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Power - TV Vertical Output ·Triode-Triode

15EW7

Dissimilar dual triode designed for combined television vertical-deflection oscillator and amplifier service. It combines a small-signal oscillator section with a 10 W power section and published high pulse-voltage ratings.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
9HF
Socket code
B9A
Base pins
9
Nominal heater
14.8 V / 450 mA

Description

15EW7 — Dissimilar Double Triode

An indirectly heated, dissimilar double triode designed for television vertical-deflection oscillator and vertical-deflection amplifier applications.

Overview

The 15EW7 is a miniature, dissimilar double triode containing two highly distinct triode units within a single glass envelope. Unit 1 is a medium-mu triode optimized for vertical-deflection oscillator service, while Unit 2 is a low-mu, high-current power triode designed for vertical-deflection amplification.

The 15EW7 belongs to a family of identical tubes that differ only in their heater ratings, which includes the 6EW7, 10EW7, 19EW7, and 20EW7.

Construction, Physical Dimensions, and Basing

The 15EW7 is constructed in a T9 glass bulb with a 9-pin button base (E9-68). It is classified as a neonoval or miniature 9-contact type. The physical dimensions are as follows:

  • Maximum Diameter: 1.188 inches
  • Maximum Seated Height: 2.620 inches
  • Maximum Overall Height: 2.930 inches

The tube utilizes the 9HF basing arrangement. The pin connections, viewed from the bottom of the tube, are:

  • Pin 1: Plate of Triode Unit 1 (1P)
  • Pin 2: Grid of Triode Unit 2 (2G)
  • Pin 3: Grid of Triode Unit 2 (2G) (internally connected to Pin 2)
  • Pin 4: Heater (H)
  • Pin 5: Heater (H)
  • Pin 6: Plate of Triode Unit 2 (2P)
  • Pin 7: Grid of Triode Unit 1 (1G)
  • Pin 8: Cathode of Triode Unit 1 (1K)
  • Pin 9: Cathode of Triode Unit 2 (2K)

This configuration provides separate cathode connections for each triode, allowing them to be operated at different bias levels, provided heater-to-cathode voltage limits are respected.

Heater Characteristics and Family Variants

The 15EW7 features an indirectly heated cathode with a controlled warm-up time. The heater characteristics of the 15EW7 and its related family members are detailed below:

Tube DesignationHeater Voltage (AC/DC)Heater CurrentCalculated Heater PowerHeater Warm-up Time
6EW76.3 V0.90 A5.67 W—
10EW79.7 V0.60 A5.82 W11 seconds
15EW714.8 V0.45 A6.66 W11 seconds
19EW718.9 V0.30 A5.67 W11 seconds
20EW720.5 V0.30 A6.15 W11 seconds

Heater-Cathode Voltage Limits

For all family members, the maximum heater-cathode ratings under the Design-Maximum System are:

  • Heater Negative with Respect to Cathode:
    • Total DC and Peak: 200 V max
  • Heater Positive with Respect to Cathode:
    • DC: 100 V max
    • Total DC and Peak: 200 V max

Electrical Characteristics and Class A1 Operation

The two triode sections of the 15EW7 have highly dissimilar electrical characteristics. Unit 1 is a medium-mu voltage amplifier, whereas Unit 2 is a low-mu power triode with low plate resistance and high transconductance.

The typical operating characteristics for each section under Class A1 amplifier conditions are:

ParameterUnit 1 (Oscillator)Unit 2 (Amplifier)
Plate Voltage250 V150 V
Grid Voltage-11 V-17.5 V
Amplification Factor17.56.0
Plate Resistance (Approx.)8,750 ̩800 ̩
Transconductance2,000 mhos7,500 mhos
Plate Current5.5 mA45 mA
Plate Current (at Eb = 60 V, Ec = 0 V)—95 mA
Plate Current (at Ec = -25 V)—8 mA
Grid Voltage for 10 A Plate Current (Approx.)-20 V—
Grid Voltage for 100 A Plate Current (Approx.)—-40 V

Direct Interelectrode Capacitances

The approximate unshielded capacitances for each section are:

  • Unit 1:
    • Grid to Plate: 4.2 pF
    • Grid to Cathode and Heater: 2.2 pF
    • Plate to Cathode and Heater: 0.4 pF
  • Unit 2:
    • Grid to Plate: 9.0 pF
    • Grid to Cathode and Heater: 7.0 pF
    • Plate to Cathode and Heater: 1.2 pF

Vertical-Deflection Service and Design-Maximum Ratings

In television receiver applications, the 15EW7 operates in a 525-line, 30-frame system. The maximum ratings and circuit values for each section under these conditions are:

Rating / ValueUnit 1 (Oscillator)Unit 2 (Amplifier)
DC Plate Voltage (Max.)330 V330 V
Peak Positive-Pulse Plate Voltage (Max.)—1,500 V
Peak Negative-Pulse Grid Voltage (Max.)400 V250 V
Peak Cathode Current (Max.)77 mA175 mA
Average Cathode Current (Max.)22 mA50 mA
Plate Dissipation (Max.)1.5 W10 W
Grid-Circuit Resistance (Self-Bias Max.)2.2 M̩2.2 M̩
Grid-Circuit Resistance (Grid-Resistor-Bias Max.)2.2 M̩2.2 M̩

Under television vertical deflection service, the peak positive-pulse plate voltage rating of 1,500 V for Unit 2 is subject to a pulse duration limit of 15% of a scanning cycle (which corresponds to 2.5 milliseconds). In stages operating with grid-leak bias, an adequate bias resistor or other suitable means must be employed to protect the tube from damage in the event that excitation is lost.

Plate Characteristics and Curve Interpretation

The plate characteristics of the two units reflect their distinct design roles:

  • Unit 1: The average plate characteristics of Unit 1 are identical to those of the Unit 1 section of the 6DE7. This section behaves as a standard medium-mu triode, providing stable voltage amplification and oscillation.
  • Unit 2: The plate characteristics of Unit 2 show a very high current capability at low plate voltages. At zero grid bias (Ec = 0 V), the plate current rises steeply, reaching 95 mA at a plate voltage of only 60 V. As negative grid bias is increased, the curves shift to the right, demonstrating the low plate resistance of 800 ohms. This allows Unit 2 to deliver the high peak currents required to drive the vertical deflection coils of a television picture tube.

Technical Summary

The 15EW7 is a versatile, dissimilar double triode featuring a 14.8 V, 0.45 A heater with an 11-second warm-up time. Housed in a T9 bulb with a 9-pin button base and a 9HF pinout, it combines a medium-mu oscillator triode (Unit 1: ̠ = 17.5, g∕ = 2,000 mhos) and a high-power, low-impedance amplifier triode (Unit 2: ̠ = 6.0, g∕ = 7,500 mhos, 10 W plate dissipation) in a single envelope. It is electrically identical to the 6EW7, 10EW7, 19EW7, and 20EW7 except for its specific heater ratings.

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
9HF
Socket code
B9A
Base pins
9
Nominal heater voltage
14.8 V
Nominal heater current
450 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

9HF - Terminal pinout

Electrical assignments shared by every tube using this base designation.

TerminalSectionConnectionEvidence
PIN1Base PinBP — Plate (Anode)

Literal label 2P; manufacturer confirmation pending

Unverified

EIA Base Connections printed p132, 9HF

PIN2Base PinBG1 — Control Grid

Literal label 2G1; manufacturer confirmation pending

Unverified

EIA Base Connections printed p132, 9HF

PIN3Base PinBG3 — Suppressor Grid

Literal label 2G3; manufacturer confirmation pending

Unverified

EIA Base Connections printed p132, 9HF

PIN4Base Pin—H — Heater

Literal label H; manufacturer confirmation pending

Unverified

EIA Base Connections printed p132, 9HF

PIN5Base Pin—H — Heater

Literal label H; manufacturer confirmation pending

Unverified

EIA Base Connections printed p132, 9HF

PIN6Base PinAP — Plate (Anode)

Literal label 1P; manufacturer confirmation pending

Unverified

EIA Base Connections printed p132, 9HF

PIN7Base PinAG1 — Control Grid

Literal label 1G1; manufacturer confirmation pending

Unverified

EIA Base Connections printed p132, 9HF

PIN8Base PinAK — Cathode

Literal label 1K; manufacturer confirmation pending

Unverified

EIA Base Connections printed p132, 9HF

PIN9Base PinBK — Cathode

Literal label 2K; manufacturer confirmation pending

Unverified

EIA Base Connections printed p132, 9HF

Section ratings

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
8750 Ω
Transconductance
0.002 S
Amplification factor
17.5
Max plate voltage
330 V
Max plate dissipation
1.5 W
Max cathode current
22 mA

Promoted from published ratings/characteristics where directly applicable; additional published values retained in TUBE_SECTION_PARAMETER.

Section 2

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
800 Ω
Transconductance
0.0075 S
Amplification factor
6
Max plate voltage
330 V
Max plate dissipation
10 W
Max cathode current
50 mA

Promoted from published ratings/characteristics where directly applicable; 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

1975 RCA RC30

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

  • Grid-No

    125 volts

    Published value from supplied target entry

  • Plate Resistance (Approx.)

    0.2 megohm

    Published value from supplied target entry

  • Transconductance

    14000

    Published value from supplied target entry

  • Grid-No

    2

    Published value from supplied target entry

  • Grid-No.l Voltage (Approx.) for plate current of

    3.5 volts

    Published value from supplied target entry

  • Heater Voltage (ac/dc)

    14.8 volts

    Published value from supplied target entry

  • Heater Current

    0.45 ampere

    Published value from supplied target entry

  • Plate Voltage

    150 volts

    Published value from supplied target entry

  • Plate Current for plate voltage of

    60 volts

    Published value from supplied target entry

  • Grid Voltage (Approx.) for plate current of

    -20 volts

    Published value from supplied target entry

  • Grid Voltage (Approx.) for plate current of

    -40 volts

    Published value from supplied target entry

  • DC Plate Voltage

    330 volts

    Published value from supplied target entry

  • Peak Positive-Pulse Plate Voltage*

    1500 volts

    Published value from supplied target entry

  • Peak Negative-Pulse Grid Voltage

    250 volts

    Published value from supplied target entry

  • Peak Cathode Current

    175 mA

    Published value from supplied target entry

  • Average Cathode Current

    50 mA

    Published value from supplied target entry

  • Plate Dissipation

    10 watts

    Published value from supplied target entry

  • Heater Voltage (ae/dc)

    13 volts

    Published value from supplied target entry

  • Heater Warm-up Time (Average)

    11 seconds

    Published value from supplied target entry

Capacitance

  • Direct Interelectrode Capacitances (Approx.) : Unit No.l Unit No

    2

    Published value from supplied target entry

  • Grid to Plate

    9 pF

    Published value from supplied target entry

  • Grid to Cathode and Heater

    7 pF

    Published value from supplied target entry

  • Plate to Cathode and Heater

    1.2 pF

    Published value from supplied target entry

  • Grid to Plate

    10 PF

    Published value from supplied target entry

  • Grid to Cathode and Heater

    6.5 PF

    Published value from supplied target entry