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THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1953 



(5) Frequency at which these experiments are to be performed should 

 be in a microwave band where good waveguide components and measure- 

 ment techniques are available. 



These considerations have led to the adoption of an external cavity 

 type reflex klystron, the Sylvania 6BL6, as a vehicle for the experimental 

 studies to be described, and operation in the 3700-4200 mc band. 



4.1 Constructional Features of Experimental Tube and Circuit 



The 6BL6 is one of a group of Sylvania low-voltage reflex klystrons^" 

 designed for use with external cavity resonators. Electrical connection 

 to the interaction-gap grids is made through gold plated contact rings, 

 formed from the disc seals which pass through the glass. The top ring 

 is slightly smaller in diameter than the bottom ring, thereby permitting 

 the insertion of the tube without disturbance to the associated cavity. 

 Fig. 14 shows the external appearance of this tube and also contains a 

 view of the major components of the passive circuit with cutouts to 

 indicate the internal construction. 



SECONDARY Q 



TUNING 

 ADJUSTMENT 



SECONDARY 

 CAVITY 



RESISTANCE VANE 



COUPLING ADJUSTMENT 



BETWEEN PRIMARY AND 



SECONDARY CAVITY 



SHUTTER TO VARY . 

 OUTPUT COUPLING 



IRIS 

 OUTPUT 



Fig. 14 — An exporiinontal coupled resonator reflex klystron having a fixed 

 frequency primary cavity. 



