Home

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.

Overview

• 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
• Cost: €6000

Features

• Text-based (SCPI-like) Ethernet interface for monitoring and configuration
• Protection circuit shuts down individual channels in case of: input power overload; reverse power overload; channel failure. Protection tripped indicator LED for each channel on the front panel, also readable via Ethernet. Protection circuit may be reset either using push-button on front panel or via Ethernet. The input power overload threshold is user-adjustable on a per-channel basis using the Ethernet interface. This allows users to ensure that the maximum power rating of sensitive loads, such as AOMs cannot be exceeded accidentally.
• Per-channel remote monitoring of: forward and reverse power; temperature; current and voltage.
• Remote shut down of individual channels via Ethernet, for example to avoid power dissipation from unused channels.
• Each channel is an independent unit for easy field replacement

Interlocks

Overview

Booster uses a series of interlocks to protect both itself and the loads it drives from fault conditions.

There are two classes of interlock, both acting on a per-channel basis: overloads, caused by excessive input or output forwards/reflected power, and device errors, caused by excessive temperature or current draw.

When an overload is detected the input RF is disconnected from the amplifier and redirected to an internal 50 ohm load. In case of an error, the input RF is disconnected and the amplifier power stage is shut down. Once an interlock has tripped, it must be manually cleared to resume normal operation, either by pressing the "interlock rest" button or via the remote programming interface. When error conditions are cleared, the power stage is first re-enabled before reconnecting the input RF.

The interlock status is displayed on the front panel LEDs as follows:

• All LEDs off - the channel has been disabled either via software or by pressing the standby button
• OK - the channel is enabled and operating normally
• OVERLOAD - one of the power interlocks has tripped and the input RF has been disconnected
• ERROR - an error condition has been detected and that the input RF has been disconnected and the channel shut down

Overloads

The input and 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. The input and reverse output power interlocks have fixed thresholds chosen to protect Booster from damage.

Remote programming interface

Overview

Booster provides a SCPI-like remote programming interface over Ethernet.

• All commands must be terminated with a new line (\n) character
• Booster responds to all commands. Commands containing a ? query Booster for information, other commands are acknowledged with the response OK. An error string is returned in case of a programming error, such as a malformed command
• Capital letters denote a part of the command that must be specified, lower case letters are optional. Commands are case insensitive. For example `INTERLOCK:POWER 0 -5', 'int:pow 0 -5' and 'INT:POW 0 -5' are all equivalent
• Triangular brackets denote a named parameter, which should be substituted for a value when forming the command
• | denotes a choice between two different parameters

Commands

• *IDN? returns a device ID string containing hardware and firmware revision information
• INTerlock:POWer <channel> <power> output forwards power interlock threshold in dBm e.g. 'INT:POW 0 33` sets the output forwards power interlock threshold for channel 0 to 33dBm. The threshold must lie between 0dBm and 40dBm otherwise an error is returned and the threshold is not adjusted. All updates to the interlock threshold are saved to non-volatile memory and retained across reboots of the device.
• INTerlock:POWer? <channel> returns the output forward power interlock threshold for a channel
• INTerlock:STAtus? ALL|<channel> returns the interlock status for either a single channel or for all channels (and-ed together). Response is ERROR if the interlock has tripped, otherwise OK.
• INTerlock:CLEar ALL|<channel> resets the interlock for either a given channel or for all channels
• MEAsure:TEMperature? <channel> returns the temperature of a given channel in C
• MEAsure:CURrent? <channel> returns the bias current for a given channel in amps
• MEAsure:VOLtage? <channel> returns the bias voltage for a given channel in volts
• MEAsure:INPut? <channel> returns the input power for a given channel
• MEAsure:OUTput? <channel> returns the forward output power for a given channel
• MEAsure:REVerse? <channel> returns the output reverse power for a given channel
• CHAnnel:ENAble ALL|<channel> <enabled> enables/disables (1 or 0) the power FET bias current/voltage for a given channel or for all channels
• CHAnnel:ENAble? ALL|<channel> returns 1 if the bias for a given channel is enabled or 0 if it is disabled. If ALL (default) then it returns the status for all channels anded together
• CHAnnel:BIAS? <channel> returns the bias voltage for a given channel
• CHAnnel:BIAS <channel> sets the bias voltage for a given channel. If this is outside the safe range (hard-coded into the firmware) then an error is returned and the bias setting is not changed. Note that there is additional protection when changing the bias voltage since the firmware interlock continuously monitors the bias current.

Please make sure to document things like the safe range for the bias voltage etc.

Firmware Update

Linux

Required libraries: dfu-util

• Download update.dfu file from github
• Place jumper into DFU pins on PCB and connect USB cable
• Run dfu-util -l and mark down alt number for Internal Flash option

dfu-util 0.9

Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc. Copyright 2010-2016 Tormod Volden and Stefan Schmidt This program is Free Software and has ABSOLUTELY NO WARRANTY Please report bugs to http://sourceforge.net/p/dfu-util/tickets/

Found DFU: [0483:df11] ver=2200, devnum=29, cfg=1, intf=0, path="3-5", alt=3, name="@Device Feature/0xFFFF0000/01004 e", serial="377533563436"
Found DFU: [0483:df11] ver=2200, devnum=29, cfg=1, intf=0, path="3-5", alt=2, name="@OTP Memory /0x1FFF7800/01512 e,01016 e", serial="377533563436"
Found DFU: [0483:df11] ver=2200, devnum=29, cfg=1, intf=0, path="3-5", alt=1, name="@Option Bytes /0x1FFFC000/01016 e", serial="377533563436"
Found DFU: [0483:df11] ver=2200, devnum=29, cfg=1, intf=0, path="3-5", alt=0, name="@Internal Flash /0x08000000/04016Kg,01064Kg,07*128Kg", serial="377533563436"

• Run command dfu-util -D update.dfu -a 0, with selected memory region alt number
• Wait for operation to complete, then remove jumper and reboot device

Windows

• Download application DfuSe Demo
• Download firmware update file from github
• Place jumper into DFU pins on PCB and connect USB cable
• Run DfuSeDemo
• Select Internal Flash from Select target(s) menu.
• In Upgrade or Verify Action click Choose and select firmware update file
• Click Yes in dialog box
• Wait for operation to complete, then remove jumper and reboot device