FLUCTUATION NOISE IN VACUUM TUBES 



649 



TABLE III 

 Western Electric No. 262A Tube 



wide operating range, but is closely dependent on the plate current as 

 affected by the control and screen grid voltages. Table IV contains 

 the operating conditions and noise data for this tube. 



Noise measurements were also made on the No. 259B tube with its 

 control grid floating at equilibrium potential. Using the operating 

 voltages specified above, the noise level was about 20 db higher than 

 those given in Table IV. The level can be greatly reduced by oper- 

 ating the tube at a lower cathode temperature and with lower screen 



TABLE IV 

 Western Electric No. 259B Tube 



