464 BELL SYSTEM TECHNICAL JOURNAL 



the properties of mixers in terms of linear-network theory. In Part I the 

 network equations are derived from the fundamental properties of nonUnear 

 resistive elements. Part II contains a resume of the appropriate formulas 

 of linear-network theory. In Part III the network theory is applied, first 

 to the case of simple nonlinear resistances, and next to the more general 

 case where the nonlinear resistance is embedded in a network of parasitic 

 resistive and reactive passive-impedance elements. In Part IV application 

 of the previous results is made to the measurement of performance properties. 

 The "impedance" and the "incremental" methods of measuring loss are 

 contrasted, and it is shown that the actual loss is given by the incremental 

 method when certain special precautions are taken, while the impedance 

 method is in itself incomplete. 



A Figure of Merit for Electron-Concentrating Systems.'' J. R. Pierce. 

 Electron-concentrating systems are subject to certain limitations because 

 of the thermal velocities of electrons leaving the cathode. A figure of merit 

 is proposed for measuring the goodness of a device in this respect. This 

 figure of merit is the ratio of the area of the aperture which, in an ideal 

 system with the same important parameters as the actual system, would 

 pass a given fraction of the cathode current to the area of the aperture which 

 in the actual system does pass this fraction of the cathode current. Ex- 

 pressions are given for evaluating this figure of merit. 



A 60-KilowaU High-Frequency Transoceanic-Radiotelephone Amplifier.^ 

 C. F. P. Rose. Here is described a high-frequency radio amplifier recently 

 developed for the transoceanic-telephone facilities of the Bell System at 

 Lawrenceville, New Jersey. In general, the ampliiier is capable of delivering 

 60 kilowatts of peak envelope power when excited from a 2-kilowatt radio- 

 frequency source. It is designed to operate as a "class B" amplifier for 

 transmitting either single-channel double-sideband or twin-channel single- 

 sideband types of transmission. Features are described which permit 

 rapid frequency-changing technique from any preassigned frequency to 

 another lying anywhere within the spectrum of 4.5 to 22 megacycles. 



Some Notes on the Design of Electron Guns.^ A. L. Samuel. A method is 

 outlined for the design of electron guns based on the simple theory first 

 published by J. R. Pierce. This method assumes that the electrons are 

 moving in a beam according to a known solution of the space-charge equa- 

 tion, and requires that electrodes exterior to the region of space charge be 

 shaped so as to match the boundary conditions at the edge of the beam. 

 An electrolytic tank method is used to obtain solutions for cases which are 

 not amenable to direct calculation. Attention is given to some of the 



^ Proc. LR.E., July 1945. 

 8 Proc. LR.E., October 1945. 

 » Proc. LR.E., April 1945. 



