11E13 — High-Frequency Double Tetrode

The 11E13 is an indirectly heated, miniature-based high-frequency (H.F.) double tetrode. It is internally neutralised and specifically designed for use as a push-pull amplifier at frequencies up to 225 Mc/s.

Construction, Heater, and Physical Specifications

The 11E13 is constructed with a miniature glass envelope and utilizes a standard Noval (B9A) base. The physical dimensions of the device are specified as follows:

• Maximum Overall Length: 78.5 mm
• Maximum Seated Height: 71.5 mm
• Maximum Diameter: 22.2 mm

Heater Characteristics

The tube features a center-tapped heater design, allowing for operation from either a 6.3 V or 12.6 V power source. The electrical requirements for the heater are:

• Parallel Connection (6.3 V nominal): Heater voltage ($V_h$) of 6.3 V with a heater current ($I_h$) of 0.83 A.
• Series Connection (12.6 V nominal): Heater voltage ($V_h$) of 12.6 V with a heater current ($I_h$) of 0.42 A.

Mounting Position

The mounting position of the 11E13 is unrestricted. However, when the tube is mounted horizontally, pins 2 and 7 must be aligned in the same vertical plane.

Base Connections

The Noval (B9A) base pinout, viewed from the free end of the pins, is configured as follows:

• Pin 1: Control Grid, Section 1 ($g1'$)
• Pin 2: Cathode, Shield ($k, s$)
• Pin 3: Control Grid, Section 2 ($g1''$)
• Pin 4: Heater ($h$)
• Pin 5: Heater ($h$)
• Pin 6: Anode, Section 1 ($a'$)
• Pin 7: Screen Grid ($[g2](/tubes/G2)', [g2](/tubes/G2)''$)
• Pin 8: Anode, Section 2 ($a''$)
• Pin 9: Heater Centre Tap ($h_{ct}$)

The two tetrode sections share a common cathode and internal shield connected to Pin 2, and a common screen grid connected to Pin 7.

Electrical Characteristics and Capacitances

The typical electrical characteristics for each individual tetrode section, measured at an anode current ($I_a$) of 30 mA, are:

• Mutual Conductance ($g_m$): 3.3 mA/V
• Inner Amplification Factor ($\mu_{g1-g2}$): 7.5

Inter-Electrode Capacitances

The 11E13 is internally neutralised for push-pull operation, which significantly reduces the feedback capacitance between the anode and the control grid. The capacitances are defined as:

Absolute Maximum Ratings

All limiting values are specified under the Absolute Rating System, not Design Centres. The maximum operating frequency ($f_{max}$) is 225 Mc/s. The maximum permissible temperature of the hottest part of the bulb is 225 °C, and the maximum permissible temperature of the base pins is 120 °C. The maximum heater-to-cathode voltage ($V_{h-k(max)}$) is 100 V across all operating modes.

The absolute maximum ratings vary depending on the specific class of service:

Class "C" R.F. Amplifier (C.W. Telegraphy or F.M. Telephony)

For continuous wave (c.w.) telegraphy or frequency modulated (f.m.) telephony applications, the absolute maximum ratings per section (unless otherwise noted) are:

• Maximum Anode Voltage ($V_{a(max)}$): 300 V
• Maximum Screen Grid Voltage ($V_{[g2](/tubes/G2)(max)}$): 200 V
• Maximum Negative Control Grid Voltage ($V_{g1(max)}$): -150 V
• Maximum Anode Dissipation ($P_{a(max)}$): 5.0 W
• Maximum Screen Grid Dissipation ($P_{[g2](/tubes/G2)(max)}$): 1.0 W
• Maximum Control Grid Dissipation ($P_{g1(max)}$): 0.2 W
• Maximum Peak Cathode Current ($i_{k(pk)max}$): 225 mA
• Maximum Mean Cathode Current ($I_{k(av)max}$): 50 mA
• Maximum Mean Control Grid Current ($I_{g1(av)max}$): 3.0 mA

Class "C" R.F. Amplifier with Anode and Screen Grid Modulation

Under carrier conditions for use with a modulation factor of 1, the absolute maximum ratings per section (unless otherwise noted) are:

• Maximum Anode Voltage ($V_{a(max)}$): 250 V
• Maximum Screen Grid Voltage ($V_{[g2](/tubes/G2)(max)}$): 200 V
• Maximum Negative Control Grid Voltage ($V_{g1(max)}$): -150 V
• Maximum Anode Dissipation ($P_{a(max)}$): 3.3 W
• Maximum Screen Grid Dissipation ($P_{[g2](/tubes/G2)(max)}$): 0.65 W
• Maximum Control Grid Dissipation ($P_{g1(max)}$): 0.2 W
• Maximum Peak Cathode Current ($i_{k(pk)max}$): 180 mA
• Maximum Mean Cathode Current ($I_{k(av)max}$): 40 mA
• Maximum Mean Control Grid Current ($I_{g1(av)max}$): 3.0 mA

Frequency Trebler Service

When operated as a frequency trebler, the absolute maximum ratings per section (unless otherwise noted) are:

• Maximum Anode Voltage ($V_{a(max)}$): 300 V
• Maximum Screen Grid Voltage ($V_{[g2](/tubes/G2)(max)}$): 200 V
• Maximum Negative Control Grid Voltage ($V_{g1(max)}$): -150 V
• Maximum Anode Dissipation ($P_{a(max)}$): 5.0 W
• Maximum Screen Grid Dissipation ($P_{[g2](/tubes/G2)(max)}$): 1.0 W
• Maximum Control Grid Dissipation ($P_{g1(max)}$): 0.2 W
• Maximum Peak Cathode Current ($i_{k(pk)max}$): 225 mA
• Maximum Mean Cathode Current ($I_{k(av)max}$): 35 mA
• Maximum Mean Control Grid Current ($I_{g1(av)max}$): 2.0 mA

Technical Summary

The 11E13 is a high-frequency double tetrode designed for push-pull RF amplification and frequency multiplication up to 225 Mc/s. Featuring internal neutralisation, a flexible 6.3 V / 12.6 V heater, and a compact Noval (B9A) base, it provides up to 5.0 W of anode dissipation per section in Class C telegraphy or frequency trebler service. Its shared cathode/shield and screen grid connections simplify push-pull circuit layouts while maintaining low feedback capacitance.