NEW TRANSMISSION MEASURING SYSTEMS 9 



number over the circuit to be testedJ The testing power is cut off 

 at the sending end when the connection is broken at the receiving end. 

 Tests can be made in the same manner from private branch exchanges 

 and subscribers' stations without a charge being registered against 

 the subscriber. 





Fig. 6 — Small receiving set as used to measure the transmission loss of a sub- 

 scriber's line. The 1000-cycle generator has been connected to the central office end 

 of the line by calling a designated number. When the telephone instrument has been 

 replaced on the mounting, the meter in the measuring set will read the line loss. 



The receiving set shown in Fig. 4 is based on the electrical circuit 

 of Fig. 1. It has a transmission range of 20 db, and is provided with 

 all the jacks and facilities required for testing cord circuits, trunks and 

 central office equipment. A still smaller and less expensive receiving 

 set of a similar type having a 10 db range is shown in Fig. 6. It is 

 extremely portable and light and is useful for work where the limited 



