19RP11 — Long-Life Miniature Power Pentode

The 19RP11 (also designated as 19R-P11) is a long-life, miniature power pentode designed primarily for use as a power amplifier in wire communication equipment. It features a compact physical design and is optimized for continuous-duty applications where high reliability is required. Due to its specialized long-life design, the tube is not suitable for applications where the circuit is frequently switched on and off.

Mechanical Design and Pinout

The 19RP11 is constructed in a T6 1/2 glass bulb envelope and utilizes an E9-1 Small Button Noval 9-pin base. The tube is designed to operate reliably in any mounting position, providing flexibility in physical equipment layouts.

The pin connections are arranged to provide dual connections for certain electrodes, which can assist in circuit layout and thermal management. Specifically, the control grid (Grid No. 1) is accessible on two separate pins, and the cathode, which is internally tied to the suppressor grid (Grid No. 3), is also brought out to two separate pins.

The physical pinout configuration, viewed from the bottom of the base, is detailed below:

Heater and Capacitance Characteristics

The 19RP11 is equipped with an indirectly heated cathode. The heater is designed for operation at a nominal voltage of 19.0 V and a nominal current of 0.2 A.

Heater Specifications

• Heater Voltage: 19.0 V
• Heater Current: 0.2 A
• Calculated Heater Power: 3.8 W (calculated as 19.0 V * 0.2 A)

Direct Interelectrode Capacitances

The tube's internal capacitances influence its high-frequency performance and stability. The direct interelectrode capacitances are specified as follows:

• Grid No. 1 to Plate (maximum): 0.15 pF (measured with an external shield)
• Input Capacitance: 9.5 pF (measured without an external shield)
• Output Capacitance: 5.5 pF (measured without an external shield)

Typical Operating Conditions

Under typical Class A1 amplifier operating conditions, the 19RP11 operates with moderate electrode voltages to balance power output and service life. A typical operating point is defined by the following parameters:

• Plate Voltage: 120 V
• Grid No. 2 (Screen Grid) Voltage: 120 V
• Grid No. 1 (Control Grid) Voltage: -7 V
• Plate Current: 35 mA
• Grid No. 2 Current: 7.5 mA
• Transconductance: 5,500 µmhos (micromhos)
• Plate Resistance (Approximate): 25 kΩ

Calculated Operating Values

From these typical operating parameters, several circuit-level values can be calculated:

• Total Cathode Current: 42.5 mA (calculated as the sum of typical plate current and screen grid current: 35 mA + 7.5 mA)
• Typical Plate Dissipation: 4.2 W (calculated as 120 V * 35 mA)
• Typical Grid No. 2 Dissipation: 0.9 W (calculated as 120 V * 7.5 mA)

These typical operating dissipations remain well within the absolute maximum limits established for the device, ensuring the long-life characteristics of the tube are maintained during standard operation.

Absolute Maximum Ratings

The absolute maximum ratings represent the physical limits beyond which the serviceability and life of the 19RP11 may be severely impaired. These ratings must not be exceeded under any operating conditions.

Technical Summary

The 19RP11 is a specialized, long-life miniature power pentode housed in a T6 1/2 envelope with a 9-pin Noval base. Designed for wire communication equipment, it provides reliable power amplification under continuous-duty conditions, provided that frequent on-off power cycling is avoided. With a 19.0 V, 0.2 A heater, a transconductance of 5,500 µmhos, and a maximum plate dissipation rating of 8.2 W, the 19RP11 offers robust performance in stable, long-term amplifier installations.