EXFO FTB-700 for FTB-1 - Manual (Page 195)

OTDR 187
14 Using the OTDR as a Light
Source
If you want to perform measurements with a power meter and your OTDR
as a source, the OTDR port can transmit a special tone. This port can be
used only to transmit—not detect that tone.
C
AUTION
Never connect a live fiber to the OTDR port without a proper setup.
Any incoming optical power ranging from –65 dBm to –40 dBm will
affect the OTDR acquisition. The way the acquisition will be
affected depends on the selected pulse width.
Any incoming signal greater than 10 dBm could damage your OTDR
permanently. For live-fiber testing, refer to the SM Live port
specifications for the characteristics of the built-in filter.