FiberMASTER side
21
Measuring Cabling Loss
Loss measurements are performed to certify a cabling link meets certain
criteria for attenuation. Loss (dB) can be manually calculated by subtracting
the power (dBm) through the cabling under test from the power (dBm) of the
light source when connected directly to the meter. To make this process easier
FiberMASTER includes a calibration function that stores the light source power
level and compares it to future readings and directly displays loss in dB on the
LCD panel.
1. With the dust cap on the power meter, press the power
button. The meter will display ‘null’, indicating that it is ready to
measure and is currently receiving no power. Press the
wavelength ‘
λ
’ button to change to the desired wavelength.
Select 850nm if using the IDEAL #33-926 light source.
2. Remove the dust cap and connect the reference jumpers between the power meter
and light source. The meter will display the current power dBm from the light source.
3. Press the ‘dB/Cal’ button on the power meter to store the current value into memory.
The display will now indicate 0.00dB.
4. Remove the coupler from the two reference jumpers, connect to the cabling under test
and begin making measurements. The display will indicate the attenuation (dB) compared
to the initial calibration power (dBm).
See diagrams on the following page.
Do not disconnect the reference jumper from the light source after calibrating the test set.
Doing so will cause inaccuracies and requires recalibration.
Calibration Procedure Diagrams
The following diagrams supplement steps 1-4 on the
previous page.
Step 1
Affix the black dust cap to the input of the power meter.
Clear dust caps allow ambient light to pass and cannot be
used. Turn on the power meter and wait for ‘null’ to be
displayed on the
LCD. The meter is now ready to use.
