568 



BELL SYSTEM TECHNICAL JOURNAL 



permits the oscillator to be coupled to a fifty ohm coaxial cable. The 

 center conductor of the tube output line projects into the split chuck, 

 while contact is made to the outer conductor of the tube output line by the 

 spring contact fingers F. The coupling unit can be mounted in a standard 

 octal socket so that the tube can be coupled simultaneously to the power 

 supplies and the high frequency circuit by a simple plug in operation. It 

 is frequently desirable to insulate the outer conductor of the oscillator from 



Fig. 67. — Metal reflex oscillator with enclosed resonator designed for operation from 

 3400 to 3960 mc/s. 



^TO FIT TYPE"N" POLYSTYRENE 

 /( FITTINGS INSULATOR 



CHUCK FOR INNER 

 COAXIAL CONDUCTOR 



/ , CONTACT TO OUTER 



■ ^^^' ■ ' ( ' ' ' ' | \ / COAXIAL CONDUCTOR 



Fig. 68. — A transducer for connecting the output lead of the 2K29 to a 50 ohm cable. 



the line for direct voltages while maintaining the high frequency contact. 

 This can be accomplished with either an insulating sleeve of low capacitance 

 or a modification of the design which incorporates a high frequency trap 

 in the outer conductor. In some instances it is necessary to insulate the 

 center conductor of the tube from the line for direct voltages. This caji be 

 done with a concentric condenser. The characteristic impedance of the 

 section of the coupler may be made the same as that of the line by main- 

 taining the proper ratio of the diameters of the condenser and the outer 



