TRANSATLANTIC RADIO TELEPHONY 



123 



Below are the smaller amplifying stages. The power supply board is 

 shown in the center of the photograph. 



Fig. 3 is a side view of the 15-kw. amplifier unit. The face of the 

 panel from which the control handles protrude is on the left. Mounted 

 in the cage behind the front panel are two water-jackets for accom- 

 modating the water-cooled tubes, also a coiled hose for increasing the 

 electrical resistance of the water supply circuit (the water-cooled 

 anodes of the tubes being operated above ground potential). 



The final amplifier of 150-kw. capacity is shown in Fig. 4. It 

 comprises two units each of 75 kw. Each unit contains 10 water 

 cooled tubes which can be seen mounted in their water jackets. 

 To the right of these units is located the 200-kw. rectifier unit shown 

 in Fig. 5. The unit contains actually 12 tubes, there being two tubes 



Fig. 4 



for each of the six half waves. The pancake coils on the top of the 

 rack are protecting choke coils to guard the transformer secondary 

 winding against steep wave fronts in case of tube failure. 



From the above description it will be understood that the trans- 

 mitting system is one in which the useful side-band is first developed 



