1010 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1952 



phase angle over the entire frequency range. The result is a direct-reading 

 bridge sho\m in Figs. 8 and 9 which has greatly facilitated the develop- 

 ment of inductors in the megacycle range. The accuracy for major 

 component varies from ±0.25 per cent at one megacycle up to ±1 

 per cent at five megacycles. 



TEN-MEGACYCLE ADMITTANCE BRIDGE 



De\^elopment of capacitoi's for the L3 coaxial system has recjuired a 

 new ten-megacycle admittance bridge. Intended especially for determin- 

 ing temperature coefficient and fre([uenc,y characteristics of small capa- 

 citors, the bridge is capable of measuring capacitance values up to 200 

 MM/^vith a precision of drO.Ol mm/, and a wide range of conductance values. 

 Unlike the other two bridges described which make grounded measure- 

 ments only, this bridge is arranged for direct and balanced-to-ground 

 measurements as well. This is accomplished by using the ratio-arm trans- 

 former already described in combination with a simple grounding circuit 

 using a three-position key, as shown in the bridge schematic of Fig. 10. 



® © "D" @ @ 



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Fig. 10 — Ten-megacycle admittance l)ridge with three-position key for shift- 

 ing ground to B for measuring direct admittance, to junction of CI and C2 for 

 balanced admittance, and to D for grounded admittance. Unknowns may be 

 connected from A to D or C to D. 



