 Uh:	heater voltage
 Ih:	heater current
 Ua:	anode voltage
 Ia:	anode current
 Ug5:	grid5 voltage
 Ug4:	grid4 voltage
 Ig4:	grid4 current
 Ug3:	grid3 voltage
 Ig3:	grid3 current
 Ug2:	grid2 voltage
 Ig2:	grid2 current
 Ug1:	grid1 voltage
 Rg1m:	maximal grid1 resistor
 S:	mutual conductance
 Gain:	gain coefficient
 Rint:	internal resistance
 Ra:	optimal load resistance
 Pout:	output power
 Pa:	anode power
