Skip to main content
Tube Tinker — Electron Tube Database
Alternatives & variationsDownload PDF datasheet

Power - Triode ·Triode

7242

High-current triode for power electronic service. Available source material does not establish a narrower application confidently.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
A7-17
Socket code
B7G
Base pins
7
Nominal heater
6.3 V / 7.5 A

Description

High-current power triode intended for series-regulator service.

Socket description

Miniature 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
A7-17
Socket code
B7G
Base pins
7
Nominal heater voltage
6.3 V
Nominal heater current
7.5 A
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

A7-17 - 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

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
82 Ω
Transconductance
0.111 S
Amplification factor
9
Max plate voltage
400 V
Max plate dissipation
100 W
Max cathode current
900 mA

Representative row for three identical cathode-controlled power sections.

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

1960 Mazda

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • MaximumContinuousPlateCurrent

    900 mA

  • MaximumGridCurrent

    0 mA

  • Maximum Positive Grid Voltage

    0 V

  • Maximum Negative Grid Voltage

    -300 V

  • Maximum Heater Cathode Voltage

    300 V

  • MinimumWarmupTime

    30 s

  • Maximum Bulb Temperature

    300 degC

  • MaximumAltitudeWithoutPressurization

    3 km

Data set 02

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • MinimumCathodeHeatingTime

    30 s

  • CurrentPerCathodeMaximum

    200 mA

  • AltitudeForFullRatings

    10000 ft

  • ExtendedAltitudeWithCooling

    60000 ft

  • ShockRating

    450 g

  • VibrationRating

    2.5 g

  • Service

    Series regulator / passing tube

Data set 03

1966 Tung Sol Electronic Tubes 4 of 4

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

  • Total plate current maximum

    900 mA

    WholeTube

  • Current per cathode maximum

    300 mA

    WholeTube

  • Grid Current (Max.)

    12 uA

    PublishedTable

Characteristic

  • Minimum cathode heating time

    30 s

    WholeTube

  • Heater Voltage

    -10 VOLTS

    PublishedTable

  • Heater Current (E F= 6.3 V.)

    0.5 AMP

    PublishedTable

  • Plate Resistance

    8 OHMS

    PublishedTable

  • Total Plate Current Dc

    9 AMP

    PublishedTable

  • If Tube Voltage Drop Is To Be Swung More Than 6 Volts, This

    6 VOLTS

    PublishedTable

  • Current Per Cathode (Oc)

    3 MA

    PublishedTable

  • Plate Voltage (Dc)

    4 VOLTS

    PublishedTable

  • Heater-Cathode Voltage (Dc)

    300 VOLTS

    PublishedTable

  • Grid Voltage

    3 VOLTS

    PublishedTable

  • Heater Voltage

    6.9 VOLTS

    PublishedTable

  • Regulated Service Or With Fixed Bias

    0 OHMS

    PublishedTable

  • Cathode Bias Only

    0 OHMS

    PublishedTable

  • Be 27 Ohms Or That Resistance Necessary To Pro

    27 OHMS

    PublishedTable

  • Plate Current

    390 MA

    PublishedTable

  • Transconductance (Min.)

    0 uMHO

    PublishedTable

  • Total Plate Current

    690 MA

    PublishedTable

  • Transconductance

    0 uMHOS

    PublishedTable

  • Heater Current Per Tube

    7.88 AMP

    PublishedTable

Data set 04

1968 Mazda Belvu

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristics

  • Heater or filament voltage

    6.3 V

    Published nominal value

  • Heater or filament current

    7.5 A

    Published nominal value

  • Transconductance

    111000 µS

    Published nominal characteristic

  • Warm-up time

    30 s

    Minimum cathode heating time

  • Nominal anode current

    420 to 690 mA

    At 100 V anode and -4 V grid

Other

  • Maximum plate dissipation

    100 W

    Published limit