380 



THE WORLD '8 ADVANCE 



vided, which has efficiency far greater 

 than most receiving sets now available. 

 The set to be described is of the 

 popular "panel" style, in which all the 

 adjustments are placed upon the front 

 side of a cabinet containing the various 

 coils and other components. There is 

 provided an ordinary receiving trans- 

 former with taps, and in addition twelve 

 of the special couplers which will here- 

 after be known as "fixed" couplers. 

 Upon the front face of the cabinet there 

 is mounted, in addition to the tap switches 

 for the receiving tuner and the variable 

 condenser knobs, a special switch for cut- 

 ting in any one of the fixed couplers, 

 and also a compound switch for chang- 

 ing from the use of the receiving trans- 

 former to the fixed couplers. The switch 

 for connecting any one of the fixed 

 couplers is made double in order to in- 

 sure that when any one of the couplers 

 is in use there shall be absolutely no con- 

 nection to any other coupler, as such con- 

 nection might possibly set up oscillations 



in coils not intended to be used at the 

 particular time considered. In order to 

 accomplish this highly desirable sever- 

 ance of all connection with loreign cir- 

 cuits, switch points are provided for both 

 ends of both secondary and primary coils 

 of the fixed couplers. Finally, in order 

 to prevent production of induced cur- 

 rents in any of the fixed couplers while 

 one of them is in operation, the fixed 

 couplers are arranged parallel to each 

 other, this arrangement being devoid of 

 inductive connection. 



Referring now to the drawings, there 

 is provided in Fig. I a perspective view 

 of the completed instrument. In this 

 view the arrangement of switches and ad- 

 justments is clearly shown on the front 

 of the box, the handle for adjusting the 

 secondary of the receiving transformer 

 is shown on the right side of the same 

 and the binding posts for the apparatus 

 conveniently placed at the rear. The 

 secondary is controlled by turning the 

 knurled knob and the coupling by pull- 



The Improved Inductive Tuner as it Appears when Completed. 



