| 摘要 |
913,613. Valve oscillating circuits. RADYNE Ltd. May 9, 1961 [May 13, 1960], No. 17037/60. Class 40 (6). A generator for radio-frequency heating comprises a pair of oscillator valves operating in push-pull and having a cavity resonator as tank circuit, providing an output for an incompletely screened work circuit. The arrangement is stated to provide a stable oscillator giving a reduced output at harmonic frequencies. The tank circuit comprises a cavity resonator having a cylindrical wall 12, Fig. 1, and flat end-plates 14, 16, there being an inner capacity unit comprising concentric cylinders 18, 20 alternate ones of which are connected to opposite endplates. To each end plate is affixed a screened compartment 22 housing one of the oscillator valves 24, the anodes of which are connected to taps 30, 32 on the innermost cylinders 20, 18 respectively, adjustment of which enables the oscillator to be balanced. The grids are connected via blocking capacitors to coupling loops 36 in the cavity, and via R.F. chokes 38 to tungsten filament lamps 40, the resistance of which increases with increase in grid current. The anodes of the valves are fed via R.F. chokes 26 and the anode feed circuits may include overload trips; blowers 48 are provided. The work electrode 46 is connected via series variable capacitor 44 to a small coupling loop 42 in the cavity. In another embodiment, which is a modification of the arrangement disclosed in Specification 877,014, the cavity resonator comprises cylindrical wall 12, Fig. 2, and end-plates 14, 16 to which are attached inner cylindrical members 50, 51 respectively. Members 50, 51 form with an enclosed cylindrical member 52 a pair of capacitors seriesconnected across the cavity. The push-pull oscillator valves 53, 54 are located at either end of the inner cylinder 52, their anode terminals 55 being connected to this cylinder while the grid terminals 56 are connected via blocking capacitors to the end-plates 14, 16 respectively. One filament terminal 58 of each valve is coupled via a blocking capacitor to a corresponding pick-up loop 60 providing the driving voltage. Output is taken via a coupling loop 62. |
