User guide

UPCOM TECHNOLOGIES
@BCL@1408FB8F 15
Theory of Operation
AC / DC Converter
The prime AC input power is delivered to a converter module that produces 300 VDC. This
module is an auto-sensing front end that has proven reliability and allows the amplifier system
to operate over a wide variety of input power conditions encountered around the world.
DC / DC Converter
The DC/DC converter module is a switched mode power supply that converts the 300 VDC to
12 VDC. This 12 VDC is the primary high current, DC voltage source that operates the booster
amplifier module.
A secondary module converts the 300 VDC to 24 VDC.
Units with input AC power use the above AC / DC and DC / DC topology.
Cooling System
The Outdoor SSPA’s cooling system represents a landmark in microwave telecommunication
amplifiers. It is a unique system of heat sinks that have been computer optimized to provide
extremely efficient cooling of all of the system’s functional blocks. This high efficiency cooling
system is primarily responsible for the small overall package size and reduced weight of the
unit.
The Cooling System is based on a forced convection technique in which both system fans
provide the air intake while the exhaust is brought out around the outer perimeter of the fans.
The fan is up to 300 CFM rated and operate into approximately 0.3 in. H20 back pressure. It is
also weather protected for reliability under a variety of conditions.
Amplifier
This module uses GaAs MESFET technology to boost the signal level to its final output power
level. A bias assembly connects the +12 V power supply with the FETs, and provides proper
bias voltages (including the negative voltage for the FET gates), and voltage sequencing at
turn on and turn off. The gain for this section is in the neighborhood of 25 dB.
Microcontroller ( Optional )
This section is responsible for serial communications and for processing of the Monitors and
Controls. Various alarms are monitored, such as overheating, along with select DC voltages.
The microcontroller disables the SSPA when any of these status indicators show a problem.
In addition, it is possible for the microcontroller to report output power levels in dBm and
control system conversion gain (when appropriate hardware is installed).
In Redundant configured units, the Microcontroller is also responsible for system switching
behavior.
Attenuator Module
This is an electrically controlled variable attenuator – an optional component that generally
receives control signals from the Microcontroller. It is responsible for both gain control
functions and supplemental gain versus temperature compensation.