Terrasat IBUC 3, Operation Manual

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6-4
|
IBUC
3
, IBUC
3 G
Operations Manual: Troubleshooting
Engineered to Endure
Damaged Cables
RF coaxial cable damaged due to improper handling (such as contact damage due to
improper mating; cable insulation that is damaged, crushed, cut, or charred; cables
were not discharged prior to connecting them; or conductors that are nicked, gouged,
damaged, or severed) may impair system performance and reliability. Do not attempt
to repair broken or damaged coaxial cables unless absolutely necessary. Replace the
entire cable whenever possible.
Damaged cabling and incorrectly tightened connectors can leak RF energy, which may
lead to excessive levels in their immediate vicinity.
10 MHz Reference Signal is at the Wrong Level or Missing
A 10 MHz input is used to provide a stable reference frequency to which the
synthesizer synchronizes. The 10 MHz reference signal level should be between
- 12 dBm to +5 dBm.
When the IBUC senses that the synthesizer has gone out of lock, a Synthesizer Lock
alarm is triggered. This alarm then initiates a series of routines that leads to the muting
of the power amplifier (that is, the IBUC is automatically shut - off). Table 6.1 lists four
possible scenarios caused by changes in the 10 MHz reference signal or whether the
synthesizer is locked.
Table 6.1 Possible Scenarios for IBUCs with an External 10 MHz Reference Signal
10 MHz Reference
Signal Level
Phase-Locked Local
Oscillator
Results
Low Locked
Causes a minor alarm (10 MHz Detector). Unit
is still transmitting. Check the 10 MHz signal
level. Resultant phase noise may be degraded.
Low Out-of-Lock
Causes a major alarm (Synthesizer Out of
Lock). Power amplifier is muted and the IBUC is
automatically shut-off. Check the 10 MHz
reference signal level and whether the 10 MHz
reference signal is enabled at the modem.
!
CAUTION
Never disconnect RF cables or connectors associated with a transmitter
in operation since this may result in an RF burn through direct contact
with RF conductors.