THE L3 SYSTEM — EQUALIZATION AND REGULATION 



855 



the number of the term. If all derivatives are finite the coefficients will 

 decrease exponentially. This last case is believed to describe the con- 

 vergence for at least most of the L3 system shapes. Thus for the high 

 order terms that require little range it is possible to reduce the flat loss 

 of the networks. 



In order to reduce the flat loss without changes in the 75-ohm im- 

 pedance level of the phase sections or in the dual adjustable resistors, 

 pads are inserted between the resistance T and the all-pass sections. 

 In this manner the loss could be reduced to 2.2 db for d=0.5 db range if 

 it were not for the dissipation in the all-pass sections. This dissipation 

 is due to the coils and increases with frequency. It tends to produce a 

 reduced cosine amplitude in the high frequency part of the band. To 

 correct this effect, the pad mentioned above is actually made an equalizer 

 section whose loss change with frequency corrects for the dissipation 

 in the coils thereby yielding cosine amplitudes independent of frequency. 

 The price of this is an increase of the flat loss to 3.4 db for ±0.5 db 

 range. The circuit of the term 10 network is shown on Fig. 10. The range 



Fig. 9 — Range required for various cosine terms due to expected manufactur- 

 ing variations of eight critical elements. The magnitudes are based on RSS addi- 

 tion in 25 repeaters. 



