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Voltage Triode Pentode ·Pentode-Triode

5CM8

High-mu triode plus sharp-cutoff pentode, heater variant of the 6CM8.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
2
Base
9DZ
Socket code
B9A
Base pins
9
Nominal heater
4.7 V / 600 mA

Description

High-mu triode plus sharp-cutoff pentode, heater variant of 6CM8.

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
9DZ
Socket code
B9A
Base pins
9
Nominal heater voltage
4.7 V
Nominal heater current
600 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

9DZ - Terminal pinout

Electrical assignments shared by every tube using this base designation.

TerminalSectionConnectionEvidence
PIN1Pin 1BK — Cathode

Original chart label: 2K; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

PIN2Pin 2BG1 — Control Grid

Original chart label: 2G1; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

PIN3Pin 3BP — Plate (Anode)

Original chart label: 2P; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

PIN4Pin 4—H — Heater

Original chart label: H; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

PIN5Pin 5—H — Heater

Original chart label: H; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

PIN6Pin 6AG1 — Control Grid

Original chart label: 1G1; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

PIN7Pin 7AG3 — Suppressor GridGroup 9DZ7

Original chart label: 1G3; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

PIN7Pin 7AK — CathodeGroup 9DZ7

Original chart label: 1K; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

PIN7Pin 7—IS — Internal ScreenGroup 9DZ7

Original chart label: IS; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

PIN8Pin 8AG2 — Screen Grid

Original chart label: 1G2; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

PIN9Pin 9AP — Plate (Anode)

Original chart label: 1P; manufacturer verification pending

Unverified

EIA Base Connections, printed page 132, 9DZ

Section ratings

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances
Plate resistance
50000 Ω
Transconductance
0.002 S
Amplification factor
100
Max plate voltage
300 V
Max plate dissipation
1 W

Electrical characteristics cloned from explicit counterpart 6CM8; heater replaced by 5CM8 source values. High-mu triode section.

Section 2

Pentode

X-ray radiationInterelectrode capacitances
Plate resistance
600000 Ω
Transconductance
0.0062 S
Max plate voltage
300 V
Max screen voltage
300 V
Max plate dissipation
2 W
Max screen dissipation
0.5 W

Electrical characteristics cloned from explicit counterpart 6CM8; heater replaced by 5CM8 source values. Sharp-cutoff pentode section; grid-2 operating voltage is rating-chart limited.

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

1971 RCA HB3 Binder 4 of 7

Published operating points and test conditions from this source.

SECTION 1

Triode

Capacitance

  • Grid-to-plate capacitance

    1.9 pF

  • Input capacitance

    1.6 pF

  • Output capacitance

    0.22 pF

Other

  • Plate supply voltage

    250 V

    ClassA

  • Grid #1 voltage

    -2 V

    ClassA

  • Plate current

    1.8 mA

    ClassA

  • Heater/filament voltage

    4.7 V

    DerivativeSheet

  • Heater/filament current

    600 mA

    DerivativeSheet

  • Heater warm-up time

    11 s

    ControlledWarmup

SECTION 2

Pentode

Capacitance

  • Grid #1-to-plate capacitance

    0.04 pF

  • Input capacitance

    6 pF

  • Output capacitance

    2.6 pF

  • Pentode plate to triode grid capacitance

    0.01 pF

    Coupling

  • Pentode grid #1 to triode plate capacitance

    0.15 pF

    Coupling

  • Pentode plate to triode plate capacitance

    0.1 pF

    Coupling

Other

  • Plate supply voltage

    200 V

    ClassA

  • Grid #2 voltage

    150 V

    ClassA

  • Grid #1 voltage

    0 V

    ClassA

  • Cathode bias resistor

    180 ohm

    ClassA

  • Plate current

    9.5 mA

    ClassA

  • Grid #2 current

    2.8 mA

    ClassA

Characteristic

  • Grid #1 voltage at 10 uA plate current

    -8 V