 d:	diameter of display
 l:	length of tube
 Uh:	heater voltage
 Ih:	heater current
 Ug1:	first grid voltage (Wehnelt-cylinder)
 Ua1:	first anode voltage
 Ua2:	second anode voltage
 Ua3:	third anode voltage
 D1-2:	deflection sensetivity (X)
 D3-4:	deflection sensetivity (Y)
