SILICON CRYSTAL RECTIFIERS 7 



quency instrument rectifiers. They were also used to a relatively minor 

 extent in some of the early radar test equipment. Moreover, the avail- 

 ability of these devices and the knowledge of their properties as microwave 

 converters tended to focus attention on the potentialities of radar designs 

 employing crystal rectifiers in the receiver's frequency converter. Similarly, 

 the techniques established for preparation of the inserts tended to orient 

 subsequent manufacturing process developments. For example, the 

 methods now generally used for preparing silicon ingots, for cutting the 

 rectifying element from the ingot with diamond saws, and for forming the 



lO-i 



10-2 



10-3 



10-8 



10-6 



10-5 lO"'^ 



CURRENT IN AMPERES 



10-3 



10-2 



10-1 



Fig. 4 — Direct-current characteristics of silicon and iron pyrite rectifiers 

 fabricated as inserts, 1939. 



back contact to the rectifying element by electroplating procedures, are 

 still essentially similar to the techniques used for preparing the inserts in 

 1939. As a contribution to the defense research effort, this basic informa- 

 tion, with various samples and experimental assemblies, was made available 

 to governmental agencies for dissemination to authorized domestic and 

 foreign research establishments. 



Development of the Ceramic Type Cartridge Structure 



The block rectifier structure previously described was well adapted to 

 various laboratory needs because of its flexibility, but for large scale utiliza- 

 tion certain Umitations are evident. Not only was it necessan^- that the 

 parts be accurately machined, but also the adjustment of the rectifier in 



