COMBA CriticalPoint V3 7 BDA - Page 218

CRITICALPOINT 700/800MHZ BDA/DAS/BBU V3 USER MANUAL
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568 Gibraltar Drive, Milpitas, CA 95035 | +1 408 526 0180
Rev. 1-0-2 Rev. Date: 11-1-2024
Page: 218
PA Alarm DL 700MHz, PA Alarm DL 800MHz, PA Alarm UL 700/800MHz
Cause
A fault is detected in the PA. The PA alarm is to monitor the final stage power amplifier for both
downlink and uplink. The following conditions will trigger a PA alarm:
1) High Temperature (Using internal threshold)
2) High Current
3) High Bias Voltage
4) Overdrive (high output power), could be due to oscillation
5) High Return Loss (when the DL output power is between 28dBm – 33dBm)
6) Other hardware issues
When PA Protection is ON:
The PA will shut down upon alarms, and reboot at 1min, 5min, 10min, 20min, 30min, and
1hour. After that, if the PA still cannot be turned on, PA will be permanently shut down.
When PA Protection is OFF:
The PA will NOT shut down when the above mentioned faults are detected.
Remedy
Check isolation and make sure the any gain setting meets < (isolation – 20dB), then reset PA in
“tools – DL PA reset 700MHz or 800MHz / UL PA reset”. If the alarm doesn’t go away, contact
Technical Support.
PA Shutdown Alarm DL 700MHz, PA Shutdown Alarm DL 800MHz, PA Shutdown Alarm
UL 700/800MHz
Cause
1) RF switches are OFF.
2) The PA is shut down due to an internal alarm (During PA Protection, or oscillation shutdown)
Remedy
Turn on the RF switches.
Check for PA alarms (refer to PA Alarm) and correct.
Check Oscillation alarms and correct.
VSWR Alarm DL 700MHz, VSWR Alarm DL 800MHz
Cause
The DL VSWR will trigger when both the criteria below are met:
1) The 700MHz or 800MHz Downlink Composite Output power is > 5dBm.
2) The Return Loss is <6dB. Return Loss = Forward Power – Reverse Power
Remedy
Temporarily install a 50ohm termination load on the MT port and check if the alarm is still
present. If the alarm clears, perform troubleshooting of the passive components and coaxial
cables starting from the MT port. If the alarm does NOT clear with 50ohm load, contact
Technical Support for further troubleshooting.