A Medium Power Traveling-Wave Tube 

 for 6,000-Mc Radio Relay 



By J. P. LAICO, H. L. McDOWELL and C. R. MOSTER 



(Manuscript received May 15, 1956) 



This paper discusses a traveling-wave amplifier which gives 30 dh of gain 

 at 5 watts output in the 5,925- to 6,425-nic common carrier hand. A descrip- 

 tion of the tube and detailed performance data are given. 



TABLE OF CONTENTS Page 



I. Introduction 1285 



II. Design Considerations 1288 



III. Description of the Tube 1291 



3.1 General Description 1291 



3.2 Tlie Electron Gun and Electron Beam Focusing 1295 



3.3 The Helix 1302 



3.4 The Collector 1311 



IV. Performance Characteristics 1314 



4.1 Method of Approach 1314 



4.2 Operation Under Nominal Conditions 1315 



4.3 Operation Over an Extended Range 1325 



4.4 Noise Performance 1333 



4.5 Intermodulation 1336 



V. Life Tests 1342 



VI. Acknowledgements 1343 



I. INTRODUCTION 



During the past ten years traveling-wave tubes have received con- 

 siderable attention in vacuum tube laboratories, both in this country 

 and abroad. So far their use in operating systems has been somewhat 

 limited, the most notable exceptions being in radio relay service in France, 

 Great Britain, and Japan. However, it appears that sufficient progress 

 in both tube and system design has been made so that traveling-wave 

 tubes may see widespread application in the near future. 



This paper describes an experimental helix type traveling-wave tube 

 representative of a class which may see extensive use as a power amplifier 

 in radio relay systems. The tube is designated as the Bell Laboratories 

 type MI789. Stated briefly, the performance characteristics under 

 nominal operating conditions arc: 



1285 



