Views of the insides of the WASP chassis

CSO water-cooled version
Click on most images for detailed view

WASP2 spectrometer front panel.   From left to right, soft reset button, power lamp (+5V), and two SMA connectors for auto- or cross-correlation signal input.

Rear view of WASP2 spectrometer.  From left to right, cooling water inlet, power supply, two BNC connectors for auxiliary I/O, 9-pin female D connector for serial I/O to the internal microcontroller, two parallel 15-pin female D connectors for synchronization signals, and the cooling water outlet.

Top view of the inside of a WASP2 spectrometer chassis.  From top to bottom:

Bottom view of the spectrometer chassis.  Two 8-way power splitters send signals to the correlator cards with appropriate delays provided by the coiled cables.  A single long cable delay, visible toward the bottom of the image, shifts the delay center to one end of the spectrometer's series of lags.  The clear plastic tubes at the top and bottom carry cooling water to manifolds at the front of the chassis (right).

Block diagram of the microwave signal processing electronics.  Images of the downconverter and amplifier modules are below.

Downconverter plate with 8 GHz DRO, downconverter module, and 4-8 GHz anti-aliasing filters.

A close-up view of DRO and downconverter module showing monitor coupler and LO splitter feeding the two mixers.  A MMIC biphase modulator for phase switching  is in the 4-8 GHz input path of the upper channel.

A close-up image of the downconverter plate in the chassis with an arrow showing the DRO monitor port. 
The amplifier module is at the bottom of the image, with the tail of the arrow is on the amplifier module's cooling plate.

Amplifier module.  From left to right, gain equalizer, step attenuator, 4 GHz low pass filter, amplifier, switch, and amplifier.  The circuit board in the center carries  the computer interface and a temperature sensor.

Top and bottom views of the correlator boards without cooling or thermal covers.  Each card carries 16 multipliers (bottom) and 16 corresponding preamplifiers, synchronous detector, and analog-to-digital converters (top).   More information is available on the WASP spectrometer technical page.

Close-up view of board water cooling.  Coolant runs through the copper tube, with the brass bars serving to collect the heat from the ADCs.  The bars are bonded to the center two ADCs on each side with thermal epoxy; heat sink compound between the other ADCs and the bars insures good thermal contact.  We chose to cool the ADCs for two reasons: they dissipate a moderate amount of the power, and their many legs efficiently pull heat from the board itself.


Spectrometer internal microcontroller card.  The Intel 80251SB microcontroller is a Phytec module that performs all real time functions.  An Altera PLD, programmable through the connector at the board center, generates clock signals for the correlator ADCs.

Views of the insides of the four-WASP power supply

CSO version
Click on most images for detailed view

Front panel of  the power supply for four WASPs.  The supply is an Astec 800 W switching supply.  Meters monitor power supply voltages and current.  Lamps show AC and DC power.  The front-panel switch switches the DC power from standby to active.  A rear panel switch controls AC power.

Rear panel of the power supply.  In this view the fan on the left hand side is the exhaust, and the fan on the right is the intake.  The modular line input has the line switch and line fuse.  Additional fuses are inside the box in series with each of the four power supply connectors.

Top view of the power supply chassis.  The box at the top of the image is the power supply itself, a switching supply that supplies +5 V, -5 V, and +15 V.  Connections to the green circuit board on the right enable monitoring of voltages and output currents.  In addition to the usual fuse on the AC power, each output line has a separate fuse, mounted in the grey block at the chassis' center.  Unlike the spectrometers, which have water cooling, the power supply is air-cooled.  Input and exhaust fans on the chassis rear (left) help the power supply's internal fans circulate sufficient cooling air. 

Close-up of internal fuse block.  The power supply lines for each spectrometer are individually fused.

Questions or comments?  Please contact Andrew Harris.