600 



BELL SYSTEM TECHNICAL JOURNAL 



Fig. 90. The electron optical system consists of a concave cathode, a 

 cylindrical beam electrode, and a grid concave towards the cathode. This 

 produces an electron beam which converges into a conical nose and through 

 the cavity grids to the repeller space. The repeller, which returns the beam 

 across the gap, is rigidly held in a mica supported in a cylindrical housing 

 connected to a diaphragm which serves as one wall of the resonator. The 



^^ 



JiS 



f = 23,984 MEGACYCLES 

 PER SECOND 



Fig. 92. — Performance diagram for the 2K,S() at the mid-hand frequencj-. 



cylindrical housing is connected to a thermal tuning mechanism consisting 

 of a simple framed structure in the shape of a right triangle. The base of 

 the triangle is a heavy piece of metal brazed to the cavity block and a bleeder 

 shoe which in turn is brazed to the bulb. One leg of the triangle can be 

 heated by electron bombardment controlled, as in the 2K45, by a negative 

 grid. The other leg is heated only by conduction. Since both legs are 

 made from the same material, general heating of the structure will produce 



