Pen4VB — Power Pentode, B7G | Tubeofile | Tubeofile
TUBEOFILE
← Browse Medium quality — at least 60% of universal parameters and pins are present, but some key data is missing. Verify specific values against datasheets before critical use.
Known Equivalents & Substitutes
Similar Tubes (Not Drop-In Compatible)
AC2/Pen
Radiomuseum lists as normally replaceable — similar power pentode N41
Radiomuseum lists as normally replaceable alternative PT4
Radiomuseum lists as normally replaceable — similar Mullard power pentode Electrical Specifications
Absolute Maximum
Screen Voltage (max) Maximum Screen Voltage 200V
Anode Dissipation (max) Maximum Anode Dissipation 6W
Typical Operating
Anode Voltage (typical) Plate Voltage 250V
Grid 1 Bias Voltage Grid Voltage -5.8V
Notes
Unusually high transconductance (gm = 10 mA/V) for a 1930s power pentode. Self-bias: 145 ohms cathode resistor needed for -5.8V bias at Va=250V, Vg2=100V. Uses the old British 7-pin base (M7A) — not to be confused with the later B7G miniature base. Brans Vademecum table Vc lists PenA4 and UCL82 as equivalents, though UCL82 is a triode-pentode compound tube and not a true equivalent. Production era: primarily 1931-1937 per Radiomuseum documentation. Pin Layout — B7G
1 2 3 4 5 6 7
1 Anode
2 Screen Grid (g2)
3 Control Grid (g1)
4
Anode Current Anode Current
30mA
Screen Voltage Screen Voltage 100V
Anode Resistance Internal Plate Resistance 30,000Ω
Transconductance Transconductance 10mA/V
Cathode Resistor (self-bias) Self-Bias Cathode Resistor 145Ω
Heater
Heater Voltage Heater Voltage 4V
Heater Current Heater Current 1.95A
Cathode