INSTRUMENTS FOR THE NEW TELEPHONE SETS 



339 



with the new combined set in the photograph, Fig. 1, and in cross- 

 section on Fig. 2. 



In designing this handset every effort has been made to obtain the 

 maximum degree of simpHcity consistent with the electrical require- 

 ments involved and at the same time to secure an attractive design 

 which harmonizes with the other station apparatus on the subscriber's 

 premises. Only three phenol plastic parts are employed; namely, the 



Fig. 1 — Handset and desk stand equipped with the new instruments. 



handle and the transmitter and receiver caps. In designing these 

 parts particular attention has been paid to providing adequate cross- 

 sections at the points of maximum stress and to distributing the 

 weight so as to reduce to a minimum the breaking moments which are 

 developed when the handset is dropped. The transmitter and re- 

 ceiver caps serve the dual purpose of holding the units in place and 

 providing mechanical protection. In addition they thoroughly insu- 

 late the user from all the metal parts which are included in the electrical 

 circuit. Both caps have smooth surfaces which can be readily cleaned. 

 As will be pointed out later, the grid of the receiver cap also has a 

 transmission function and plays an important part in determining the 

 response in the upper frequency range. Spring contacts are provided 

 to facilitate the assembly of the units in the handle. This operation 

 is further facilitated by the fact that specific alignment of the units 



