximum long-term stability. Additionally, the temperature and RH sensing elements are protected
by a stainless steel filter for maximum long-term stability. The TS-130 package includes a TS-100, EE08-SS, and ST-
110.
Measurement errors due to thermal conduction of heat to the sensor are minimized by reflective white heat shrink
tubing, and shading of lead wire on the north side of the shield (in the northern hemisphere; south side of shield in
southern hemisphere). Thermal conductivity to the precision thermistor is further minimized by using constantan
wire, which has twenty-fold lower thermal conductivity than copper wire.

SENSOR MODELS
TS-100 fan-aspirated radiation shields accommodate multiple air temperature and humidity sensors using sensor
port adapters. The following standard port adapter options are available (probes not included, the TS-110 includes
the ST-110 thermistor, the TS-120 includes the EE08-SS humidity probe, the TS-130 includes both the and EE08-SS
and ST-110):
Apogee Instruments model ST-110 (thermistor for air temperature)
Apogee Instruments model EE08-SS (probe for air temperature and humidity)
Apogee Instruments model ST-300 (PRT option for air temperature)
Campbell Scientific model CS215 (probe for air temperature and humidity)
Vaisala models HMP155, HMP110, and HMP60 (probes for air temperature and humidity)
Rotronic model HC2-S3* (probe for air temperature and humidity)
E + E models EE071 (probes for air temperature and humidity)
All sensor port adapters are capable of holding an ST-110 or ST-300 (user selected) air temperature sensor and a
temperature/humidity probe (if desired).
*If the Rotronic HC2-S3 probe is used with the E3 Active Set module, it must be water-proofed before use with the
Apogee TS-100 radiation shield. The E3 Active Set module is not water proof (water can infiltrate at the point
where the cable enters the housing). A small length of water-proof heat shrink (ATUM heat shrink) can be used to
seal the gasket where the cable enters the housing for the E3 Active Set. For more detail, contact technical support
at Apogee Instruments: mailto:[e-mail]
Temperature sensor model number and serial
number are located near the pigtail leads on the
sensor cable. If you need the manufacturing date
of your sensor, please contact Apogee Instruments
with the serial number of your sensor.
Fan-aspirated shield model and serial number are
printed on a white heat-shrink label located near
the pigtail leads on the fan cable. If you need the
manufacturing date of your sensor, please contact
Apogee Instruments with the serial number of your
sensor.
EE08-SS: Sensor model number and serial number are located on the probe
body between the connector and filter cap.

SPECIFICATIONS
TS-100/110/120/130
Radiation-induced Temperature Increase (RITI):
There is no reference standard for the elimination of radiation effects on air temperature measurement, but well-
designed fan-aspirated shields minimize this effect. In the absence of a standard, radiation-induced temperature
increase (RITI) was analyzed in long-term experiments over snow and grass surfaces by comparing temperature
measurements from nine replicate Apogee Instruments model TS-100 shields to measurements from two replicate
fan-aspirated shields from Met One (model 076B) and two replicate fan-aspirated shields from R. M. Young (model
43502). Comparisons among shields were made with ST-110 thermistors in all shields. In spite of careful placement
of shields away from each other and the tower (see photo below), and filtering for wind direction, these
experiments indicate that there is more variability among replicate shields (± 0.1 C) of the same model than
between models of shields (± 0.05 C), thus there is no statistical difference among the three models of shields.
Field tests indicate that low wind speed has a greater effect on RITI than high radiation load. For conditions of solar
radiation greater than 800 W m-2 and wind speeds less than 2 m s-1, the mean of the model TS-100 shields has
been within 0.05 C of the means of the other two models of shields. At higher wind speeds, the TS-100 and R. M.
Young shields read slightly cooler (-0.05 C) than the mean of the Met One shields, but the difference is not
statistically significant.

*IP55
The fan inside the TS-100 is extremely well sealed against water and dust, with an ingress protection (IP) rating of
55, called IP55. Higher numbers indicate better protection. Fans typically range from IP11 to IP55. The first digit in
the IP rating indicates protection against particle entry. A 5 indicates minimal dust entry with no interference with
fan operation. The second digit indicates water protection. A 5 indicates that water sprayed on the fan from any
direction shall have no harmful effects. Typical fans have particle and water protection ratings of 2 to 3, indicating
moderate particle and water protection, but no dust protection.
ST-110 (Precision Thermistor, not included w/ TS-100 or TS-120; included w/ TS-110 & TS-130)
TS-100/110/120/130
Difference among
Individual Replicate
Shields
Less than 0.1 C
Aspiration Rate
6 m s-1 at full-speed; 3 m s-1 at half-speed
Fan Input Voltage
Requirement
10.8 to 13.2 V DC
Fan Current Draw
80 mA at full-speed; 25 mA at half-speed
Fan Dust and Water
Protection
IP55*
Operating Temperature
-40 to 70 C
Dimensions
220 mm height, 270 mm diameter
Mass
840 g
Cables
5 m of shielded, twisted-pair wire for fan and air temperature sensors; TPR jacket (high water
resistance, high UV stability, flexibility in cold conditions); pigtail lead wires; stainless steel
(316), M8 connector located 25 cm from sensor head
ST-110
Measurement Range
-50 to 70 C
Measurement
Uncertainty
0.1 C (from 0 to 70 C); 0.15 C (from -35 to 0 C)
Measurement
Repeatability
less than 0.01 C
Non-stability
(Long-term Drift)
less than 0.02 C per year (when used in non-condensing environments where the annual
average temperature is less than 30 C; continuously high temperatures or continuously humid
environments increase drift rate)
Equilibration Time
5 s
Self-Heating
less than 0.01 C (typical, assuming pulsed excitation of 2.5 V DC); 0.08 C at 5 C (maximum,
assuming continuous input excitation of 2.5 V DC
Operating Environment
-50 to 70 C; 0 to 100 % relative humidity
Input Voltage
Requirement
2.5 V DC excitation (recommended, see (OPERATION AND MEASUREMENT section)
Output Voltage Range
0 to 2.5 VDC (assuming continuous input excitation of 2.5 V DC)
Current Drain
0.1 mA DC at 70 C (maximum, assuming continuous input excitation of 2.5 V DC)
Dimension
70 mm length; 2 mm diameter
Mass
60 g

EE08-SS (Air Temperature and Humidity Probe, not included w/ TS-100 or TS-110; included w/ TS-120 & TS-130)
EE08-Probe
Input Voltage
7 to 30 V DC
Current Draw
Less than 1.3 mA
Start-up Time
2 s
Housing
Polycarbonate, IP65
Filter
Stainless steel wire mesh, 30 micron pore size
Connector
M12, IP67
Dimensions
83 mm length, 12 mm diameter
Mass with 5 m Cable
270 g
Operating Environment
-40 to 80 C; 0 to 100 % relative humidity
Cable
M12 connector (IP67 rating) to interface to sensor housing, 5 m of four conductor, shielded,
twisted-pair wire (10 m and 20 m cables also available), white TPR jacket (high water
resistance, high UV stability, flexibility in cold conditions), pigtail lead wires
Warranty
1 year against defects in materials and workmanship
Temperature Measurement
Sensor
PT1000 (Class A)
Measurement Range
-40 to 80 C
Output Signal range
0 to 2.5 V DC
Accuracy at 20 C
± 0.2 C
Long-term Stability
Less than 0.1 C per year
Time Constant
Less than 30 s
Relative Humidity Measurement
Sensor
Capacitance Chip
Measurement Range
0 to 100 %
Output Signal Range
0 to 2.5 V DC
Accuracy at 20 C
± 2 % from 0 to 90 %; ± 3 % from 90 to 100 %
Temperature Response
Less than -0.05 % per C
Long-term Stability
Less than 1 % per year
Time Constant
Less than 30 s

DEPLOYMENT AND INSTALLATION
TS-100 fan-aspirated radiation shields come partially pre-assembled and has few parts, facilitating easy transport,
deployment, and maintenance.
Avoid placing the shield near buildings, paved surfaces, or any other locations which may create a micro-
environment significantly different than ambient environment. The World Meteorological Organization (WMO)
recommends a mounting height of 1.25 to 2 meters above ground. Air temperature typically decreases with
increasing height above the ground surface.
The shield is designed to hang from a standard IPS horizontal pipe
ranging from 1¼ inch (32 mm) to 2 inch (51 mm) in diameter. Attach
the hat to the pipe with the U-bolt, nuts, and rubber washers provided
(see diagram at left). Then, insert the shorter threaded end of the nylon
standoffs into the shield body. Once in place, align the other end of the
standoffs to the four corresponding holes in the hat and secure with
nylon nuts. Ensure that the sensor port (the hole in the side of the
shield where the air temperature and/or humidity probe mounts)
faces the nearest global pole (north for northern hemisphere, south
for southern hemisphere) to maximize shading of the lead wires.
When ordered with the TS-110, the ST-110 precision thermistor comes
fixed inside the desired sensor port adapter (an example is shown on
the next page). If not already installed, insert the adapter into the
sensor port (shown on next page) and rotate the adapter until it
matches the shield’s outer contour and will not come out when pulled. Look through the opening at the bottom of
the shield to verify that the thermistor tip is located concentrically in the middle of the airstream. If it is not,
remove the adapter and adjust the thermistor tip accordingly.
If desired, a humidity probe may be used with its accompanying sensor port adapter. If not pre-installed, slowly
insert the humidity probe into the adapter until the tip is in far enough to be centered in the air stream (about as
far as the included thermistor). If the o-rings bind or come lose, back out the probe, fix the o-ring positioning, and
retry. Rotating the humidity probe while inserting will help the o-rings stay in place. Additionally, the light use of a
lubricant, such as petroleum jelly, will greatly help humidity probe installation, and reduce risk of misplaced o-
rings. While installing the humidity probe, be sure not to put any unnecessary force on the neighboring pre-
installed thermistor cable; it has very thin internal wires which could easily break if handled incorrectly.
The underside of the hat has eight flat
surfaces where one or more included
cable tie mounts may affix. Using the
cable tie mounts is optional, but
provides an anchor to zip-tie cables to,
providing strain relief, extra shading of
cable, and a drip loop in the cable.

CABLE CONNECTORS
Apogee started offering in-line cable connectors on
some bare-lead sensors in March 2018 to simplify the
process of removing sensors from weather stations for
calibration (the entire cable does not have to be
removed from the station and shipped with the sensor).
The ruggedized M8 connectors are rated IP68, made of
corrosion-resistant marine-grade stainless-steel, and
designed for extended use in harsh environmental
conditions.
Inline cable connectors are installed 30 cm from the
head
(pyranometer pictured)
Instructions
Pins and Wiring Colors: All Apogee connectors have six
pins, but not all pins are used for every sensor. There
may also be unused wire colors inside the cable. To
simplify datalogger connection, we remove the unused
pigtail lead colors at the datalogger end of the cable.
If you ever need a replacement cable, please contact us
directly to ensure ordering the proper pigtail
configuration.
Alignment: When reconnecting your sensor, arrows on
the connector jacket and an aligning notch ensure
proper orientation.
Disconnection for extended periods: When
disconnecting the sensor for an extended period of time
from a station, protect the remaining half of the
connector still on the station from water and dirt with
electrical tape or other method.
A reference notch inside the connector ensures
proper alignment before tightening.
When sending sensors in for calibration, only send the
short end of the cable and half the connector.
Tightening: Connectors are designed to be firmly
finger-tightened only. There is an o-ring inside the
connector that can be overly compressed if a wrench is
used. Pay attention to thread alignment to avoid cross-
threading. When fully tightened, 1-2 threads may still
be visible.
Finger-tighten firmly

OPERATION AND MEASUREMENT
Connect the temperature sensor or RH probe sensor to a measurement device (meter, datalogger, controller). If
you are using the ST-110, this device must be capable of inputting 2.5 V DC, and measuring and displaying or
recording a millivolt (mV) signal (an input measurement range of 0-2500 mV is required to cover the entire
temperature range of the ST-110 air temperature sensor). In order to maximize measurement resolution and
signal-to-noise ratio, the input range of the measurement device should closely match the output range of the
sensor.
Connect the fan to a 12 V DC power supply capable of supplying at least 80 mA. If the datalogger has the capability
for pulse width modulation (PWM) it can be used to reduce fan speed at night or under conditions of low solar
radiation and/or high wind speed. The datalogger or controller must have a pulse width modulation (PWM) output
of approximately 20 kHz and a duty cycle of 50 to 100 %.
The tachometer output is measured by a pulse counter. The tachometer also requires an input voltage, where
maximum voltage output to the pulse counter is the input voltage to the counter. The tachometer output allows
monitoring of the fan to ensure it is functioning properly.
The following instructions are for the ST-110 thermistor included with the TS-110 option. For wiring other sensors,
including PRT sensors, please see their respective manuals.
VERY IMPORTANT: Apogee changed all wiring colors of our bare-lead sensors in March 2018. To ensure
proper connection to your data device, please note your serial number or if your sensor has a stainless-steel
connector 30 cm from the sensor head then use the appropriate wiring configuration below.
Wiring for ST-110 Serial Numbers range 0-2724
Plug each wire into the appropriate data logger terminal following the illustrations below:
Thermistor
Measurement devices (e.g., datalogger, controller) do not measure resistance directly, but determine resistance
from a half-bridge measurement, where an excitation voltage is input across the thermistor and an output voltage
is measured across the bridge resistor.
Red: Excitation Channel (excitation for
thermistor)
Black: Single-ended channel (positive
thermistor lead)
Blue: Analog Ground (negative thermistor
lead)
Clear: Ground (shield wire)

Wiring for ST-110 Serial Numbers 2725 and above
An excitation voltage of 2.5 V DC is recommended to minimize self-heating and current drain, while still
maintaining adequate measurement sensitivity (mV output from thermistor per C). However, other excitation
voltages can be used. Decreasing the excitation voltage will decrease self-heating and current drain, but will also
decrease thermistor measurement sensitivity. Increasing the excitation voltage will increase thermistor
measurement sensitivity, but will also increase self-heating and current drain.
Wiring for EE08-SS
*For more information, please see the EE08-SS manual:
Red: Input voltage (7 to 30 V DC)
Black: Ground
Green: Single-ended channel (signal output by
air temperature sensor)
Clear: Ground (shield)
White: Single-ended channel (signal output by
relative humidity sensor)
Red: Excitation channel (excitation for
thermistor)
White: Single-ended channel (positive thermistor
lead)
Black: Ground (negative thermistor lead)
Clear: Shield/Ground

Conversion of Thermistor Resistance to Temperature
The thermistor is a resistive element, where resistance changes with temperature. Thermistor resistance (RT, in Ω)
is measured with a half-bridge measurement, requiring a known excitation voltage input (VEX) and a measurement
of output voltage (VOUT):







 1
V
V
24900R
OUT
EX
T
(1)
where 24900 is the resistance of the bridge resistor in Ω. From resistance, temperature (TK, in Kelvin) is calculated
with the Steinhart-Hart equation and thermistor specific coefficients:
3
TT
K))R(ln(C)Rln(BA 1
T 
(2)
where A = 1.129241 x 10-3, B = 2.341077 x 10-4, and C = 8.775468 x 10-8 (Steinhart-Hart coefficients). If desired,
measured temperature in Kelvin can be converted to Celsius (TC):
15.273TT KC 
. (3)
Fan Operation
Under some environmental conditions (e.g., high wind speed, low solar radiation), accurate measurements can be
made without running the fan at full speed. Fan speed and power consumption can be decreased using a pulse
width modulation (PWM) signal. The PWM signal should have a frequency of approximately 20 kHz and a duty
cycle of 50 to 100 %, where a duty cycle of 100 % is full power and 50 % is low power. Running the fan in a low
power mode reduces the current draw from 80 mA to approximately 25 mA. The only way to completely stop the
fan is to turn the power off.
Red: 12 V DC (positive fan lead)
Black: Analog Ground (negative fan lead)
Clear: Analog Ground
Green: Control port (controls fan speed using pulse width
modulation)
Blue: Voltage Source (power input for tachometer; must be less
than 30 V)
White: Pulse Counter or Control Port (tachometer output)

The fan also has a tachometer to monitor blade revolutions per minute (RPM). The tachometer outputs a pulse
voltage signal. The pulse multiplied by 30 yields fan RPMs. The RPM should be near 4500 in full power mode and
2500 in low power mode. In addition to the tachometer output wire, there is a pull-up wire (power input). This
allows a user-defined maximum output voltage from the tachometer, and facilitates interfacing with multiple
measurement devices.

MAINTENANCE AND RECALIBRATION
At full duty, the fan is designed to last 50,000 hours (5.7 years). Ultimately, this depends on operating conditions,
and actual results may vary. If the fan runs less than approximately 4500 RPM at full power, then there may be a
blockage or the fan may need to be replaced. The fan is secured by four nylon screws and can be easily removed.
When a replacement fan is installed, verify that it is oriented the correct way, with air being pulled upwards
through the shield towards the hat. Ensure that the replacement fan is wired correctly as outlined in the
OPERATION AND MEASUREMENT section.
Inspect the shield regularly and clean as needed to maintain optimum performance. If the shield or hat is dirty,
wipe the surface with a moist rag to remove buildup and return the surface to its original condition. Check all
mounting nuts and tighten if they are loose.
For optimal accuracy, check the yellow-bead thermistor every three months for dust/dirt buildup. If needed, twist
and pull out the sensor port adapter, then wipe the thermistor tip clean. Be sure to return the thermistor to its
proper position as outlined in the DEPLOYMENT AND INSTALLATION section.
Apogee ST-110 temperature sensors are factory verified to ensure accuracy. Sensors are compared for absolute
temperature against the mean of two reference PRTs in a constant temperature bath, over a range of
approximately -35 to 60 C.
EE08 probes are rugged and weatherproof and designed for air temperature and relative humidity measurements
inside radiation shields. When probes are not in use, it is recommended they be removed from the measurement
environment, cleaned, and stored. EE08 probes, especially the filter cap, should be periodically cleaned to remove
all dust and debris. Additional filter caps are available from Apogee to replace clogged filter caps. For more
information about filter cap replacement, call or email Apogee technical support: 435.245.8012,
[e-mail].
EE08 probes are factory calibrated and preprogrammed and come with a generic calibration factor (see Sensor
Calibration in OPERATION AND MEASUREMENT section). A custom calibration can be derived by comparing the air
temperature or relative humidity measurements from the probe to reference air temperature or relative humidity
measurements. Probes can also be recalibrated at the factory. Recalibration is recommended every two years.
Recalibration information is found on the Apogee webpage: https://www.apogeeinstruments.com/recalibration-
and-repairs/. Questions about recalibration can be emailed to: [e-mail].

TROUBLESHOOTING AND CUSTOMER SUPPORT
Independent Verification of Functionality
Apogee ST-110 temperature sensors yield a resistance proportional to temperature. A quick and easy check of
sensor functionality can be accomplished with an ohmmeter. Connect the lead wires of the ohmmeter to the red
and white wires from the sensor. The resistance should read 10 kΩ (10,000 ohms) at 25 C. If the sensor
temperature is less than 25 C, the resistance will be higher. If the sensor temperature is greater than 25 C, the
resistance will be lower. Connect the lead wires of the ohmmeter to the white and black wires from the sensor.
The resistance should read 24.9 kΩ, and should not vary. Connect the lead wires of the ohmmeter to the red and
black wires from the sensor. The resistance should be the sum of the resistances measured across the red and
white wires, and white and black wires (e.g., 10 kΩ plus 24.9 kΩ at 25 C).
A quick and easy check of fan functionality can be determined using a DC power supply. Power the fan with 12 V
DC by connecting the positive voltage signal to the red wire from the fan and the negative (or common) to the
black wire from the fan. When powered, the fan blades should spin. Make sure to keep fingers clear of blades
before connecting fan to 12 V DC.
EE08 probes output voltage signals linearly proportional to air temperature and relative humidity. A quick and easy
check of probe functionality can be accomplished with a voltmeter and 9 V battery. Connect the red wire from the
probe to the positive terminal on the 9 V battery, and connect the black wire from the probe to the negative
terminal on the 9 V battery. Connect the positive lead wire of the voltmeter to the green wire from the probe and
the negative lead wire of the voltmeter to the black wire from the probe. The voltage measurement should be 1.25
V DC at 20 C and 1.350 V DC at 25 C (20 to 25 C is the approximate room temperature range). Move the positive
lead wire of the voltmeter to the white wire from the probe. The voltage measurement should be 0.5 V DC at 20 %,
1.25 V DC at 50 %, and 2.0 V DC at 80 %.
Compatible Measurement Devices (Dataloggers/Controllers/Meters)
Measurement of ST-110 thermistor resistance requires an input excitation voltage, where 2.5 V DC is
recommended. A compatible measurement device should have the capability to supply the necessary voltage for
the specific sensor.
The sensitivity (mV output from thermistor per C) of the temperature measurement from the ST-110 thermistor
varies with the excitation voltage, and varies as a function of temperature. With an excitation voltage of 2.5 V DC,
the sensitivity is lowest near the ends of the measurement range, -50 and 70 C. A compatible measurement device
(e.g., datalogger or controller) should have resolution of at least 0.6 mV, in order to produce temperature
resolution of less than 0.1 C across the entire temperature measurement range (less than 0.05 C from -35 to 45 C).
To operate the fan, a 12 V DC power supply capable of supplying at least 80 mA is required. All fans also include
pulse width modulation (PWM; allows for reduction of fan speed under certain conditions) and a tachometer
(allows for monitoring of fan speed). In order to use the PWM option, the fan must be connected to a datalogger
or controller that has a PWM output of approximately 20 kHz, a duty cycle of 50 to 100 %, and a 0 to 5 V DC square
waveform. To measure the output from the tachometer, a pulse counter is required. The maximum voltage input
from the tachometer to the pulse counter is determined by the input voltage to the tachometer, which should be
fixed at a given voltage in the range of 0 to 30 V DC. The measurement device should be capable of supplying a
fixed voltage in this range.
An example datalogger program for Campbell Scientific dataloggers can be found on the Apogee webpage at
http://www.apogeeinstruments.com/content/Aspirated-Radiation-Shield-Thermistor.cr1.

Operation of the EE08 requires a voltage input of 7 to 30 V DC. Measurement of the output signals requires a
single-ended voltage measurement over a range of 0 to 2.5 V DC. A compatible measurement device should have
the capability to supply and measure these voltages.
The sensitivity of the air temperature sensor (voltage output from sensor per degree C) is 20.8 mV per C (reciprocal
of the slop listed in the OPERATION AND MEASUREMENT section). This means a voltage measurement resolution
of 2.08 mV is required to yield an air temperature measurement resolution of 0.1 C, and 0.208 mV is required to
yield an air temperature measurement resolution of 0.01 C. The sensitivity of the relative humidity sensor (voltage
output from sensor per % RH) is 25 mV per % (reciprocal of the slope listed in the OPERATION AND
MEASUREMENT section). This means a voltage measurement resolution of 2.5 mV is required to yield a relative
humidity measurement resolution of 0.1 % C, and 0.25 mV is required to yield a relative humidity measurement
resolution of 0.01 %.
An example datalogger program for Campbell Scientific dataloggers can be found on the Apogee webpage at:
https://www.apogeeinstruments.com/content/EplusE-EE08-Temp-RH-Probe.CR1
Effect of Cable Length & Modifying Cable Length
When the temperature sensor is connected to a measurement device with high input impedance, sensor output
signals are not changed by shortening the cable or splicing on additional cable in the field. Tests have shown that if
the input impedance of the measurements device is 1 mega-ohm or higher then there is negligible effect on the
sensors, even after adding up to 100 m of cable. TS-100 aspirated radiation shields use shielded, twisted pair cable,
which minimizes electromagnetic interference. This is particularly important for long lead lengths in
electromagnetically noisy environments.
Standard Apogee cable lengths for the EE08 are 5 m, 10 m, and 20 m. If a length greater than 20 m is required,
additional cable can be spliced onto a standard cable. For cable extensions, shielded, twisted-pair cable is
recommended, in order to minimize electromagnetic interference. This is particularly important for long lead
lengths in electromagnetically noisy environments. However, additional cable adds resistance and may influence
the accuracy of the measurement.
See Apogee webpage for details on how to extend sensor cable length (http://www.apogeeinstruments.com/how-
to-make-a-weatherproof-cable-splice/).

RETURN AND WARRANTY POLICY
RETURN POLICY
Apogee Instruments will accept returns within 30 days of purchase as long as the product is in new condition (to be
determined by Apogee). Returns are subject to a 10 % restocking fee.
WARRANTY POLICY
What is Covered
All products manufactured by Apogee Instruments are warranted to be free from defects in materials and
craftsmanship for a period of four (4) years from the date of shipment from our factory. To be considered for
warranty coverage an item must be evaluated either at our factory or by an authorized distributor.
Products not manufactured by Apogee (spectroradiometers, chlorophyll content meters, EE08-SS air
temperature/relative humidity probes) are covered for a period of one (1) year.
What is Not Covered
The customer is responsible for all costs associated with the removal, reinstallation, and shipping of suspected
warranty items to our factory.
The warranty does not cover equipment that has been damaged due to the following conditions:
1. Improper installation or abuse.
2. Operation of the instrument outside of its specified operating range.
3. Natural occurrences such as lightning, fire, etc.
4. Unauthorized modification.
5. Improper or unauthorized repair.
Please note that nominal accuracy drift is normal over time. Routine recalibration of sensors/meters is considered
part of proper maintenance and is not covered under warranty.
Who is Covered
This warranty covers the original purchaser of the product or other party who may own it during the warranty
period.
What We Will Do
At no charge we will:
1. Either repair or replace (at our discretion) the item under warranty.
2. Ship the item back to the customer by the carrier of our choice.
Different or expedited shipping methods will be at the customer’s expense.

How To Return An Item
1. Please do not send any products back to Apogee Instruments until you have received a Return Merchandise
Authorization (RMA) number from our technical support department by calling [phone] or by submitting an
online RMA form at www.apogeeinstruments.com/tech-support-recalibration-repairs/. We will use your RMA
number for tracking of the service item.
2. Send all RMA sensors and meters back in the following condition: Clean the sensor’s exterior and cord. Do not
modify the sensors or wires, including splicing, cutting wire leads, etc. If a connector has been attached to the
cable end, please include the mating connector –otherwise the sensor connector will be removed in order to
complete the repair/recalibration.
3. Please write the RMA number on the outside of the shipping container.
4. Return the item with freight pre-paid and fully insured to our factory address shown below. We are not
responsible for any costs associated with the transportation of products across international borders.
5. Upon receipt, Apogee Instruments will determine the cause of failure. If the product is found to be defective in
terms of operation to the published specifications due to a failure of product materials or craftsmanship, Apogee
Instruments will repair or replace the items free of charge. If it is determined that your product is not covered
under warranty, you will be informed and given an estimated repair/replacement cost.
Apogee Instruments, Inc.
721 West 1800 North Logan, UT
84321, USA
OTHER TERMS
The available remedy of defects under this warranty is for the repair or replacement of the original product, and
Apogee Instruments is not responsible for any direct, indirect, incidental, or consequential damages, including but
not limited to loss of income, loss of revenue, loss of profit, loss of wages, loss of time, loss of sales, accruement of
debts or expenses, injury to personal property, or injury to any person or any other type of damage or loss.
This limited warranty and any disputes arising out of or in connection with this limited warranty ("Disputes") shall
be governed by the laws of the State of Utah, USA, excluding conflicts of law principles and excluding the
Convention for the International Sale of Goods. The courts located in the State of Utah, USA, shall have exclusive
jurisdiction over any Disputes.
This limited warranty gives you specific legal rights, and you may also have other rights, which vary from state to
state and jurisdiction to jurisdiction, and which shall not be affected by this limited warranty. This warranty
extends only to you and cannot by transferred or assigned. If any provision of this limited warranty is unlawful,
void or unenforceable, that provision shall be deemed severable and shall not affect any remaining provisions. In
case of any inconsistency between the English and other versions of this limited warranty, the English version shall
prevail.
This warranty cannot be changed, assumed, or amended by any other person or agreement.
APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
TEL: [phone] | FAX: [phone] | WEB: APOGEEINSTRUMENTS.COM
Copyright © 2019 Apogee Instruments, Inc.