Nautel VS1, Troubleshooting Manual

Page: 32 / 109

VS1 Troubleshooting Manual Responding to alarms
Page 1-24 Issue 10.0 2018-10-29
SRC1 Unlock Exciter (amber) This alarm indicates that no valid AES/EBU stream data is being
detected on the selected AES/EBU. The VS1 takes no action on
this alarm.
SWR Foldback Output Network
(amber)
This alarm occurs if the transmitter's average reflected power
exceeds the SWR foldback threshold (51 W) due to a gradually
degrading load match. The forward power of the transmitter will be
limited to a level such that this threshold is not exceeded. If the
load match improves while the transmitter is producing RF output,
the forward power will increase. If the transmitter folds back to a
forward power that is equivalent to a 3:1 VSWR at the SWR
Foldback threshold (forward power of 204 W), an
SWR
Shutdown
alarm occurs.
Refer to Table 1.4 on page 1-30 to determine the approximate
operating forward power levels for FM+HD systems [with more
aggressive (Efficiency Priority) and less aggressive (MER Priority)
HD PowerBoost] at various injection levels.
Inspect the antenna and transmission line system for damage or
de-tuning. If there are no major issues with the antenna network
that would cause an impedance change (icing for example),
suspect the combiner interface PWB (A12) (see “Combiner
Interface PWB Replacement” on page 1-47 ).
SWR Shutback Output Network
(red)
This alarm occurs if the transmitter's reflected power suddenly
exceeds the SWR shutback threshold, which is the reflected
power that is equivalent to a 2:1 VSWR at max power (156 W)
due to a transient SWR condition (arc or lightning) within the
output transmission line or antenna system. Attempt to reset the
latched condition by pressing
Reset
[using the remote AUI’s
Reset
button (see “
Reset :” on page 2-18
of the Operations and
Maintenance Manual) or using the local front panel display (see
“Resetting Alarms” on page 2-96 of the Operations and
Maintenance Manual)]. Inspect the output transmission line for
punctures or damage. If no damage can be found, suspect the
combiner interface PWB (A12) (see “Combiner Interface PWB
Replacement” on page 1-47 ). See also
Cutback Active
alarm.
Unsigned DSP
Image
(Exc Bad DSP
Image)
Exciter (red) This alarm indicates that the exciter is operating with ‘unsigned
code’, but is otherwise operational. This alarm may only be
displayed if the transmitter is operating with a ‘beta’ version of
factory software.
Alarm Name
AUI and
(Front Panel)
Front Panel
LED (color)
Description and Troubleshooting Action