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This is an MKS HPS 903 inverted magnetron cold cathode gauge vacuum transducer with KF-25 flange.

Our price: $385

As received by us, this transducer appeared to have been "gently used". The plastic case shows only a few light scuffs and scratches from handling. Sealing surfaces are in good condition - a few light scratches, but nothing that prevents leak-free sealing. The electrodes show only very light discoloration - not the heavy discoloration indicative of long periods of use, or of operation at very high pressures for significant periods of time.

This transducer was tested on a clean, turbomolecular pumped high vacuum system. All functions appeared to work correctly.

This is not just a "gauge tube", but instead, a complete transducer. It requires that DC voltage (14 to 30 VDC, 3 W maximum) be supplied to operate the electronics. It produces an analog output DC voltage that varies as a function of the measured pressure. In addition, it has a single built-in relay that is controlled by a user-adjustable pressure set point. One pin on the interface connector is used (by connecting to the "low" of the input DC voltage) to enable the high voltage of the gauge. Another pin on the interface connector may be used (by connecting to the "low" of the input DC voltage) to disable operation of the setpoint relay.

The electronics can be removed from the actual "gauge tube" to allow for baking (for this gauge, limited to ~150 C by the typical seal used with the KF flange).

Full specifications are available from MKS Instruments, as is a .PDF version of the manual. Should you have any difficulty locating that information, then please contact us; we may be able to help.
  • inverted magnetron cold cathode ionization gauge transducer
  • Series 903
  • part number 109030004
  • KF-25 flange
  • measuring range 3.0 x 10-10 Torr to 5.0 x 10-3 Torr
  • setpoint range 1.0 x 10-9 Torr to 1.0 x 10-3 Torr
  • one relay set point
  • power required: 14 to 30 VDC, 3 W maximum
  • analog output: 1.5 to 8.7 VDC
  • LED indicators for power, high voltage, and setpoint
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