SEFRAM 7940 Series User manual

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SEFRAM 7940
Optical Power Meter

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Content
1. Overview………………………………….……….…………03
2. Specifications………………………...…………………….03
3. Standard Packages…………………….…………………..04
4. Components Guide………………...……………………...05
5. Operation and Notes………………...…………………….06
6. Maintenance…………...……………..…………………….09
7. Troubleshooting……………………………………….…..10
8. Changing battery…………………………………….…….10
9. Warranty and Servicing…………………………….…….11
…………………………………………………………………………………………
The information contained in this document is assumed to be correct
and current. The manufacturer is not responsible for errors of
omissions and reserves the right to change specifications at any
time without notice.
M 7940A 00 / 08-2011

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1. Overview
SEFRAM has designed the SEFRAM 7940 series optical power meter to meet
the high demand. It can be used for the absolute power measurement and
relative measurement of the link loss in dB. Its compact size, friendly
operation interface, broad power measurement range, high precision and
brand-new user automatic calibration function and high performance in
application makes it an ideal tool for optical fiber network.
SEFRAM 7940 Specifications:
Wavelength: 850nm, 980nm, 1300nm, 1310 nm, 1490nm, 1550nm
Measurement Range: -50 to +26dBm
2. Specifications
Model
SEFRAM 7940
Wavelength Range（nm）*1
800~1600
Detector Type
InGaAs
MeasurementRange（dBm）*2
-50~+26
Uncertainty*3
±0.15dB
Accuracy
Linear 0.1% or Nonlinear 0.01dBm
Operating Temperature（°C）
-10 to +60°C
Storage Temperature（°C）
-25 to+70°C
Auto-off Time（min）
10
Operating Time（h）
≥130
Battery
3 AA1.5V
Weight（g）
200
Dimensions（mm）
152X74X26

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Notes:
1. Wavelength Range: Specified standard operating wavelength range in
which the Power Meter can work properly under certain technical
specifications.
2. Power Measurement Range: The maximum and minimum range in which
the Power Meter can work properly.
3. Uncertainty: Difference between two measurement results that were tested
by Power Meter and another Standard Power Meter respectively.
3. Standard packages
1. SEFRAM 7940 Handheld Power Meter……………….. 1
2. Manual………………………………………………….… 1
3. Protective Holster………………………………………… 1
4. 1.5V AA Battery………………………………………….... 3
5. Cotton Swabs…………………………………………….. 1

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4. Components Guide
(1) LCD: The LCD screen display the measurement tested in dB, dBm,
mW, uW, nW unit; the selected wavelength; the current operating situation
and so on.
(2) ON/OFF Key: Press the key to turn the unit on/off.
(3) dB Key: To test the power value under certain wavelength.
(4) ZERO Key: Press the key for auto-zero.
(5) “λ” Key: To switch the current operating wavelength between
850nm、980nm、1300nm、1310nm、1550nm.
(6) LIGHT Key: To turn the background light on/off.
(1) LCD
(3) dB
(6) Backlight
(5) λ
(2) ON/OFF
(1) LCD
(4) Zero
(7) HOLD

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5. Operation and Notes
5.1 ON/OFF
(1) Press the On/Off key for a few seconds to turn on the unit
(2) Press the On/Off key for a few seconds to turn off the unit
5.2 Absolute power measurement
(1) Turn on the Power Meter
(2) Press the λ key to switch between the wavelengths. The default
wavelength is 1310nm.
(3) Connect the light to be measured, and then reading will be
displayed on the LCD screen, including Linear and nonlinear
value.
5.3 Relative power measurement.
(1) Select the wavelength to be measured.
(2) Under “Absolute power measurement mode”, connect to the
light to be tested.
(3) Press dB key, then current power value is stored as a
reference value in dB unit. At the same time it also display
the current absolute power value and current relative value is
0dB.
(4) Connect to another beam of light to be tested, display the
current relative power value and absolute power value under
tested.
5.4 Special function
SEFRAM 7940 has 3 kinds of working mode: (1) Factory Mode
(2) User Mode
(3) Working Mode

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5.4.1 Factory Mode: The factory is responsible for the test and calibration
5.4.2 User Mode: Press the λ + Light key synchronously, and then enter the
User mode. A sign "T" will be displayed at the left side of the display. Press
theλ + Light key synchronously once again, it exit from the User mode and
enter the Working mode. (the T sign will disappear).
Function
Button
―――
Plus 0.05
Light
―――
Minus 0.05
dB
―――
Store
Zero
―――
Switch Wavelength
λ
―――
Return to the Factory
Setting
λ+ Zero
―――
Notes: If any errors or mistakes caused by the user self-calibration operation,
please press theλ+ Zero synchronously under the user mode to go back to the
factory setting.
(1) Auto-off : Press LIGHT + dB key to turn on the auto-off function. The
auto-off symbol will be displayed on the top right. The unit will be turn off
automatically after 10 minutes idle time.
(2) Background light On/Off: Under the Working Mode, press LIGHT to turn
the background light On/Off. A little sun symbol will be displayed on the
top right.

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Appendix:
Optical fiber loss measurement
Step 1- Optical Reference Level
Turn on optical power meter and press the λ key to select the wavelength.
Turn on optical light source (emitting source) and select the wavelength.
Wait for 1-2 minutes until it stabilize.
Select a piece of patch cords, which is used to connect with the light
source, we call it emitting patch cords. Cleaning connector of the patch
cords. The fiber of the emitting source patch cords must be the same fiber
type as the fiber under test.
Connect the light source (emitting source) with the 7940 through the
emitting source patch cords
SEFRAM 7940 get the power measurement value. This value should be
close to the one that light source (emitting source) set. If it has wide
disparity, please make sure the fiber connection is clean properly else
replace another jumpers.
Press the dB key; the reading 0.00dB will be displayed on the screen. The
tested power values will be set to the reference value.
Step 2-Optical Loss Measurement
Keep the emitting source patch cords connection with the light source
(emitting source).
Connect the 7940 and light source (emitting source) to the optical fiber
link respectively.
Notes: cleaning all the connectors surface including all the necessary optical
adaptors. The reading in dB unit displayed on the screen is the tested optical
fiber link loss.(also display the current absolute optical power value in dBm
unit).

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6. Maintenance
1. It is important to keep all optical connectors and surfaces free from oil,
dirt or other contamination to ensure proper operation.
2. Keep using one type of adapter to avoid excess loss from different
connectors.
3. Please use dust proof cap for protection to avoid begin scratched or
contaminated when SEFRAM 7940 not in operation.
4. Light interface is sensitive, please carefully plug in and pull out the
connectors.
5. Please use clean cotton to clean the sensor surface, clean it in
clockwise direction carefully.
6. If does not need to use for a long time, please take out the battery.

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7. Trouble shooting
Description
Problem
Method
Faint LCD display
Battery is weak
Change battery
No display after
turning on the unit
Battery is
weak/Others
Turn on the unit
again/Change battery
Insensitive display in
LCD
Light interface is
polluted/
broken/Display
locked
Check connector
carefully and clean
sensor’s interface
8. Change Battery
8.1 If you find battery is weak while operating it, please immediately turn
the unit off and change a new battery.

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9．Warranty and Servicing
In case of failure or problem, please contact SEFRAM after sales department
to send back your instrument.
9.1 2 years Warranty for SEFRAM 7940 Handheld Power Meter
SEFRAM warrants that every Handheld Power Meter 7940 will be free from
defects in material and workmanship for a period of 24 months. This warranty
covers the original user only and is not transferable. Should the device fail at
any time during this warranty period, We will, at its sole discretion, replace,
repair or refund the purchase price of the product.
This warranty is limited to defects in workmanship and materials and does not
cover damage from accident, acts of God, neglect, contamination, misuse or
abnormal conditions of operation or handling.
To establish if the product is covered by the warranty please provides date of
purchase and delivery note to SEFRAM with the defect power meter. This
warranty will not go into effect until we have received the delivery note as a
proof of warranty with the power meter returned to our after sales department.
Failure to properly protect the product during shipping may avoid this
warranty.

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SEFRAM
32, rue Edouard MARTEL
BP 55
F42009 SAINT-ETIENNE Cedex 2
Tel : [phone]
Fax : [phone]
Mail : [email protected]
Web : www.sefram.fr