Vacuum tubes were previously in use. Mix by years of production.
Technical characteristics and electrical parameters of the 6P14P lamp:
Glow voltage6.3 u00b1 0.6 VGlow current760 u00b1 60 mAAnode voltage rated (constant)250 VAnode Voltage Limit300 VAnode current48 u00b1 8 mACathode Current Limit65 mAThe grid voltage is the second rated (constant)250 VSecond grid voltage limit (constant)300 VSecond grid currentno more than 7 mAMaximum power dissipated by the anode14 wattsThe power dissipated by the second grid2 wattsVoltage between cathode and heater extreme (constant)100 VSteepness characteristics11.3 mA / VGain in triode switchingabout 20Internal resistance30 kOhmResistance in the cathode circuit for auto bias120 ohmInput capacityabout 11 pFOutput capacityabout 7 pFCapacity through passageabout 0.2 pFDecorminiature glass