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BEl.I. SYSTEM TECHNICAL JOURNAL 



Fig. 12 is obtained. The stiffness of the reactances of arms Za and Zh 

 depends principally on the branches numbered 1, 2, 5 and 6. Each of 

 these branches may he combined with a j)ortion of C3 or C4 and replaced 

 with a crystal. 



One other restriction must be' 'overcome before crystals can be used. 

 Inductances Li and Lo are in the order of 0.7 henry while Z-5 and Le are in 

 the order of 5000 henries, both inductance values being impractical for 

 crystals. Two three-winding repeating coils are used to transform these 

 inductances to values that may be provided by crystals. The two bal- 

 anced windings of one repeating coil replace arms Zb of Fig. 12(a), the third 

 winding being connected to a reactance arm of the form of Fig. 12(c). 



OUTPUT 



Fig. 14 — Schematic of carrier-frequency equalizer. 



The other repeating coil is similarly used for arms Za , the inductance Lg 

 being provided by the repeating coil. The repeating coils unavoidably 

 introduce parasitic inductances, a small one in series with Za and a larger 

 one in parallel with Zb, the effects of which are made negligible by the 

 addition of a capacitance in parallel with Zb ■ 



Dissipation in the elements of the carrier-frequency equalizer is taken 

 into account by making use of the equivalence of Fig. 13, in which (a) 

 represents the non-dissipmtive equalizer in tandem with a pad and (b) a 

 structure similar to the non-dissipative structure but with resistances added 

 to its arms, as shown by (c) and (d). The dissipation in each coil, con- 

 denser or crystal can be associated to a close degree of appro.ximation with 



