Voltage Pentode - Sharp Cutoff (single) ·Pentode
Indirectly heated high-impedance pentode with very high amplification factor and low grid-plate capacitance for high-gain small-signal amplification.
Indirectly heated oxide-cathode pentode with a metallised bulb connected to cathode, very high published plate resistance, and typical low-power amplifier operating data.
European 5-pin base
General specifications
Properties common to every published source and operating point.
Electrical assignments shared by every tube using this base designation.
No verified pinout is recorded for this base designation.
1 physical section, each with unique specifications.
Section 1
Ratings and characteristics extracted from 5A128B.pdf.
Source-dependent data
Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.
Data set 01
Published operating points and test conditions from this source.
Grid-anode capacitance
0.007 pF
Input capacitance
10.7 pF
Output capacitance
8 pF
Anode current
3.9 mA
Vp=250V;Vg2=100V;Vg1=-1.5V
Load
50000 ohm
Vp=250V;Vg2=100V
Output
0.315 W
Vp=250V;Vg2=100V
Data set 02
Published operating points and test conditions from this source.
Heater/filament voltage
4 V
Heater/filament current
950 mA
Plate resistance
800000 ohm
Amplification factor
2400
Maximum direct anode voltage
250 V
Maximum screen voltage
100 V
Data set 03
Published operating points and test conditions from this source.
GridToAnodeCapacitance
0.007 pF
Input Capacitance
10.7 pF
Output Capacitance
8 pF
MaximumDirectAnodeCurrent
9 mA