THE L3 SYSTEM — AMPLIFIEKS 



889 



Table II — Power Requijiements of Amplifier Unit 



6.3 volts (grounded) 1.5 amperes 



6.3 volts (190v off ground) 0.45 amperes 



+ 100 volts regulated 0.5 milliamps 



+ 190 volts 68 milliamps 



+315 volts 41 milliamps 



with internal helical springs mounted in such a manner that each turn 

 of the spring makes contact with both the glass tube envelope and with 

 the copper tube as shown in Fig. 6. Thus each turn of the spring provides 

 two metallic heat conducting paths to carry away the heat from the tube 

 envelope. A total of 480 conducting paths are provided for each of the 

 large tubes used in the output amplifier by the use of these springs. 

 Good contact is made between the copper tubes and the chassis, so that 

 heat generated within the vacuum tube is efficiently conducted through 

 metallic paths to the copper chassis of the amplifier. In order not to 

 raise the temperature of the chassis and consequently the temperature 

 of the circuit components, large ribs are provided in the housing, with 

 which the chassis make intimate contact. A continuous metallic con- 



GLASS VACUUM 

 TUBE ENVELOPE 



RADIATING 

 SURFACE 



Fig. 6 — Heat conducting tube shield. 



