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Voltage Pentode - Remote Cutoff (single) ·Pentode

CF3

All-current variable-mu pentode explicitly associated with the AF3 regulating-pentode family. Its extended-control characteristic is intended for automatic gain regulation in receiver high-frequency signal stages.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
-
Socket code
P8A
Base pins
8
Nominal heater
13 V / 200 mA

Description

All-current variable-mu pentode, explicitly cross-referenced to the AF3 regulating-pentode family.

Socket description

European 8-pin side-contact base

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
-
Socket code
P8A
Base pins
8
Nominal heater voltage
13 V
Nominal heater current
200 mA
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

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

Pentode

X-ray radiationInterelectrode capacitances
Plate resistance
900000 Ω
Transconductance
0.0018 S
Max plate voltage
250 V
Max screen voltage
125 V
Max plate dissipation
2 W
Max screen dissipation
0.4 W
Max cathode current
15 mA

Remote-cutoff RF pentode; promoted nominal characteristic set uses Va=200/250 V family data and Vg2=100 V.

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

1938 Philips Miniwatt Vacuum Tube Catalog

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Plate voltage

    200 V

    Published table operating point

  • Control-grid bias

    3 V

    Published table operating point

  • Screen voltage

    100 V

    Published table operating point

  • Screen current

    2.6 mA

    Published table operating point

Characteristic

  • Transconductance

    1800000 µS

    Published table characteristic

  • Plate resistance

    900000 ohm

    Published table characteristic

  • Heater/filament voltage

    13 V

    Published heater/filament rating

  • Heater/filament current

    200 mA

    Published heater/filament rating

Capacitance

  • Grid-to-plate capacitance

    0.003 pF

    Published table capacitance

Data set 02

1953 RFT Rundfunk Technik

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Anode voltage

    200 V

  • Screen-grid voltage

    100 V

  • Anode current over control range

    8 to <0.030 mA

  • Screen-grid current over control range

    2.6 to <0.01 mA

  • Transconductance over control range

    1.8 to 0.002 mA/V

  • Cold anode voltage maximum

    550 V

  • Cold screen-grid voltage maximum

    400 V

  • Grid leak resistance maximum

    2.5 MΩ

Capacitance

  • Input capacitance

    6.6 pF

  • Output capacitance

    7.6 pF

Data set 03

195X Tunsgram

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

  • Typical screen voltage

    100 V

  • Typical plate current

    8 mA

  • Maximum no-current anode voltage

    550 V

  • Maximum screen no-current voltage

    400 V

  • Maximum heater-cathode voltage

    125 V

Characteristic

  • Maximum transconductance

    0.0028 A/V

Data set 04

1999 Philips 0-D

Published operating points and test conditions from this source.

SECTION 1

Pentode

Characteristic

  • Maximum transconductance

    2800 µS

Other

  • Typical plate current

    8 mA