Power - Beam (NOT sweep) ·BeamPower-Pentode
12G11
Compactron dissimilar double pentode; the available reference does not reproduce enough application detail to justify a narrower functional classification.
- Sections
- 2
- Base
- 12BU
- Socket code
- B12C
- Base pins
- 12
- Nominal heater
- 12.6 V / 600 mA
Description
12G11 — Dissimilar Double Pentode Compactron
The 12G11 is a multi-electrode vacuum tube in the compactron family containing two dissimilar pentode sections: a power pentode (designated Section 1) and a sharp-cutoff, dual-control pentode (designated Section 2). Designed primarily for television receiver applications, Section 1 is tailored for use as an audio-frequency power output amplifier, while Section 2 is intended for use as an FM detector. The tube was registered under JEDEC release number 3531B on June 11, 1962.
Construction, Heater, and Physical Specifications
The 12G11 is constructed in a T-9 glass envelope utilizing a 12-pin button compactron base (E12-70) with a 12BU basing arrangement. The tube features coated unipotential cathodes. The physical dimensions of the envelope are as follows:
- Maximum Diameter: 1.188 inches
- Maximum Seated Height: 2.000 inches
- Maximum Overall Height: 2.375 inches
Heater Characteristics
The heater is designed for series or parallel operation, with controlled warm-up characteristics to ensure reliable performance in television receiver circuits.
| Parameter | Value |
|---|---|
| Heater Voltage (AC or DC) | 12.6 V |
| Heater Current | 0.6 ± 0.04 A (600 mA) |
| Heater Warm-up Time | 11 seconds |
For series heater string designs, the heater current must be centered at the nominal 0.6 A bogey value, with supply variations restricted to maintain the current within specified tolerances. The heater warm-up time is defined as the time required for the voltage across the heater to reach 80% of its rated value when four times the rated heater voltage is applied to a circuit consisting of the heater in series with a resistance equal to three times the nominal heater resistance (calculated as 3 * (12.6 V / 0.6 A) = 63 ohms).
Maximum Heater-Cathode Ratings
The insulation between the heater and the individual cathodes is rated under the Design Maximum Rating System:
- Heater Negative with Respect to Cathode: 200 V (Total DC and Peak)
- Heater Positive with Respect to Cathode: 100 V (DC), 200 V (Total DC and Peak)
Pinout and Basing Connections
The 12BU basing diagram provides the following pin connections, viewed from the bottom of the 12-pin compactron base:
- Pin 1: Plate (Section 2)
- Pin 2: Grid No. 2 / Screen Grid (Section 2)
- Pin 3: Grid No. 1 (Section 2)
- Pin 4: Cathode (Section 2)
- Pin 5: Internal Shield (IS)
- Pin 6: Grid No. 3 / Suppressor Grid (Section 2)
- Pin 7: Grid No. 1 (Section 1)
- Pin 8: Cathode, Grid No. 3, and Internal Shield (Section 1)
- Pin 9: Grid No. 2 / Screen Grid (Section 1)
- Pin 10: Plate (Section 1)
- Pin 11: Heater
- Pin 12: Heater
Section 1: Audio Power Pentode
Section 1 is a power pentode designed for Class A1 audio amplification. It is capable of delivering moderate power output at relatively low plate and screen voltages.
Design Maximum Ratings (Section 1)
- Plate Voltage: 150 V
- Screen Voltage (Grid No. 2): 135 V
- Plate Dissipation: 6.5 W
- Screen Dissipation: 1.8 W
- DC Cathode Current: 65 mA
Typical Operating Characteristics (Class A1 Amplifier)
| Parameter | Value |
|---|---|
| Plate Voltage | 120 V |
| Screen Voltage | 110 V |
| Grid No. 1 Voltage | -8.0 V |
| Peak AF Grid No. 1 Voltage | 8.0 V |
| Plate Resistance (Approx.) | 10,000 ohms |
| Transconductance | 7,500 umhos |
| Zero-Signal Plate Current | 49 mA |
| Maximum-Signal Plate Current | 50 mA |
| Zero-Signal Screen Current | 4.0 mA |
| Maximum-Signal Screen Current | 8.5 mA |
| Load Resistance | 2,500 ohms |
| Total Harmonic Distortion (Approx.) | 10% |
| Maximum-Signal Power Output | 2.3 W |
Section 2: Sharp-Cutoff, Dual-Control Pentode
Section 2 is a sharp-cutoff pentode featuring two independent control grids (Grid No. 1 and Grid No. 3), making it highly suitable for FM detection and similar applications requiring dual-control characteristics.
Design Maximum Ratings (Section 2)
- Plate Voltage: 330 V
- Suppressor Voltage (Grid No. 3): 28 V
- Screen Supply Voltage (Grid No. 2): 330 V
- Positive DC Grid No. 1 Voltage: 0 V
- Plate Dissipation: 1.7 W
- Screen Dissipation: 1.1 W
Typical Operating Characteristics
| Parameter | Value |
|---|---|
| Plate Voltage | 150 V |
| Suppressor Voltage (Grid No. 3) | 0 V |
| Screen Voltage | 100 V |
| Cathode Bias Resistor | 560 ohms |
| Plate Resistance (Approx.) | 0.15 Megohms |
| Grid No. 1 Transconductance | 1,000 umhos |
| Grid No. 3 Transconductance | 400 umhos |
| Plate Current | 1.3 mA |
| Screen Current | 2.0 mA |
| Grid No. 1 Voltage (Approx.) for Ib = 10 uA | -4.5 V |
| Grid No. 3 Voltage (Approx.) for Ib = 10 uA | -4.5 V |
Direct Interelectrode Capacitances
The direct interelectrode capacitances of the 12G11 are measured without an external shield.
Section 1 (Power Pentode)
- Grid No. 1 to Plate: 0.26 pF
- Input (Grid No. 1 to Heater, Cathode, Grid No. 2, Internal Shield): 12 pF
- Output (Plate to Heater, Cathode, Grid No. 2, Internal Shield): 12 pF
Section 2 (Dual-Control Pentode)
- Grid No. 1 to Plate: 0.034 pF
- Grid No. 3 to Plate: 2.8 pF
- Grid No. 1 to All Except Plate (Grid No. 1 to Heater, Cathode, Grid No. 2, Grid No. 3, Internal Shield): 6.5 pF
- Grid No. 3 to All (Grid No. 3 to Heater, Cathode, Grid No. 1, Grid No. 2, Plate, Internal Shield): 7.5 pF
- Grid No. 1 to Grid No. 3: 0.24 pF
Inter-Section Capacitance
- Plate (Section 1) to Plate (Section 2): 0.12 pF
Related Designations
The 12G11 is electrically identical to the 6G11, except for its heater characteristics. The 6G11 operates with a heater voltage of 6.3 V and a heater current of 1.2 A (1200 mA), whereas the 12G11 is configured for 12.6 V and 0.6 A (600 mA).
Socket description
Duodecar 12-contact
General specifications
Tube and section characteristics
Properties common to every published source and operating point.
Heater and base
- Base
- 12BU
- Socket code
- B12C
- Base pins
- 12
- Nominal heater voltage
- 12.6 V
- Nominal heater current
- 600 mA
- Parallel heater voltage
- -
- Parallel heater current
- -
- Series capable
- No
12BU - Terminal pinout
Electrical assignments shared by every tube using this base designation.
No verified pinout is recorded for this base designation.
Section ratings
2 physical sections, each with unique specifications.
Section 0
Pentode
No fixed ratings are recorded for this section.
Sparse-source exception: power pentode
Section 1
Beam Power
- Max plate voltage
- 165 V
- Max screen voltage
- 150 V
- Max plate dissipation
- 6.5 W
- Max screen dissipation
- 1.8 W
Sparse-source exception: dual-control pentode
Source-dependent data
Operating conditions by source
Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.