Nautel NG1000, Troubleshooting Manual

Page: 34 / 164

NG1000 Troubleshooting Manual Responding to alarms
Page 1-12 Issue 0.4 2010-10-12
TXA (or TXB) IPA
Output Low TRANSMITTER A
TRANSMITTER B This alarm occurs when the associated transmitter’s
IPA output power is less than 40% of the set point
level (set point = 150 W; alarm threshold = 60 W. The
alarm clears when the IPA output power increases to a
level that is greater than 90% of the set point.
TXA (or TXB) Main
Audio Low EXTERNAL This alarm occurs when the main audio input level is
less than the threshold level specified for VOX keying
(configurable between -50 dBm and -25 dBm). If
enabled, this alarm will mute the associated
transmitter’s output.
TXA (or TXB) No Int
10 MHz TRANSMITTER A
TRANSMITTER B This alarm occurs when the TCXO on the exciter/
control PWB is significantly off frequency or missing.
The associated transmitter’s RF output will be
inhibited.
TXA (or TXB) PA Over
Temp TRANSMITTER A
TRANSMITTER B This alarm occurs when the heatsink temperature
exceeds the safe limit for the PAs (100°C or 212°F).
The associated transmitter’s RF output will be
inhibited until the alarm condition clears.
TXA (or TXB) PA
Power Limit TRANSMITTER A
TRANSMITTER B This alarm occurs when the transmitter has limited the
PA forward power to an acceptable level, based on
VSWR, PA failures or PA dissipation limits.
TXA (or TXB) PA
Volts A or B Fail TRANSMITTER A
TRANSMITTER B This alarm occurs when the associated PA voltage
supply has fallen more than 4 V below the expected
voltage for the corresponding power supply control
voltage.
TXA (or TXB) PA
1 - 8 Fail TRANSMITTER A
TRANSMITTER B This alarm occurs when the associated transmitter’s
corresponding PA has been flagged with a failure
condition, due to a low current reading that is less than
half of the average of the operational PAs (minimum
threshold is 500 mA).
TXA (or TXB) PLL
Unlock TRANSMITTER A
TRANSMITTER B This alarm occurs when the exciter/control PWB’s
main PLL is unlocked, inhibiting the associated
transmitter’s RF output due to the possibility of being
off frequency.
TXA (or TXB) Preamp
Bias Flt TRANSMITTER A
TRANSMITTER B This alarm occurs when the associated transmitter’s
preamp is unable to reach the desired bias current
(35 mA) for a gate bias voltage range between 2 V and
3 V during a bias routine.
Alarm (with Prefix) Alarm/Status LED Description and Troubleshooting Action