C3g — Small Signal Pentode, Loctal | Tubeofile

C3g

Small Signal Pentode — Loctal

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Siemens & Halske / Telefunken

↗ r-type.org ↗ TDSL ↗ Radiomuseum

Known Equivalents & Substitutes

C3g/sCV10522

Similar Tubes (Not Drop-In Compatible)

5A/152M

STC coaxial repeater pentode with similar characteristics and application — different Loctal base variant (B8G), not pin-compatible with C3g continental Loctal

Electrical Specifications

Section 1 — Pentode

Absolute Maximum

Anode Voltage (max)Anode Voltage (max operating)220V

Screen Voltage (max)Screen Voltage (max operating)220V

Anode Dissipation (max)Anode Dissipation (max)3.5W

Screen Dissipation (max)Screen Dissipation (max)0.7W

Cathode Current (max)Cathode Current (max)30mA

Typical Operating

Anode Voltage (typical)Anode Voltage220V

Screen Voltage (typical)Screen Voltage150V

Grid 1 Bias VoltageGrid 1 Bias Voltage (cutoff)-4.5V

Anode CurrentAnode Current13mA

Screen CurrentScreen Current

Capacitances

Grid-to-Plate CapacitanceGrid-to-Plate Capacitance (Ca/g1)0.012pF

Grid-to-Cathode CapacitanceGrid-to-Cathode Capacitance (Cg1/k)5.5pF

Anode-to-Cathode CapacitanceAnode-to-Cathode Capacitance (Ca/k)0.008pF

Input CapacitanceInput Capacitance9.5pF

Output CapacitanceOutput Capacitance

other

No-signal Screen Supply Voltage (max)No-signal Screen Supply Voltage (max)550V

Equivalent Anode Load Resistance (RiL)Equivalent Anode Load Resistance (RiL)1.7kΩ

Grid 1 Dissipation (max)Grid 1 Dissipation (max)50mW

Equivalent Noise Resistance (Raeq)Equivalent Noise Resistance (Raeq)650Ω

Heater-Cathode Resistance (max)Heater-Cathode Resistance (max)

Section 2 — Triode Strapped

Typical Operating

Anode Voltage (typical)Anode Voltage200V

Grid 1 Bias VoltageGrid 1 Bias Voltage-3.1V

Anode CurrentAnode Current17mA

Anode ResistanceAnode Resistance2.3Ω

TransconductanceTransconductance

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current0.37A

Notes

C3g/s is a selected variant where transconductance exceeds 105% of nominal (≥14.7 mA/V).
Ua max of 220V is the operating limit; the no-signal supply voltage (Uao) may be up to 550V. Similarly Ug2o max is 550V but operating Ug2 max is 220V.
Both cathode pins (5 and 7) must be connected in parallel.
The metal screening can connects to the base center spigot (pin m) and should be grounded for proper shielding.
Heater voltage must be held within ±5% for guaranteed lifetime ratings to apply.
Loctal base with continental key socket — not pin-compatible with standard B8G/Loctal American types despite similar appearance.

Pin Layout — Loctal

1Heater

2Suppressor Grid (g3) + Shield

3Anode

References