276 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1953 



Fig. 4 

 filters. 



The 1509 type adjustable ferrite inductor for Type-0 carrier system 



using the value 0.01 for d. Thus the "geometric Q", that which would 

 obtain were it not for the distributed capacitance, is about 330. 



The 1509 type inductor, shown in Fig. 4, was designed for use in the 

 type-0 carrier system.^ It has a volume of 1.4 cubic inches, 35 times 

 that of the small coil discussed above. From the standpoint of dc re- 

 sistance and core loss alone, (7) indicates that the dissipation factor 

 should be 



A = 3^3 (0.0030) = 0.00092, 



or that the Q should be greater than 1000. 



In order to keep the capacitance to the same order as that of the small 

 coil, and to use stranded wire to avoid excessive ac loss, the winding 

 efficiency, ky, , had to be reduced from 0.4 to 0.13. The effect of this on 

 dissipation can be shown from (17), remembering that k^ varies inversely 



fc. 



Do 



(Sh) 



1/2 



1.73 



Do = (1.73) (0.0092) 



0.00159. 



Thus, the Q (still neglecting the effect of the 10 mmf distributed capaci- 

 tance that remains after reducing the winding efficiency) should be 630. 



