552 BELL SYSTEM TECHNICAL JOURNAL 



mw output when driven with 200 mw of beating oscillator power. A 

 bandwidth of twenty megacycles was readily obtained. 



As amplifiers at 4060 mc, the average gain of 60 tubes was 9 db, the 

 average bandwidth of 34 tubes was 103 mc to the half power points, the 

 average noise figure of 35 tubes was 18.08 db and the average power out- 

 put (for 3 db gain) was 455 mw for 25 tubes. Operating the tubes in 

 cascade produced an amplifier which had less distortion of pulse shape 

 than an earlier amplifier which used the 402-A velocity variation tube. 

 A ten-stage amplifier has been assembled and tested, yielding 90 db gain, 

 a noise figure (with selected tubes) of 15.96 db and a bandwidth of 44 

 mc to the 0.1 db points. 



These data are for early experimental models of the tube and it is 

 likely that subsequent alterations may improve the performance in the 

 production models. 



Acknowledgments 



The work described in this paper took place at the Holmdel Radio 

 Research Laboratories. Mr. Bowen, with the able assistance of Mr. E.L. 

 Chinnock, was active in pursuing the problems connected with the ampli- 

 fier circuits. Mr. R. H. Brandt helpedwith the work in connection with 

 the modulator circuits and many others were helpful in designing and 

 constructing the circuits and facilities for testing. 



References 



1. "Microwave Repeater Research," H. T. Friis, B. S. T. J., Vol. 27, pp. 183-246, April 



1948. 



2. "A Microwave Triode for Radio Relay," J. A. Morton, Bell Labs. Record, Vol. 27, ^5, 



May 1949. 



3. "Microwave Converters," C. F. Edwards, Proc. L R. E., Vol. 35, pp. 1181-1191, Nov. 



1947. 



4. "Maximally-Flat Filters in Wave Guide," W. VV. Mumford, B. S. T. J., Vol. 27, pp. 



684-713, Oct. 1948. 



5. "Testing Repeaters with Circulated Pulses," A. C. Beck and D. H. Ring, Proc. /. R.E., 



Vol. 35, pp. 1226-1230, November 1947. 



6. "A Broad-Band Microwave Noise Source," W. W. Mumford, B. S. T. /., Vol. 28, pp. 



608-618, October 1949. 



7. "Electron Admittances of Parallel-Plane Electron Tubes at 4000 Megacycles," Sloan 



D. Robertson, B. S. T.J., Vol. 28, pp. 619-646, October 1949. 



8. "Design Factors of the Bell Telephone Laboratories 1553 Triode," J. A. Morton and 



R. M. Ryder, B. S. T. J., Vol. 29, f^4, pp. 496-530, Oct. 1950. 



