GB691730A - Improvements in or relating to ionisation gauges - Google Patents

Abstract

691,730. Ionization gauges. MULLARD RADIO VALVE CO., Ltd. Feb. 29, 1962, No. 5377/52. Class 37. In a vacuum gauge of the ionization type in which a triode structure is open to-the vacuum to be measured and in which the grid is positive and the anode negative with respect to the filament, the filament current is controlled by a saturable reactor. The ionization gauge valve 1 comprises a filament 5, positive electrode 6, and negative electrode 6a. The filament 5 is connected in series with the secondary winding 7 of a transformer 8 and the controlled windings 10, 11 of a saturable reactor 12 through rectifiers 13, 14. A resistor 24 is connected between the junction of -the windings 10, 11 and the junction of the rectifiers 13, 14. The controlling windings 15, 16 of the saturable reactor 12 are connected in series between the anodes of a double triode valve 17, the cathodes of which are earthed through a bias resistor 18. The control grid 19 of one of the triode sections is connected to a stabilized voltage source, which is manually variable. The control grid 20 of the other section is connected ,to earth through a tgrid-leak 21 and to the junction of a pair of resistors 22, 23 connected across the filament 5. If the current between the filament 5 and electrode 6 of the valve 1 .alters, the potential of the control grid 20 also alters and causes a change in the current ,through the control windings 15, 16 so as to adjust the filament current to the correct value. This value of filament current to give a predetermined current in the valve 1 may also be obtained by manually adjusting the voltage on the grid 19 so as to set the equilibrium point of the system.