Improvements in high frequency pentodes

摘要

490,566. Thermionic valves. M-O VALVE CO., Ltd., BELL, J., and BOYLAND, D. A. June 3, 1937, No. 15421. [Class 39 (i)] In high - frequency pentodes, more especially those adapted to dissipate more than 100 watts, a shielding member 10 is interposed between the leads 12 to the suppressor grid 13 and the leads to the control grid 8. The shielding member may be solid, of fine mesh gauze, or a cage of wires, and is preferably a continuation of the screen grid 9 ; it is preferably continued outside the envelope to the points on the external circuit to which the control and suppressor grid leads are connected. In the embodiment shown, the anode 1 forms part of the envelope, the remainder of which is formed by a glass member 2 having an inverted foot-tube 3 closed by a seal 4, through which pass the leads 5 to the filament cathode 6, and also the lead 7 to the control grid. The lead to the helical wire screen grid 9 is a cage of wires 10 passing through the bottom of the foot-tube to a terminal 11, and acting as the shield between the control grid lead 7 and the lead 12 consisting of a number of wires to the suppressor grid which is also a cage of wires. The wires 12 pass through a ring seal to a ring 14 carrying terminals 15.