Compare Model Drawings, CAD & Specs Compatible with Interface Relays Units Electrical Plug Availability Price
307501-000-M3 274 Ionization Gauge No 0 mbar Europe 220 VAC $1,925
307501-000-M4 274 Ionization Gauge No 0 mbar UK 240 VAC $1,925
307501-000-T1 274 Ionization Gauge No 0 Torr North America & Japan 120 VAC $1,925
307501-010-P1 274 Ionization and 275 Convectron Gauges No 0 Pascal North America & Japan 120 VAC $2,450
307501-A00-T1 274 Ionization Gauge RS232 0 Torr North America & Japan 120 VAC $2,375
307501-B0A-T1 274 Ionization Gauge RS485 2 Torr North America & Japan 120 VAC $2,675
307501-B1B-T1 274 Ionization and 275 Convectron Gauges RS485 6 Torr North America & Japan 120 VAC $3,475
307502-000-M3 274 Ionization Gauge No 0 mbar Europe 220 VAC $1,975
307507-000-P1 274 Ionization Gauge No 0 Pascal North America & Japan 120 VAC $2,300
307507-C10-T3 274 Ionization and 275 Convectron Gauges IEEE 488 0 Torr Europe 220 VAC $3,375
307507-D1B-T1 274 Ionization and 275 Convectron Gauges Analog Output 6 Torr North America & Japan 120 VAC $3,600
307508-000-T1 274 Ionization Gauge No 6 Torr North America & Japan 120 VAC $2,375


  • Type
    Bayard-Alpert Gauge Controller
  • Lower Measurement Limit
    1 x 10-10 Torr with 10 mA emission and tube sensitivity of 10/Torr
  • Upper Measurement Limit
    0.1 Torr with 0.1 mA emission and tube sensitivity of 10/Torr
  • Pressure Range
    7 decades within above limits for given emission setting and tube sensitivity
  • Display
    Digital (green LED)
  • Display Update Rate
    0.5 second typical
  • Units
    Torr, mbar, Pascal (user-selectable)
  • Power Requirements
    100/115/230 ±10% VAC (user-specified), 250 watts, 50 or 60 Hz
  • Communication Protocol
    Optional: IEEE-488 (parallel) RS-232 or RS-485 (serial)
  • Analog Output
    Logarithmic: 1 V per decade, 0-10 VDC
  • Emission Current
    Controlled, adjustable from 0.01 to 10.0 mA
  • Degas
    Electron Bombardment: 10-40 watts adjustable
    I2R: 8 V nominal, (fixed) 80 W maximum
  • Operating Temperature
    40°C maximum


Accurate Pressure Measurement

  • Increased pressure measurement accuracy by controlling emission current, tube temperature is stabilized, thereby stabilizing thermal transpiration and its effects, outgassing, and wall charges.
  • For extended pressure range measurement capability and/or prolonged tube life, emission current can be adjusted.
  • Studies have shown Bayard-Alpert type gauges to be 30 to 40% inaccurate. Although the 307 VGC will very accurately measure the ion current, these inaccuracies are inherent in the design of the B-A gauge and cannot be consistently compensated for by any IG controller.
  • Refer to the Granville-Phillips® Series 370 Stabil-Ion system when better accuracy is required.
  • High quality shielded cables are used between the control unit and power supply, and to the gauge tubes. To help prevent electrical disturbance, RF filters are used at critical junctions.
  • Less circuit drift and greater pressure measurement accuracy are achieved with a lower temperature rise in the instrumentation enclosure by removing the power supply from the vicinity of the control unit.

Excellent Process Control

  • Enhanced process control with up to 6 set points including 2 on the ionization gauge and 2 on each of two Convectron or thermocouple gauges or capacitance manometer.
  • Available Convectron or thermocouple gauge capability allows for automatic turn-on of ionization gauge at pre-selected pressure.
  • Set points can be overridden manually to facilitate system set-up and maintenance.
  • Set point polarity can be user-selected such that relays are activated for pressures either above or below programmed set point.
  • Status of set points indicated on front panel which can be identified with user-customized labels.
  • Convectron Gauge lower limit of 1 x 10-4 Torr, achieved with careful individual zeroing at vacuum, makes this gauge more suitable to control processes such as sputtering in the 1 x 10-3 Torr range.

Improved Economy

  • Easy customization design allows purchase of only those modules needed for current application.
  • Easy field upgrade to more complex capabilities at a reasonable cost.
  • Saves valuable panel space with small size half-rack width.
  • No extra space required for ventilation since low power dissipation of control unit permits mounting against other instruments.
  • Minimal downtime due to ability to locate failed circuits with the help of fault lights. Boards are easy to inventory since each board contains primarily those circuits relevant to its capability. Easily replaceable modules allow quick in-field repair.

Increased Reliability

  • Supported by MKS' five-year limited warranty against defects in materials and workmanship.
  • Power-outage protection with all settings non-volatile so that programmed information is saved in case of power loss or surges. Process control action has selectable relay status so that power-off condition is user-definable. IGs will return to “on” when power recovers, if automatic IG on/off control is in use.
  • Damage protection is designed-in. The controller is protected from short circuits in the gauge tube by special circuitry. The gauge protected from overpressure. Arcs during degas are prevented since plasma build-up causes the control unit to shut down without damage.

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