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power stage of such a set is shown in Fig. 3. The units marked 1,2, 

 and 3 are the water jackets for three of the six double-ended, 10-kw. 

 tubes, the other three being on the other side of the mounting. The 

 circuit is of the push-pull type. 



Fig. 3 — Short-wave radiotelephone transmitting center of the American Tele- 

 phone and Telegraph Company, Lawrenceville, X. J. Six lO-kw. tubes used in 

 one of the output stages of a transmitting set. Coupling coils on right, monitoring 

 amplifier boxes at lower right. 



The radio receivers employed in the United States are built so as 

 to have low intrinsic noise and sufficient gain to enable very small 

 field strengths, of the order of 1 nv. per m., to be detected and raised 

 to the required telephone speech level. They are equipped with auto- 



