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Remove the fuses from the holder. Measure the resistance across the fuses. If the resistance is
> 1.0 ohms, replace the fuse. Reinstall the fuses in the DLA. If the fuses are operational and
the power supply remains off, replace the Distribution Line Amplifier.
4.3.1.2
RADIAX
Alarm Asserted
Assertion of the RADIAX input alarm indicates a loss of signal (Signal Center Frequency is
2416.64 MHz) from the preceding Distribution Line Amplifier and or base station radio. The
following trouble shooting procedure assumes that the amplifiers are cascaded in the forward
configuration normal direction mode and that the amplifier has been correctly configured as
indicated in 2.5.
Visually inspect the cable assemblies from the preceding amplifier or radio for loose connections
and or cable breakage. Tighten all cable connections. Replace broken or damaged cables as
necessary.
If all cable assemblies are secure and intact, disconnect the cable at J4 of the DLA. Using a
power meter or spectrum analyzer attached to the cable, verify the presence and expected level
of the RF signal (F
= 2416.64 MHz, 0 dBm nominal). If the signal is present and the alarm is
c
configured correctly (refer to section 2.5.2.2.2) the amplifier should be replaced. If the RF signal
is not present continue to determine the origin of the signal loss.
4.3.1.3
Amplifier Alarm Asserted
Assertion of the Amplifier Alarm can be caused by:
•
Loss of an input signal on the PA Channel (RADIAX Alarm Asserted)
•
Failure of the PA module
•
Loss of the Pilot Tone Signal to the LNA module
•
Failure of the LNA module.
4.3.1.3.1
Loss of PA Input Signal
When the RADIAX Alarm is asserted, the loss of input signal can also cause the PA module to
also assert its output alarm. With a loss of input signal, the PA module gain is insufficient to
generate a signal level above the level represented by the output threshold detector in the PA
module. If both the RADIAX alarm signal and the Amplifier Alarm signals are asserted, the user
should determine the cause for the loss of input signal.
4.3.1.3.2
PA Module Failure
If the input signal to the PA channel is at the expected level and the PA channel output alarm is
asserted, either the PA module has failed or it is incorrectly configured. The PA module output
alarm can be monitored with a DVM at J4-1 of the Relay/IO board. A voltage level < 1 VDC
indicates a fault condition for the PA channel.
The output signal can be measured with a power meter or spectrum analyzer. If no signal is
detected at the Distribution Line Amplifier output port (J3 for the forward direction) the unit should
be returned to Andrew Corporation. If a signal is present, the user should confirm that the
amplifier output is below the levels indicated on the configuration sheet attached to the
Distribution Line Amplifier. If the input and output signal levels are at the levels specified on the
Document use is restricted to that described on cover
MAINTENANCE AND TROUBLESHOOTING
4-5
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