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OP940-SW
Problem
Possible Cause
Solution
Return
Loss on
connectors
takes some
time to
stabilize
Dirt and damage
Inspect all endfaces including any SAVer cables
and the front panel connector on the instrument.
Clean or repolish any dirty or damaged connectors.
Dwell times
Increasing the IL and RL Dwell times in software or
on the Settings screen of the unit (see page 27) can
improve stability by allowing the detectors more time
to settle.
Unit shows
low output
power
Dirt and damage
Inspect all endfaces including any SAVer cables
and the front panel connector on the instrument.
Clean or repolish any dirty or damaged connectors.
Unit shows
low output
power
Misaligned adapters
Sometimes FC connectors can screw into place
without being properly keyed. This will result in low
output power and unstable results. Disconnecting
the FC connector and reconnecting it with the
proper key alignment should yield a more stable
connection.
Further, hybrid bulkheads (especially SC-LC) often
have issues with alignment. If the cores of the fibers
do not align properly, the power will be considerably
lower.
Mismatched fiber size
When launching light into optical fiber, if the DUT
or launch cable has a smaller core size than the
source, there can be a considerable drop in power.
Changing from 62.5/125µm fiber to 50/125µm
can result in a drop of about 3-5dB of power, and
launching multimode light into a single mode cable
can result in a drop of 20dB of power.
Return Loss
will not
reference
APC connector on
DUT
By default, OptoTest units require a large reflection
to reference return loss. Using one of a few different
options, the unit can reference return loss with
APC connectors. Instructions for doing this on
a standalone unit can be found in this manual –
Example 2: Referencing Return Loss with APC
Reference Cables on page 36.
Tr
ou
b
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sh
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Troubleshooting (cont.)
