INDUCTIVE LOADING FOR TELEPHONE FACILITIES 



467 



Altogether, this was a remarkable achievement of the apparatus develop- 

 ment and factory engineers. 



The new coils had code designations 10 digits higher than those of the 

 coils which they superseded, beginning on a quantity production basis dur- 

 ing 1942. The very extensively used 632 coil became widely known as the 

 ''wedding-ring" coil. It appears as Coil J in the headpiece. 



Fig. 17 — Case size reduction 100-coil complements 88 mh. coils. At left: Lead sleeve 

 case containing No. 622, molybdenum-permalloy core, coils. At right: Welded steel case 

 containing No. 632 coils having Formex insulated windings on molybdenum-permalloy 



To provide the most economical potting arrangements for the new coils 

 an entirely new series of loading coil cases was developed. 



The economies that have resulted from these coil and case developments 

 in the post-war period are large relative to the development cost, and are 

 large in the aggregate, even though the savings per potted coil are small. 

 The current demand for this series of coils greatly exceeds the aggregate 

 demand for all other types of loading coils. 



At this point it is of interest to present Fig. 18, which illustrates the pro- 



