TRANSATLANTIC TELEPHONY 



173 



Fig. 6 shows the large vacuum tubes used in the last stage of the 

 Rocky Point long wave radio transmitter. As many as 35 such tubes 

 are employed in parallel capable of putting into the antenna something 



Fig. 6 — Showing last power stage 



over 200 killowatts which, as already noted, is worth something over 

 six times this amount in the form of ordinary radio transmission. 



This is the only picture I shall show of any of the apparatus involved 

 in this work although such apparatus represents, of course, a tremen- 

 dous amount of fundamental investigation and development and 

 design. In a picture of apparatus, however, you can see little but 

 assembly of cases and wiring and occasional vacuum tubes, and this 

 gives you no adequate idea of what is going on electrically inside of the 

 devices. An interesting feature of the transmitting apparatus in this 

 system is that in the process of suppressing the carrier and stripping 

 off one of the side bands, a double frequency transformation is required. 

 For example, a 1,000-cycle tone coming into the station appears first 



