TRANSFORMER COUPLING CIRCUITS 



619 



were wound in the two grooves of the last spool type assemjjly in 

 such a manner as to maintain satisfactory balance for this type of 

 operation. Four adjustable condensers were added externally to these 

 transformers as shown in Figs. 8 and 9. The capacity of the con- 

 densers was adjustable so that the transmitted band could be located 

 anywhere between 50 and 150 kilocycles. 



^" 



44 45 46 



47 48 49 50 51 52 



FREQUENCY — KILOCYCLES 



Fig. 8 — Transmission characteristic of a triple transformer type of tuned circuit. 



Fig. 8 shows the circuit schematic and transmission characteristic 

 of the same transformer network at 50 kilocycles when operating from 

 a non-inductive resistance into the grid circuit of push-pull modulator 

 tubes. A step-up transformer was used between the resistance and 



