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Booster is an eight channel RF power amplifier, providing up to 5W of RF between 40MHz and 500MHz. Mounted in a compact 2U high 19'' chassis, it is optimised for low cost and low power consumption, while providing good RF performance. It provides full interlocking and logging via a flexible ethernet-based remote interface.

Booster is currently available commercially from two suppliers: TechnoSystem and Creotech.

Overview

The specification below is somewhat pessimistic, detailed characterisation data can be found spread among various issues. To do: sort data and post here!

• Bandwidth: 40MHz to 500MHz
• P1db: 36dBm min
• Max CW output power: 38dBm min
• Gain @1dB compression: 40dB ±1dB typ (±1.5dB max)
• IP3: 48dBm min
• Crosstalk: -80dB max
• Input/output VSWR: 1.5:1 max
• Power supply: 100VAC-240VAC, 50Hz-60Hz
• Total power efficiency: >35% at 1dB saturation from mains to RF

Features

• Text-based SCPI Ethernet interface for monitoring and configuration
• Protection circuit shuts down individual channels in case: output power exceeds use-configurable threshold; reverse power overload; over temperature; channel failure.
• Per-channel remote monitoring of: input, output forward and output reverse powers; temperature; current and voltage.
• Remote shut down of individual channels via Ethernet
• Open source hardware and firmware
• Modular design with individually field-replaceable channels, for example to change the frequency band

Interlocks

Booster uses the following interlocks to protect itself and the loads it drives from damage:

• output forward power
  • user-adjustable threshold up to 39 dBm
  • this interlock is primarily intended to protect sensitive loads, such as AOMs, which could be damaged by excessive RF power
• output reverse (reflected) power
  • fixed 30dBm threshold
  • this interlock is primarily intended to protect Booster itself from damage
• current consumption
  • internal 30V and 6V supplies
  • hardware fold-back protection on the 30V PA supply
• temperature
  • software protection disables channel when temperature reaches 60 C
  • thermal switch cuts power to entire chassis at 80 C

When any interlock trips, the input RF is disconnected from the amplifier using an internal RF switch. In case of an error condition, such as excessive current consumption or temperature in the amplifier, the amplifier power stage is also shut down. Once an interlock has tripped, it must be manually cleared to resume normal operation, either by pressing the "interlock reset" button or via the remote programming interface. Note that disabling a channel (via the remote interface or by pressing the standby button) does not clear the interlock status, despite the fact that the OVERLOAD and ERROR LEDs turn off as long as the channel remains in standby. Once the channel is re-enabled, the interlock LEDs switch on again.

Yellow LEDs on the front panel indicate that an RF power interlock has tripped, red LEDs indicate an error condition, such as over current or over temperature. The interlock status can also be found using the remote interface.

Diagnostics

Note that RF power detectors are sensitive >+10dBm.

Overview

When Booster is first powered on, all interlocks are cleared. (Channels can be also enabled at startup, based on VCP command powercfg 1/0. See the VCP section for more information.

Overload

The output RF powers are interlocked using fast (ns) hardware interlocks. The output reverse power is interlocked in software on the microprocessor. The threshold for the output power interlock is user-adjustable via the remote programming interface to allow protection of sensitive loads, which cannot tolerate Booster's full output power.

Front panel switches

Booster's front panel houses two push switches:

• INTERLOCK CLEAR: equivalent to the INTERLOCK:CLEAR ALL instruction
• STANDBY: toggles between enabling and disabling all channels, equivalent to the CHANNEL:ENABLE ALL and CHANNEL:DISABLE ALL instructions.