GAS-DISCHARGE TRANSM IT-RECEIVE SWITCH 91 



Bell Telephone Company, while at the Bell Laboratories, was responsible 

 for the construction of test equipment and for most of the recovery time 

 measurements reported in this paper. At various periods during the de- 

 velopment work Messrs. A. B. Crawford, V. C. Rideout, G. M. Eberhardt 

 and J. P. Schafer were closely associated with the measurement of the system 

 performance of TR tubes. Mr. R. M. Purinton of the Bureau of Ships de- 

 serves much credit for his encouragement and assistance in the standardiza- 

 tion program which led to the adoption of the 721A and 724B tube designs 

 b}^ all manufacturers. The Thermionics Branch of the Evans Signal Labora- 

 tory provided the bulk of the electrical standardization, calibration and 

 engineering service associated with these tubes and assisted in the develop- 

 ment of improved test methods. The magnificent production job done by 

 the Western Electric Company and by other manufacturers, particularly 

 by the Sylvania Electric Products Inc. in making these tubes available to 

 the armed services also deserves mention. Perhaps the final mention should 

 go to the many circuit design engineers both within the Bell Laboratories 

 and elsewhere who handled the many difficult problems relating to the design 

 and use of TR cavities in actual radar systems. 



APPENDIX A 



Analysis of the Idealized TR Box 

 Schelkunoff has shown* that the impedance of a resonant cavity can be 

 represented in terms of its resonant frequencies as 



Z = Z -. —^ r (1) 



or in the vicinity of any single resonance as 



Z = Z,-\- -. ^ . (2) 



. / W _ (Jin\ _| J_ 



^W 0,)^ Qn 



Under most conditions the Zi term is negligibly small. We are therefore 

 justified in thinking of the generalized resonant cavity used as a TR switch 

 as a shunt resonant circuit to which are coupled input and output circuits. 

 For the moment we will consider (1) that these external circuits are resistive 

 only, (2) that the Zi in equation (2) is zero; and (3) we will restrict the analy- 

 sis to the in tune condition. 



When the cavity is excited by energy supplied from the input circuit 

 there exists in the cavity a certain amount of reactive power which will be 



* S. A. Schelkunoff, "Representation of Impedance Functions in Terms of Resonant 

 Frequencies," Froc. I.R.E., vol. 32, pp. 83-90, February (1944). 



