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Power - Beam (NOT sweep) ·BeamPower-BeamPower

28D7W

Sylvania 28D7W rugged low-voltage dual beam-power output tube for aircraft and mobile audio amplifiers and control equipment, with 28 V 400 mA heater and 8BS locking base.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
8BS
Socket code
-
Base pins
8
Nominal heater
28 V / 400 mA

Description

High-reliability dual triode intended for electronic equipment service.

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
8BS
Socket code
-
Base pins
8
Nominal heater voltage
28 V
Nominal heater current
400 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

8BS - 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 1

Beam Power

X-ray radiationInterelectrode capacitances
Plate resistance
4200 Ω
Transconductance
0.0034 S
Max plate voltage
100 V
Max screen voltage
67.5 V
Max plate dissipation
3 W
Max screen dissipation
0.5 W

Sylvania April 1953 28D7W rugged dual beam-power tube, physical beam-power section 1. Datasheet OCR often reads 28D1W, but 28D7W identified in application text; user authorized this interpretation. Absolute maximum per section plate 100 V, screen 67.5 V, plate dissipation 3 W, screen dissipation 0.5 W, heater-cathode 100 V. Typical Class A at Va 28 V, Vg2 28 V, fixed Vg1 -3.5 V: plate current average 12.5 mA, screen current 1 mA, gm 0.0034 A/V (range 0.0028–0.0048), rp ~4200 Ω, load 4 kΩ, output ~100 mW. Two sections can operate separately, in parallel, or push-pull. Heater 28 V 0.4 A shared. No intrinsic triode amplification factor for beam power section.

Section 2

Beam Power

X-ray radiationInterelectrode capacitances
Plate resistance
4200 Ω
Transconductance
0.0034 S
Max plate voltage
100 V
Max screen voltage
67.5 V
Max plate dissipation
3 W
Max screen dissipation
0.5 W

Sylvania April 1953 28D7W rugged dual beam-power tube, physical beam-power section 2. Datasheet OCR often reads 28D1W, but 28D7W identified in application text; user authorized this interpretation. Absolute maximum per section plate 100 V, screen 67.5 V, plate dissipation 3 W, screen dissipation 0.5 W, heater-cathode 100 V. Typical Class A at Va 28 V, Vg2 28 V, fixed Vg1 -3.5 V: plate current average 12.5 mA, screen current 1 mA, gm 0.0034 A/V (range 0.0028–0.0048), rp ~4200 Ω, load 4 kΩ, output ~100 mW. Two sections can operate separately, in parallel, or push-pull. Heater 28 V 0.4 A shared. No intrinsic triode amplification factor for beam power section.

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

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Other

  • Heater Voltage (Avg.) . . 28 Volts MAX

    28 V

    Heater Voltage (Avg.) . . 28 Volts MAX

  • Heater Voltage (Abs. Max.) 30 Volts

    30 V

    Heater Voltage (Abs. Max.) 30 Volts

  • Heater Current (Max.)1! . 435 Ma

    435 Ma

    Heater Current (Max.)1! . 435 Ma

  • Plate Current (Maximum Signal) . . . = . . . e e e 14.5 19.0 Ma

    19 Ma

    Plate Current (Maximum Signal) . . . = . . . e e e 14.5 19.0 Ma

  • Screen Current (Maximum Signal) . . . . . . . . . . . . . 2.5 3.0 Ma

    3 Ma

    Screen Current (Maximum Signal) . . . . . . . . . . . . . 2.5 3.0 Ma

  • Plate Current (Maximum Signal) . . . . . . . . . . . . . . 13.1 16.0 Ma

    16 Ma

    Plate Current (Maximum Signal) . . . . . . . . . . . . . . 13.1 16.0 Ma

  • Screen Current (Maximum Signal) . . . . . . . . . . . . . 2.8 3.5 Ma

    3.5 Ma

    Screen Current (Maximum Signal) . . . . . . . . . . . . . 2.8 3.5 Ma

  • Plate Current (Maximum Sxgnal) e e e e e e e e e e 58.0 Ma

    58 Ma

    Plate Current (Maximum Sxgnal) e e e e e e e e e e 58.0 Ma

  • Screen Current (Maximum Signal) . e e e e e e e e e 17.0 Ma

    17 Ma

    Screen Current (Maximum Signal) . e e e e e e e e e 17.0 Ma

  • 3. These ratings may be realized, provided the dc plate circuit resistance does not exceed 50 ohms p

    50 ohms

    3. These ratings may be realized, provided the dc plate circuit resistance does not exceed 50 ohms per section.

Characteristic

  • Heater Voltage (Design Center) 28 Volts

    28 V

    Heater Voltage (Design Center) 28 Volts

  • Heater Current (Avg.) 400 Ma

    400 Ma

    Heater Current (Avg.) 400 Ma

  • Heater Current (Min.)1 . 365 Ma

    365 Ma

    Heater Current (Min.)1 . 365 Ma

  • Plate Voltage . . . . . . . . . . . 100 100 Volts

    100 V

    Plate Voltage . . . . . . . . . . . 100 100 Volts

  • Screen Voltage . . . . . . . . . . . 675 67.5 Volts

    67.5 V

    Screen Voltage . . . . . . . . . . . 675 67.5 Volts

  • Plate Dissipation . . . . . . . . . . 30 3.0 Watts

    3 W

    Plate Dissipation . . . . . . . . . . 30 3.0 Watts

  • Screen Dissipation . . . . . . . . . . 05 0.5 Watt

    0.5 W

    Screen Dissipation . . . . . . . . . . 05 0.5 Watt

  • Heater-Cathode Voltage . . . . . . . . 100 90 Volts

    90 V

    Heater-Cathode Voltage . . . . . . . . 100 90 Volts

  • Plate Current (Zero Slgnal) . 9.0 8.0 12.5 17.5 Ma

    17.5 Ma

    Plate Current (Zero Slgnal) . 9.0 8.0 12.5 17.5 Ma

  • Screen Current (Zero Signal) . 0.7 0.2 1.0 2.2 Ma

    2.2 Ma

    Screen Current (Zero Signal) . 0.7 0.2 1.0 2.2 Ma

  • Plate Voltage® . . . . . . . . . . . . . . . . . ... 28.0 28.0 Volts

    28 V

    Plate Voltage® . . . . . . . . . . . . . . . . . ... 28.0 28.0 Volts

  • Screen Voltage . . . . . . . . . . . . o . . . ..o 28.0 28.0 Volts

    28 V

    Screen Voltage . . . . . . . . . . . . o . . . ..o 28.0 28.0 Volts

  • GridVoltage . . . . . . . « « . . . . . . . . ... — -3.5 Volts

    -3.5 V

    GridVoltage . . . . . . . « « . . . . . . . . ... — -3.5 Volts

  • Screen Current (Zero Signal) 1.2 2.0 Ma

    2 Ma

    Screen Current (Zero Signal) 1.2 2.0 Ma

  • Peak AF Signal Voltage (Grid to Grid) . . . . . . . . . . . . 9.8 9.8 Volts

    9.8 V

    Peak AF Signal Voltage (Grid to Grid) . . . . . . . . . . . . 9.8 9.8 Volts

  • Load Resistance (Plateto Plate) . . . . . . . . . . . . . . 6000 6000 Ohms

    6000 Ohms

    Load Resistance (Plateto Plate) . . . . . . . . . . . . . . 6000 6000 Ohms

  • Parallel Resistance Coupled ClassA2 Amphfier (BothSections)

    2 A

    Parallel Resistance Coupled ClassA2 Amphfier (BothSections)

  • Plate Voltage3 . . . . . e e . 0. 280 28.0 Volts

    28 V

    Plate Voltage3 . . . . . e e . 0. 280 28.0 Volts

  • Screen Voltage . . . . . . . . . . . . . . . . ... 28.0 28.0 Volts

    28 V

    Screen Voltage . . . . . . . . . . . . . . . . ... 28.0 28.0 Volts

  • GridVoltage . . . . . . . . . . . . . . . . . ... —_ -3.5 Volts

    -3.5 V

    GridVoltage . . . . . . . . . . . . . . . . . ... —_ -3.5 Volts

  • Plate Current (Zero Signal) . . . . . . . . . . . . . . . . 18.5 25.0 Ma

    25 Ma

    Plate Current (Zero Signal) . . . . . . . . . . . . . . . . 18.5 25.0 Ma

  • Screen Current (Zero Signal) . . . . . . . . . . . . . . . 1.3 2.0 Ma

    2 Ma

    Screen Current (Zero Signal) . . . . . . . . . . . . . . . 1.3 2.0 Ma

  • Peak AF Signal Voltage . . . . . . . . . . . . . . . . . 4.9 4.9 Volts

    4.9 V

    Peak AF Signal Voltage . . . . . . . . . . . . . . . . . 4.9 4.9 Volts

  • Load Resistance. . . e e e e e e e e e oo v . 2000 2000 Ohms

    2000 Ohms

    Load Resistance. . . e e e e e e e e e oo v . 2000 2000 Ohms

  • Plate Voltage3 . . . . . . . . . e e e e e 28.0 Volts

    28 V

    Plate Voltage3 . . . . . . . . . e e e e e 28.0 Volts

  • Screen Voltage . . . . . . . . . . . . . . . . ... 28.0 Volts

    28 V

    Screen Voltage . . . . . . . . . . . . . . . . ... 28.0 Volts

  • Plate Current (Zero Slgnal) e e e e e e e e e e e e e 64.0 Ma

    64 Ma

    Plate Current (Zero Slgnal) e e e e e e e e e e e e e 64.0 Ma

  • Screen Current (Zero Signal) . . . . . . . . . . . . . .. 4.0 Ma

    4 Ma

    Screen Current (Zero Signal) . . . . . . . . . . . . . .. 4.0 Ma

  • Peak AF Signal Voltage (Grid to Gnd) e e e e e e e e 17.8 Volts

    17.8 V

    Peak AF Signal Voltage (Grid to Gnd) e e e e e e e e 17.8 Volts

  • Load Resistance (Plate to Plate) . . . . . . . . . . . . . . 1560 Ohms

    1560 Ohms

    Load Resistance (Plate to Plate) . . . . . . . . . . . . . . 1560 Ohms

  • permits utilization of the total supply voltage. An increase in- effective B voltage of about 3.5 vo

    3.5 V

    permits utilization of the total supply voltage. An increase in- effective B voltage of about 3.5 volts is an

  • Power output and distortion data on Type 28D7W are given in the following table with the heater, pla

    7 W

    Power output and distortion data on Type 28D7W are given in the following table with the heater, plate and

  • screen voltages varied from 22 volts to 30 volts under fixed-bias and self-bias conditions. Values s

    30 V

    screen voltages varied from 22 volts to 30 volts under fixed-bias and self-bias conditions. Values shown are for

  • 28 volts, a resistor should be inserted in series with the heater supply voltage and the heater.

    28 V

    28 volts, a resistor should be inserted in series with the heater supply voltage and the heater.

  • Several methods of driving the Type 28D7W tube are very satisfactory for applications where a 28 vol

    28 V

    Several methods of driving the Type 28D7W tube are very satisfactory for applications where a 28 volt power