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Voltage Radio Detector Converter ·Heptode

2A7

Pentagrid oscillator-converter for early superheterodyne receivers. It combines local oscillation and mixing in one multi-grid tube, providing useful conversion gain in early AC-powered radio equipment.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
7CI
Socket code
UX7
Base pins
7
Nominal heater
2.5 V / 800 mA

Description

Pentagrid converter for frequency-conversion service.

Socket description

Small 7-contact (0.75-inch pin circle)

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
7CI
Socket code
UX7
Base pins
7
Nominal heater voltage
2.5 V
Nominal heater current
800 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

7CI - 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

Heptode

X-ray radiationInterelectrode capacitances
Plate resistance
360000 Ω
Transconductance
0.00055 S
Max plate voltage
300 V
Max screen voltage
100 V
Max plate dissipation
1 W
Max screen dissipation
0.3 W

Pentagrid-converter section; conversion transconductance is preserved as parameters rather than promoted as ordinary gm.

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

1937 Raytheon Radio Receiving Tubes

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

  • Maximum plate voltage

    250 V

    Published datasheet rating

  • Maximum screen voltage

    100 V

    Published datasheet rating

  • Plate voltage

    250 V

    ClassA

  • Screen voltage

    100 V

    ClassA

  • Control-grid bias

    3 V

    ClassA

  • Plate current

    3.5 mA

    ClassA

  • Screen current

    2.7 mA

    ClassA

  • Anode-grid voltage

    100 V

    Converter Oscillator

  • Oscillator grid resistor

    50000 ohm

    Converter Oscillator

  • Oscillator grid current

    0.4 mA

    Converter Oscillator

Characteristic

  • Plate resistance

    300000 ohm

    Published datasheet characteristic

  • Transconductance

    550 µS

    Published datasheet characteristic

  • Heater/filament voltage

    2.5 V

    Published heater/filament rating

  • Heater/filament current

    800 mA

    Published heater/filament rating

  • Conversion transconductance

    550 µS

    Converter

Capacitance

  • Input capacitance

    8.5 pF

    Published capacitance

  • Output capacitance

    8 pF

    Published capacitance

  • Grid-to-plate capacitance

    0.3 pF

    Published capacitance

Data set 02

1940 RCA

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

  • iYe MA!."

    1 mA

    iYe MA!."1

  • a-c receivers having a

    2.5 V

    a-c receivers having a 2.5-volt heater supply. For general discussion of pentagrid

  • HEATER VOLTAGE (A. C.or D.C).u.vvvviinn

    2.5 V

    HEATER VOLTAGE (A. C.or D.C).u.vvvviinn... 2.5 Volts

  • HEATER CURRENT ...iiiiiinnnnnnennerennnnnnns

    800 mA

    HEATER CURRENT ...iiiiiinnnnnnennerennnnnnns 0.8 Ampere

  • OUTPUT €,C

    0 pF

    OUTPUT €,C2:€5:Cg:C7 = 0.l PF

  • R} =

    0.1 ohm

    R} = 250000 OHMS, 0.1 WATT

  • R2= 10000 ~5C000 OHMS, 0.) WATT

    0 ohm

    R2= 10000 ~5C000 OHMS, 0.) WATT

  • R4= 150~300 OHMS, 0.] WATT

    0 ohm

    R4= 150~300 OHMS, 0.] WATT

  • TRACKING CONO.(!

    7300 pF

    . TRACKING CONO.(! 17 D f 400 BPf 1070 Upf 2900 LBF | 7300 UUF

Data set 03

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Heptode

Characteristic

  • Tension de chauffage ... .. 2,5 volts

    2.5 V

    Tension de chauffage ... .. 2,5 volts

  • Courant de chauffage ... . 0,8 ampére

    800 mA

    Courant de chauffage ... . 0,8 ampére

Data set 04

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

  • Oscillator-grid current

    0.4 mA

    Converter

  • Oscillator-grid resistor

    50000 Ω

    Converter

  • Plate voltage

    250 V

    Converter

  • Screen voltage

    100 V

    Converter

  • Control-grid voltage

    -3 V

    Converter

  • Plate current

    3.5 mA

    Converter

  • Screen current

    2.7 mA

    Converter

  • Oscillator-plate voltage

    250 V

    Converter

  • Oscillator-plate series resistance

    20000 Ω

    Converter

  • Oscillator-plate current

    4 mA

    Converter

Characteristic

  • Plate resistance

    360000 Ω

    Converter

  • Conversion transconductance

    550 µS

    Converter

Data set 05

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Heptode

Other

  • OscillatorAnodeSupplyVoltageMaximum

    300 V

  • OscillatorAnodeVoltageMaximum

    200 V

  • OscillatorAnodeDissipationMaximum

    0.75 W

Capacitance

  • RF Input Capacitance

    8.5 pF

  • Oscillator Input Capacitance

    7 pF

  • OscillatorOutputCapacitance

    5.5 pF

  • MixerOutputCapacitance

    9 pF

Characteristic

  • Conversion Transconductance

    360 uS

    ConverterService