– 13 –
7.
Turn the test set off by pressing the “ON/OFF” switch and remove
only the cable
attached to the “DETECTOR” receptacle. If you are using an external source,
turn it off to ensure eye safety during the next steps.
8.
For the plastic fi ber, measure a distance of fi ve meters (5 m) from the unconnected
end of the cable, then cut it squarely with a single edge razor or a tool such as the
IF-FC1. If the original cable end had an ST
®
connector, complete the termination
process by following the installation instructions for a new connector. Regardless
of the cable type it is important to restore the same condition as the original cable
end to reduce the effect of the cut on the measurement.
9.
Insert the newly terminated cable end into the “DETECTOR” receptacle. Turn
the test set on by pressing the “ON/OFF” switch. Push the “LED ACTIVATION”
button and allow one minute for the source to stabilize. If you are using an
external optical source, turn it on and make any adjustments necessary to set the
power level.
10.
Observe the LCD display. You should note an increase in reading from the one
recorded in Step 6 above. If the display is over-ranging, rotate the ‘”DISPLAY
SELECTOR SWITCH” clockwise to get a maximum in-range reading, then record
the result as
P
2
.
11.
Turn off the Fiber Optic Test Set by pressing the “ON/OFF” switch. Remove all
cable ends from the test set receptacles and replace the protective caps.
12.
To calculate the attenuation in dB/km (decibels per kilometer), use the following
formula:
This is typical attenuation for 1000 µm core plastic fi ber at 650 nm wavelength. Note that
low-loss fi bers may require more cutback length to give a suffi cient difference between
P
1
and
P
2
readings for accurate attenuation measurements. In those instances, simply convert
the cutback length to its equivalent in meters or kilometers and use the previous formula.
