| 摘要 |
1,220,469. Thermionic valves. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. 26 April, 1968 [27 April, 1967], No. 19865/68. Heading H1D. A screen grid tube has electrode supply conductors 1, 2, 3 in the form of coaxial cylinders connected to the cathode 5, control grid 6 and screen grid 7 respectively from the inside outwards, and the characteristic impedances Zg 1 k and Zg 2 g 1 of the lengths of coaxial line formed by the control grid and cathode supply conductors, and the control grid and screen grid supply conductors respectively, are selected such that the ratio obtains, where Cg 1 g 2 and Cg 1 k are respectively the pure electrode capacitances between the control grid and screen grid and between the control grid and cathode. This construction compensates for unwanted damping in the input and output circuit of an amplifier resulting from coupling between the output and input of the tube through the cathode lead inductance. The formulation of the ratio of impedances and electrode capacitances is given in detail, and if it is assumed that the effect of the cathode lead inductance lies solely within coaxial supply conductor 1 then the equality sign in the ratio holds; however since the connection of cathode to earth may also contain an inductive component this effect may be compensated by selecting the impedance ratio somewhat less than the capacitance ratio. |
