MAGNETRON AS GENERATOR OF CENTIMETER WAVES 



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Columbia University was undertaken to prepare for manufacture a variation 

 of a magnetron developed there. Prior to this, some work, primarily of an 

 exploratory nature had been done in our Laboratories. When it had been 

 demonstrated that scaling from the 10 cm. range yielded an efficient 3 cm. 

 magnetron, similar attempts were made in scaling to wavelengths of 1 to 2 

 cm. Magnetrons of such wavelengths, obtained by scaling from eight 



Fig. 75— A view i)f a cut-away 4J52 "packaged" magnetron (100 kw., 9375 nic/s) 

 which in internal details is efsentially like the 4J50 magnetron (280 kw., 9375 mc/s). 

 Of special interest are: the axial cathode construction including permendur end pieces 

 and radiative extension; the c}uarter wavelength transformer of H-shape cross section 

 (between the output resonator and the line wave guide); and the wave guide window con- 

 struction with associated chokes. 



resonator, 10 cm. models like the 706A-C, were unstrapped while others 

 were strapped with the early British type of strapping and with double ring 

 type strapping. Others were made by scaling from twelve resonator, 3 cm. 

 models and were strapped with both double and single ring straps. The 

 output circuits used were of the loop and coaxial type. 



Although some of these magnetrons were faulty, primarily in their output 

 circuits, the majority oscillated. One magnetron of the unstrapped eight 

 resonator variety, the most successful type, was operated over a consider- 



