122AA-01000AB MKS Instruments Absolute Pressure Transducer

The MKS Instruments Baratron 122A Absolute Pressure Transducer uses a single-sided dual-electrode Inconel sensor coupled with a new fixed-frequency bridge signal conditioner. The 122 provides operation which is inherently temperature stable at zero pressure, capable of withstanding high overpressure conditions with minimal or no shifts in output over its range, and high resistance to corrosive environments.

The variable-capacitance sensor design incorporates a tensioned metal diaphragm (Inconel), one side of which is exposed to the gas whose pressure is to be measured. The other (reference) side of the diaphragm contains a dual electrode assembly (previously found in premium transducers only) sealed in a high vacuum reference cavity which is maintained by a chemical getter system.

The signal conditioning electronics board contains a fixed-frequency oscillator, balance-sensing circuit, linearization circuitry and amplifiers which provide a 0 to 10 Volt DC full scale output. The signal conditioner is inherently temperature stable at balance (pressure = 0 Torr) and is self- compensating with temperature changes at other pressures.

A drawn aluminum can forms the protective cover for the transducer and a PC board mounted removable terminal block allows connections to be easily made for ± 15 VDC power inputs and the 0 to 10 VDC pressure signal output. In addition, the aluminum cover works in conjunction with an inner PC shield board with RF bypass capacitors to virtually eliminate RFI and EMI.