Extech Instruments LT300 User manual
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Warranty
EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects
in parts and workmanship for one year from date of shipment (a six month limited warranty
applies to sensors and cables). If it should become necessary to return the instrument for
service during or beyond the warranty period, contact the Customer Service Department at
(781) 890-7440 ext. 210 for authorization or visit our website www.extech.com for contact
information. A Return Authorization (RA) number must be issued before any product is
returned to Extech. The sender is responsible for shipping charges, freight, insurance and
proper packaging to prevent damage in transit. This warranty does not apply to defects
resulting from action of the user such as misuse, improper wiring, operation outside of
specification, improper maintenance or repair, or unauthorized modification. Extech
specifically disclaims any implied warranties or merchantability or fitness for a specific
purpose and will not be liable for any direct, indirect, incidental or consequential damages.
Extech's total liability is limited to repair or replacement of the product. The warranty set
forth above is inclusive and no other warranty, whether written or oral, is expressed or
implied.
Introduction
Congratulations on your purchase of the Extech LT300 Digital Light Meter. The LT300
measures light level (illuminance) to 200,000 Lux (20,000 Fc). The LT300 offers a backlit
display, MAX/MIN, Data Hold, Relative, Peak, and Reset features. This instrument is
shipped fully tested and calibrated and, with proper use, will provide years of reliable
service.
Meter Description
1. Sensor cable
2. Analog bargraph
3. Numerical display
4. RANGE button
5. ON/OFF button
6. MAX/MIN button
7. RESET button
8. LCD Backlight button
9. LUX button
10. Fc foot candle button
11. Protective rubber jacket
12. RELATIVE button
13. Data HOLD button
14. PEAK button
15. Photo sensor dome
Notes: Protective sensor cap not shown. Battery compartment, Tilt Stand, and Tripod Mount arelocated on the rear
of the instrument. The protective rubber jacket must be removed frommeter to access battery compartment.
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Operation
Light sensor
1. The light sensor is permanently
attached to the meter by the coiled
cable.
2. Remove the protective cap by
unsnapping it to expose the white
domed light sensor. When the sensor’s protective cap is removed, the white domed
light sensor lens will begin to capture light. Replace the cap when the meter is not in
use.
Turn Power ON or OFF
Press the button to turn power on or off. If the display does not switch on, check that
the 9V battery is installed and is fresh.
Selecting Lux or Foot candle units of measure
Press the LUX button to select lux units or the Fc button to select foot candle units.
Measurement Procedure
1. Remove the protective cap from the sensor so that the white domed light sensor is
exposed to the light. For overhead lighting, the sensor can be placed on a desk or
table top. A tripod mount and a tilt stand are located on the rear of the meter for
convenience.
2. The display will indicate the light level in Fc or Lux.
3. Press the RANGE button to select the range that provides the maximum resolution. If
the ‘OL’ appears the light measurement is out of range. Select another range using the
RANGE button.
4. Press the backlight button to illuminate the LCD display if needed.
MAX/MIN
The Max/Min function allows for recording and display of the maximum and minimum light
levels over time.
1. Press the MAX/MIN button. The MAX display icon will appear and meter will now
display and hold only the highest reading. The display will update only when a higher
reading is measured.
2. Press MAX/MIN button. The MIN display icon will appear and meter will now display
and hold only the lowest reading. The display will update only when a lower reading is
measured
3. Press MAX/MIN again. The MAX MIN display icons will appear flashing and meter will
now display the current reading, but will continue to record the highest and lowest
values.
4. Press MAX/MIN again to cycle through MAX and MIN displays.
5. To exit the MAX MIN mode, press and hold the MAX/MIN button until the MAX and
MIN icons completely disappear.
Data Hold
Press the HOLD button to freeze the displayed reading. The ” MANU HOLD” hold icon will
appear on the display. Press the HOLD button again to return to normal operation. When
the Data Hold function is enabled the analog bar graph will continue to display level
changes.
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Peak Hold
The Peak Hold feature allows the meter to captures light pulses that rise or fall down to
10µs.
1. Press and hold the PEAK button until CAL appears in the display.
2. Momentarily press the PEAK button. The ‘PMAX’ icon will appear on the LCD. The
meter will then measure and display any light pulses. The display will hold the results
until a higher pulse appears.
3. Press the PEAK button again to display the “PMIN” values.
4. To exit the Peak Hold mode, press and hold the PEAK button until the ‘PMAX’ or ‘PMIN’
icon disappears.
Relative mode
Measurements can be displayed as a difference between the measured light level and a
stored reference value. To store a reading as a reference, press the REL button when the
desired reference measurement is on the LCD (the REL icon will switch on). All
subsequent displayed readings will be “relative” to the stored reference value. For
example, if the reference value is 100 and the actual light level is 125, the meter will
display 25. To view the reference value, press the REL button again so that the REL icon
begins to flash. The displayed value will be the reference value. To exit the Relative mode,
press and hold the REL button until the REL icon disappears.
RESET
Press the RESET button to clear the memory and exit from REL, HOLD, PEAK and
MAX/MIN. The RESET will also reset the auto power off timer.
Backlight
Press the “ “ button to turn the backlight on. Press again to turn it off.
Maintenance
Cleaning and storage
1. The white plastic sensor dome should be cleaned with a damp cloth when necessary.
Use only a mild soap if needed. Do not use solvents, abrasives, or harsh detergents to
clean the dome.
2. Store the meter in an area with moderate temperature and humidity (refer to the
operating and storage range in the ‘Specifications’ section).
Battery Replacement
When the battery power begins to fail the low battery symbol “ ”will appear on the LCD.
Replace the 9V battery by first removing protective jacket that encases the meter. Remove
the rear (center) battery compartment screw to access the battery compartment. Ensure
that the compartment cover is securely fastened and that the protective jacket is properly
installed before using the meter.
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Support line (781) 890-7440
Technical support: Extension 200; E-mail: support@extech.com
Product specifications subject to change without notice
For the latest version of this User’s Guide, Software updates, and other
up-to-the-minute product information, visit our website: www.extech.com
Extech Instruments Corporation, 285 Bear Hill Rd., Waltham, MA 02451
Specifications
Ranges and Resolution Accuracy
Lux
40.00, 400.0, 4000, 40.00k, 200.0kLux ± (5% Rdg + 0.5% Full Scale)
Foot candle (Fc)
40.00, 400.0, 4000, 20.00kFc ± (5% Rdg + 0.5% Full Scale)
General Specifications
Display Multi-function 3-3/4 (3999) digit LCD with Bargraph indicator
Over range indication LCD displays ‘OL’
Spectral response CIE photopic (CIE human eye response curve)
Spectral accuracy CIE Vfunction (f1 ï 6%)
Measurement Repeatability±2%
Temperature coefficient ±0.1% per oC
Sampling rate 13.3 times per second (bargraph); 1.3 times per second (digital
display)
Photo detector Silicon photo-diode with spectral response filter
Peak Hold Capture light peaks to 10µS
Operating conditions Temperature: 32 to 104oF (0 to 40oC); Humidity: < 80% RH
Storage conditions Temperature: 14 to 140oF (-10 to 50oC); Humidity: < 80% RH
Dimensions 6.5 x 3.0 x 1.7" (165 x 76 x 43mm)
Weight Approx. 14.2 oz. (403g) with battery installed
Low battery indication “ ” appears on the LCD
Power supply 9V battery
Calibration and Repair Services
Extech offers repair and calibration services for the products we sell. Extech also
provides NIST certification for most products. Call the Customer Service Department for
information on calibration services available for this product. Extech recommends that
annual calibrations be performed to verify meter performance and accuracy.
Copyright ©2006 Extech Instruments Corporation.
All rights reserved including the right of reproduction in whole or in part in any form.
Appendix
Typical Light Levels
Lux Foot
Candles
Lux Foot
Candles
Factories Home
20-75 2-7 Emergency Stairs, Warehouse 100-150 10-15 Washing
75-150 7-15 Exit/Entrance Passages 150-200 15-20 Recreational
Activities
150-300 15-30 Packing Work 200-300 20-30 Drawing Room,
Table
300-750 30-75 Visual Work: Production Line 300-500 30-50 Makeup
750-1,500 75-150 Typesetting: Inspection Work 500-1,500 50-150 Reading, Study
1,500-3,000 150-300 Electronic Assembly, Drafting 1,000-2,000 100-200 Sewing
OceRestaurant
75-100 7-10 Indoor Emergency Stairs 75-150 7-15 Corridor Stairs
100-200 10-20 Corridor Stairs 150-300 15-30 Entrance,
Wash Room
200-750 20-75 Conference,
Reception Room
300-750 30-75 Cooking Room,
Dining Table
750-1,500 75-150 Clerical Work 750-1,500 75-150 Show Window
1,500-2,000 150-2000 Typing, Drafting
Store Hospital
75-150 7-15 Indoors 30-75 3-7 Emergency Stairs
150-200 15-20 Corridor/Stairs 75-100 7-10 Stairs
200-300 20-30 Reception 100-150 10-15 Sick Room,
Warehouse
300-500 30-50 Display Stand 150-200 15-20 Waiting Room
500-750 50-75 Elevator 200-750 20-75 Medical Exam
Room
750-1,500 75-150 Show Window,
Packing Table
750-1,500 75-150 Operating Room
1,500-3,000 150-300 Storefront, Show Window 5,000-10,000500-1000 Eye Inspection
Spectral Sensitivity
400 450 500 550 600 650 700
Wavelength (nm)
- - - - - Light Meter Response _____ CIE Response
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more info for Extech LT300
Phone: 01235 838 555
Email: cs@airconcern.co.uk
Web: www.airconcern.co.uk
Air Concern Ltd, Building 173 Curie Avenue Harwell Didcot, Oxfordshire
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