Comtech EF Data HPCST-5000 - Manual (Page 22)

Introduction High-Power TWTA Satellite Terminals
1–6 Rev. 1
1.2 Component Descriptions
1.2.1 Low-Noise Amplifier (LNA) Assembly
A typical redundant LNA assembly consists of a transmit reject filter, waveguide switch,
and two LNAs. Optionally, a coaxial switch, 1:4 power splitter, and a block converter are
available.
For more information on the LNA assemblies, refer to the following manuals:
•
CST-5000 C-Band Satellite Terminal Installation and Operation Manual
•
CST-7000 C-Band Satellite Terminal (Insat) Installation and Operation Manual
•
KST-12000 Ku-Band Satellite Terminal Installation and Operation Manual
1.2.2 Radio Frequency Terminal (RFT)
The RFT is a weatherproof enclosure which houses:
•
Up and down converters
•
Frequency synthesizer
•
IF and RF interface
•
M&C system
•
Power supply
•
Cables
In the transmit (uplink) direction, the terminal accepts a 70 MHz IF signal and transmits
it in the uplink transmit frequency band. This output is coupled through a type N
connector to the external TWTA assembly. This system provides the high-power output
to the antenna through a waveguide switch. A 40 dB coupler is included at the output of
the waveguide switch to meet INTELSAT specifications.
A high-power termination is included on the offline channel port of the waveguide
switch for testing. Each redundant thread has been factory-compensated for TX gain
stability over temperature. EFData recommends that when replacing a faulted unit, the
RFT, TWTA, and associated coax link must be replaced as a set. Otherwise, gain
stability can not be guaranteed.
In the receive (downlink) direction, the terminal accepts an RF signal in the downlink
frequency band, and down-converts it to a 70 MHz IF output. The LNA assembly has an
RF RX type N coax output to each RFT receive input.