Table of Contents
Advertisement
LPOD C-, X-, or Ku-Band Outdoor Amplifier / Block Up Converter (BUC)
Introduction
1.4.2 SSPA Module
The amplifier module performs the core function of the unit. An isolator is at the
RF input to ensure good voltage standing wave ratio (VSWR). The RF signal then
passes through an electronically controlled attenuator that adjusts the overall
attenuation according to the user input. After some amplification, a second
attenuator is automatically controlled via a look-up table to maintain the
amplifier gain at a constant level over temperature variations.
The RF signal is then amplified by a multi-stage design that utilizes proprietary
combining techniques to meet the rated power requirements. The output
circuitry contains a coupler to provide a sampled signal for monitoring purposes.
A power detector circuit also is included and the reading can be accessed via
remote communication. A high power circulator and load is located at the output
to provide good VSWR and protection from external mismatch.
1.4.3 Cooling System
The LPOD contains a robust heat sink and thermal design to maintain a low
operating temperature. The PS 1 contains one temperature-controlled fan, and
the PS 1.5 and PS 2 contain two temperature-controlled fans that are monitored
by the M&C board. The fans draw cool outside air in across the power supply and
specialized heat sink. The amplifier module temperature is monitored and, if for
any reason the amplifier temperature exceeds a safe preset limit, the amplifier
module supply is shut down to protect the unit from thermal failure.
1.4.4 Power Supply
The LPOD features a power supply that is power factor corrected. It supplies
several voltages necessary for the unit to operate:
• The 10V power supply output state is controlled by circuitry within the RF
module. If the RF module does not have the –5.8V supply for any reason,
it will not allow the 10V power supply to turn on. This protects the power
transistors within the RF module from failure due to improper power
supply sequencing.
• The +24V output powers the cooling fans, is the source of power for
waveguide switching when the SSPA is used in redundant configurations,
and is dropped to +22V for LNB bias.
1–7
MN-LPOD
Revision 14
Advertisement
Table of Contents
