Comtech EF Data KPA - Manual (Page 20)

Ku-Band Solid-State Power Amplifier Revision 1
Introduction MN/KPA.IOM
1–2
1.2 Functional Description
Each KPA ISSPA is constructed with highly reliable Gallium Arsenide Field Effect Transistors
(GaAs FETs). With Third-Order Intermodulation products from 4 to 6 dB better than TWT
ratings, the Comtech EF Data unit replaces TWTs with saturated power levels of up to twice the
KPA’s rated output. These KPAs also provide a Mean Time Between Failure (MTBF) that is 4 to
5 times greater than the typical TWT MTBFs.
The KPA is designed to be rack-mounted in a standard 19-inch (48 cm) rack or cabinet by hard-
mounting the unit to the rack’s front mounting rails using the front panel mounting holes;
optionally, rack slides may be installed onto the chassis that allow servicing of the unit without its
removal from the rack. Handles at the front of the unit facilitate easy installation into and removal
from the rack.
All user controls, indicators, and displays for local and remote operation – as well as the RF Input
and Output sample test ports – are located on the front panel of the unit. User external interface
connectors are located on the chassis rear panel.
Two internally mounted exhaust fans provide cooling – cool air is taken in through the front panel
and exhausted out the rear panel.
An AC power connector and On/Off switch are located on the chassis rear panel. A six-foot AC
power cord is supplied with the unit.
On the pages that follow, Figure 1-2 and Figure 1-3 depict the block diagrams for the available
KPAs. Each KPA chassis consists of a power supply, fan assembly, front panel assembly,
monitor/control processor (MCP), and a Comtech EF Data SSPA module. The KPA is designed
using a Comtech EF Data low loss combining technique and an MCP based temperature versus
gain compensation.
The front panel features:
• A Vacuum Fluorescent Display for user-friendly visual status update (Liquid Crystal
Diode display for KPA-020IN and older KPA-040/-080/-100 units)
• The six-button cursor array is used to set or change operating parameters
• Six Light-Emitting Diodes (LEDs) provide quick reference to binary status points
• Input and output sample ports at –20 dBc and–40 dBc provide easy test point access
Each unit has the ability to function as a 1:1 or 1:2 redundancy controller in the backup mode.
The optional redundancy configuration is implemented by attaching a ganged waveguide/coax
transfer switch(es) to input and output connectors of the amplifiers with a combination coaxial
cable and waveguide kit. When the backup KPA is commanded into the controller mode, it
monitors the online KPAs for faults. A faulted online unit may be disconnected and replaced
without affecting the online power amplifier. For detailed information about using the KPA in 1:1
or 1:2 redundancy, see Appendix B. KPA REDUNDANT OPERATIONS.