User Manual
Table Of Contents
- 1. INTRODUCTION
- 1.1 Scope and Purpose of document
- 1.2 Limitation of Liability Notice
- 2. SAFETY CONSIDERATIONS
- 3. MASTER SITE RACKS (50-078001)
- 3.1 Master Site Description
- 3.P Master Site Rack Photos
- 3.2 Master Site Electrical Specification
- 3.3 Master Site Mechanical Specifications
- 3.4 Master Site Parts List (50-078001)
- 3.5 Channel Frequency Listing
- 3.6 Master Site Drawings
- 3.7 800MHz Air I/F + BSCE Uplink Shelf (50-078002)
- 3.8 800MHz 8Ch. Channel Module Sub-Rack (50-078003)
- 3.9 800MHz 40Watt Power Amplifier/Driver Shelf (50-078004)
- 3.10 VHF Simplex Shelf (50-078010/1)
- 3.11 VHF Simplex Shelf (50-078010/2)
- 3.12 VHF Duplex Shelves (50-078011/1-4)
- 3.13 VHF Air Interface Shelf (50-078012)
- 3.14 VHF Combiner Shelf (50-078013)
- 3.15 VHF PSU Shelf (50-078014)
- 3.16 VHF/800MHz Tx Multi-coupler (50-078015)
- 4. BAND SELECTIVE BI-DIRECTIONAL LINE AMPLIFIER
- 5. MASTER SITE UPGRADE
- 5.1 Master Site Upgrade Rack Assembly (50-078021)
- 5.1.1 Master Site Upgrade Rack Description
- 5.1.2 Master Site Upgrade Rack Electrical Specification
- 5.1.3 Master Site Upgrade Rack Mechanical Specification
- 5.1.6 Master Site Upgrade Rack Assembly (50-078021) Parts List
- 5.1.6a Upgrade Channel Module Shelf/Sub-Rack 50-078023 Parts List
- 5.1.7 Master Site Upgrade System Diagram, Drg. # 50-078081
- 5.2 Upgrade Channel Frequencies
- 5.3 Master Site HPA Interface Shelf (50-078005)
- 5.4 High Power Amplifier Shelf (50-146703)
- 5.1 Master Site Upgrade Rack Assembly (50-078021)
- 6. INSTALLATION
- 7. MAINTENANCE
- APPENDIX A
- APPENDIX B Initial Equipment Set-up Calculations
- APPENDIX C - BATTERY BACKUP
- C.1 GENERAL DESCRIPTION
- C.2. BATTERY BACKUP PHOTOGRAPHS
- C.3. SPECIFICATION
- C.4. GENERAL DRAWINGS
- C.5. BBU ALARMS & MONITORING SYSTEM
- C.6. INSTALLATION
- _
- C.7. MAINTENANCE
Mission Valley Radio Repeater Equipment + UpgradeUser/Maintenance Handbook
APPENDIX C Battery Backup
Handbook No. 50-078021HBKM Page 79 of 85
C.3.3 Technical Description
AFL Cell Enhancer/repeater equipment often requires backup against failure of the mains AC supply.
Since the equipment runs on a 12V DC supply the most efficient method of providing backup is by a
bank of dry lead acid batteries of adequate capacity.
The Battery Backup Power Supply Unit incorporates a 400 Watt DC power supply and a
Charger/Regulator with a bank of two 12V 40AH batteries connected in parallel. The 400 Watt
SMPSU power supply will provide 12V DC to power the repeater under normal running conditions
from the mains supply. The batteries will provide 12V DC if the mains supply fails.
To reach maximum capacity the batteries need a charging voltage of 13.5V and this is provided by a
commercially available TRACO type TIS300-124 power supply with an output current capability of
10A maximum. The disadvantage with lead acid batteries is the high terminal voltage during charging.
AFL repeaters employ a diode combiner to sum the 12V DC output of the SMPSU DC power supply
and the battery bank DC output. The diode combiner is used to achieve "no break" changeover on
mains failure, however, if during charging the battery output has a greater voltage than the SMPSU
DC power supply the repeater will draw current from the batteries and not the SMPSU. A further
disadvantage is that the power dissipation in the repeater amplifiers is 30% greater with a 13.5V
supply and some power amplifier devices are rated to 14V maximum collector voltage leaving little
margin for safety.
To overcome these problems the Battery Backup Power Supply must regulate the battery voltage to
be slightly below that of the SMPSU. At the same time when the AC supply is off and the equipment is
running from batteries the voltage drop across the regulator must be a minimum to achieve maximum
backup time as the batteries discharge.
A further requirement is to prevent the effect known as "deep discharge" which shortens battery life.
This means the load must be disconnected from the batteries when they become discharged to a
terminal voltage of approximately 10.5V.
The charger power supply charges the 2 series connected batteries through blocking diodes. The
diodes prevent unwanted current flows between circuit elements. The battery charger DC output is
connected through the Battery Output ON/OFF switch to the Charger Control Board via a diode where
it powers the low voltage disconnect comparator. The comparator senses the battery voltage via a
potential divider and compares it to a fixed 5V reference. Adjustment of the potentiometer VR1 sets
the minimum battery voltage at which the low voltage disconnect relay remains energised and the
output to an 18V regulator is enabled.
In the absence of an AC input the supply to the comparator is maintained from the batteries via a
second diode through the contacts of the low voltage disconnect relay. When the comparator
releases the low voltage disconnect relay the comparator supply is interrupted. The low voltage
disconnect relay will then remain de-energised (Battery Output Off) until either the AC supply returns
or the Reset pushbutton is pressed. On actuation of the Reset pushbutton the output will be restored
provided the battery voltage exceeds the comparator threshold set by the potentiometer VR1.
Output from the low voltage disconnect relay is routed to the 9V regulator which provides a stabilised
9 Volt output determined by two divider resistors. This supply feeds a voltage doubler circuit
configured from a square wave multi-vibrator and two chopper field effect transistors. Two diodes
form the voltage doubling rectifier so that in normal operation approximately 33 Volts is available
across doubler circuit capacitors.
The 16 Volt supply is routed via the control element transistor to the gate of a Power MOSFET which
is the series pass element for regulating the 13.5V battery voltage to 12.5 Volts at the final output.
The FET is chosen for its ability to pass high currents (>30A) with a very low voltage drop (100mV).
To achieve this performance requires that the gate is at least 6V more positive than the drain &
source terminals. This is the reason for the Voltage doubler supply for driving the gate.
The output voltage is sensed by a second potential divider and compared with the reference voltage
from a zener diode to drive the control element transistor for the gate voltage of the pass element.
Adjustment of the second potentiometer VR2 sets the output voltage to the required value.