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385700-4006-006
configuration sheet, the PA module alarm may be indicating a faulty setting on the output level
monitor. Refer to section 2.5.2.2.4 for details on setting the output alarm.
monitor is correctly configured, the Distribution Line Amplifier should be returned to Andrew
Corporation.
4.3.1.3.3
Loss of Pilot Tone Signal
In a correctly configured DLA, the pilot tone is monitored by the LNA output detector circuit.
Without the pilot tone there may not be sufficient signal at the LNA module output. As a result,
the LNA module will signal an amplifier failure. The pilot tone signal can be monitored with either
a power meter or a spectrum analyzer.
Figure 1-3 DLA Internal View shows the location of the pilot tone module and its output port J3.
The expected output at the pilot tone module J3 port is a nominal - 10 dBm signal at 2401 ± 2
MHz. If this signal is not present, the Distribution Line Amplifier should be returned to Andrew
Corporation. If the signal is present, reattach the cable from J3 of the pilot tone module to the
LNA module AUX RF input port. Tighten the connections as necessary.
4.3.1.3.4
LNA Module Failure
If the pilot tone signal to the LNA channel is at the expected level and the LNA channel output
alarm is asserted, either the LNA module has failed or it is incorrectly configured. The LNA
module output alarm can be monitored with a DVM at J4-2 on the Relay/IO board. A voltage
level < 1 VDC indicates a fault condition for the LNA channel.
In order to measure the output of the LNA channel, it is necessary to inject an external signal into
the LNA channel. The external signal can be either a CW signal at a frequency in the passband
of the LNA channel (see Table 1-2 Distribution Line Amplifier Specifications in section 1.5.2) or it
can be the output signal of an MDR. In either case, the signal input level to J3 of the DLA
(normal forward configuration) should be -50 dBm.
Based on the gain setting specified on the configuration sheet attached to the DLA, the external
signal can be verified with a power meter or spectrum analyzer. If no signal is detected at the
Distribution Line Amplifier output port (J4 for the forward direction) the DLA 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 measured level is below the expected value the Distribution Line Amplifier should be
returned to Andrew Corporation. If the input and output signal levels are at the levels specified
on the configuration sheet, the PA module alarm may be indicating a faulty setting on the output
level monitor. Refer to section 2.5 for details on setting the output alarm.
monitor is correctly configured, the Distribution Line Amplifier should be returned to Andrew
Corporation
Document use is restricted to that described on cover
MAINTENANCE AND TROUBLESHOOTING
If the output level
If the output level
4-6
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