ULTRA-HIGH-FREQUENCY POWER AMPLIFIER 17 



TABLE I 

 Operating Characteristics and Constants of the Double Pentode Tube 



Filament current (each side) 5.0 amperes 



Filament potential (each side) 1.5 volts 



Rated anode dissipation (each anode) 15 watts 



Rated screen dissipation (each side) 5 watts 



At anode and screen potentials of 500 volts and anode current of 

 0.030 ampere — characteristics of each side 



Transconductance 1250 micromhos 



Anode resistance 200,000 ohms 



Normal control grid potential —45 volts 



Inlerelectrode capacitances {when properly mounted) 



Direct control grid to control grid 0.02 micromicrofarad 



Direct plate to plate 0.06 micromicrofarad 



Total control grid to ground (each side) 3.8 micromicrofarads 



Total plate to ground (each side) 3.0 micromicrofarads 



Control grid to plate (each side) 0.01 micromicrofarad 



Lead inductances 



Total grid to grid 0.07 microhenry 



Total plate to plate 0.08 microhenry 



Rating as class A amplifier 



Maximum direct plate potential 500 volts 



Maximum direct screen potential 500 volts 



Maximum continuous plate dissipation (each) 15 watts 



Maximum continuous screen dissipation (total) 10 watts 



Maximum output at 150 megacycles with distortion 



down 40 decibels 1 watt 



Nominal stage gain at 150 megacycles 20 decibels 



Nominal control grid potential —45 volts 



Rating as class B amplifier 



Maximum direct plate potential 500 volts 



Maximum direct screen potential 500 volts 



Maximum space current (total) 150 milliamperes 



Maximum continuous plate dissipation (each) 15 watts 



Maximum continuous screen dissipation (total) 10 watts 



Maximum output at 150 megacycles 10 watts 



electrode capacitances are low they have not been reduced in propor- 

 tion to the reduction in operating wave length. The more important 

 feature is the reduction of the lead inductances. Tabulation of the 

 value of these inductances represents a departure from the conven- 

 tional practice and is made desirable by their relative importance. 



A feature of the design not directly measurable under actual operat- 

 ing conditions but nevertheless responsible for some of the improve- 

 ment over the more conventional designs is the reduction of an auxil- 

 iary dielectric material and the attending dielectric losses that occur at 

 ultra-high frequencies. 



The usual static characteristics given in Figs. 6 and 7 are seen to 

 resemble those of the conventional pentode. For a tube which is to be 

 used at ultra-high frequencies, certain other characteristics have a 

 much greater significance. One of the most important of these is the 



