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Power - Pentode Single (NOT beam) (under 10W) ·Pentode

16A6

Power-amplifier pentode with a 16.5 V heater designed for Class-A audio-output service. Its primary function is low-frequency power delivery to an output load.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
9BL
Socket code
B9A
Base pins
9
Nominal heater
16.5 V / 300 mA

Description

16A6 — Power Amplifier Pentode

An indirectly heated power amplifier pentode designed for audio-frequency and power amplification applications.

Overview

The 16A6 is a power amplifier pentode designed for Class A amplifier service. It features an indirectly heated cathode with a nominal heater rating of 16.5 V and 0.3 A. The tube is constructed with a 9BL base connection configuration and is housed in an envelope designated by the 6-4 outline drawing. It is capable of delivering a rated power output of 4.0 W under typical operating conditions.

Physical and Heater Characteristics

The 16A6 utilizes an indirectly heated cathode structure. The heater is designed for operation at a nominal voltage of 16.5 V and a current of 0.3 A.

  • Heater Voltage: 16.5 V
  • Heater Current: 0.3 A
  • Calculated Heater Power: 4.95 W (calculated as 16.5 V multiplied by 0.3 A)
  • Cathode Type: Indirectly heated (heater-cathode construction)
  • Base Connection: 9BL
  • Outline Drawing: 6-4

Interelectrode Capacitances

The electrostatic capacitances of the 16A6 are specified without the use of an external shield. The direct interelectrode capacitances are as follows:

Capacitance ParameterValue
Input Capacitance11 pF
Output Capacitance5.9 pF
Grid-to-Plate Capacitance1.0 pF

The relatively low grid-to-plate capacitance of 1.0 pF is typical of pentode construction, helping to minimize feedback between the plate and the control grid.

Maximum Ratings

To ensure reliable operation and prevent premature failure, the operating potentials of the 16A6 must be maintained within the following maximum limits:

  • Maximum Plate Voltage: 250 V
  • Maximum Screen (Grid No. 2) Voltage: 250 V

Class A Amplifier Operating Conditions

Under typical Class A amplifier service, the 16A6 operates with equal plate and screen potentials. The typical operating parameters and performance characteristics are detailed below:

ParameterValue
Plate Voltage170 V
Screen Voltage170 V
Negative Grid (Grid No. 1) Voltage10.4 V
Plate Current53 mA
Screen Current10 mA
Plate Resistance (Approximate)20,000 Ω
Transconductance (gm)9,000 µmhos
Load Resistance3,000 Ω
Rated Power Output4.0 W

Operating Analysis and Calculations

At the specified operating point, the total cathode current is the sum of the plate and screen currents:

  • Total Cathode Current: 53 mA + 10 mA = 63 mA

The static plate dissipation under these conditions is calculated as:

  • Plate Dissipation: 170 V * 0.053 A = 9.01 W

The static screen dissipation is calculated as:

  • Screen Dissipation: 170 V * 0.010 A = 1.70 W

With a load resistance of 3,000 Ω, the tube achieves a power output of 4.0 W. The high transconductance of 9,000 µmhos indicates that the tube has high sensitivity, requiring a relatively small input signal voltage to drive it to full rated output.

Technical Summary

The 16A6 is a high-sensitivity power amplifier pentode featuring a 16.5 V, 0.3 A heater, a 9BL base, and a 6-4 outline. It is rated for a maximum plate and screen voltage of 250 V. In typical Class A amplifier service at 170 V on both plate and screen, it exhibits a transconductance of 9,000 µmhos, an approximate plate resistance of 20,000 Ω, and delivers 4.0 W of power output into a 3,000 Ω load.

Socket description

Small-button Noval 9-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
9BL
Socket code
B9A
Base pins
9
Nominal heater voltage
16.5 V
Nominal heater current
300 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

9BL - Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

1 physical section, each with unique specifications.

Section 1

Pentode

X-ray radiationInterelectrode capacitances
Plate resistance
20000 Ω
Transconductance
0.009 S
Max plate voltage
250 V
Max screen voltage
250 V
Max plate dissipation
9 W

Promoted from printed maximum-rating/characteristic columns; additional published values retained in TUBE_SECTION_PARAMETER.

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.

Data set 01

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Pentode

Capacitance

  • Input capacitance

    11 pF

    Section1

  • Output capacitance

    5.9 pF

    Section1

  • Grid-to-plate capacitance

    3 pF

    Section1

Other

  • Plate voltage

    170 V

    ClassA

  • Screen voltage

    170 V

    ClassA

  • Control-grid voltage

    -10.4 V

    ClassA

  • Plate current

    53 mA

    ClassA

  • Screen current

    10 mA

    ClassA

  • Load resistance

    3000 Ω

    ClassA

  • Power output

    4 W

    ClassA

Characteristic

  • Plate resistance

    20000 Ω

    ClassA

  • Transconductance

    9000 µS

    ClassA