4FS7

Triode plus sharp-cutoff frame-grid RF pentode for frequency-changing service to approximately 220 MHz.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 2
Base: -
Socket code: B9A
Base pins: 9
Nominal heater: 4.6 V / -

Description

Combined triode and sharp-cutoff frame-grid RF pentode for frequency-changing service to 220 MHz.

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: -
Socket code: B9A
Base pins: 9
Nominal heater voltage: 4.6 V
Nominal heater current: -
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

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances

Max plate voltage: 125 V
Max plate dissipation: 1.5 W
Max cathode current: 15 mA

Published Mullard/Ferranti ratings and characteristics promoted where applicable; additional electrical values retained as parameters.

Section 2

Pentode

X-ray radiationInterelectrode capacitances

Plate resistance: 350000 Ω
Transconductance: 0.012 S
Amplification factor: 70
Max plate voltage: 250 V
Max screen voltage: 150 V
Max plate dissipation: 2 W
Max screen dissipation: 0.5 W
Max cathode current: 18 mA

Published Mullard/Ferranti ratings and characteristics promoted where applicable; additional electrical values retained as parameters.

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

1963 Mullard

Published operating points and test conditions from this source.

SECTION 1

Triode

Application

Application
Frequency changer to 220 MHz

Capacitance

Pentode-to-triode plate capacitance
0.14 pF
Pentode plate-to-triode grid capacitance
0.014 pF
Pentode grid1-to-triode plate capacitance maximum
0.01 pF
Pentode grid1-to-triode grid capacitance maximum
0.01 pF
Grid-to-cathode-and-heater capacitance
2.4 pF
Plate-to-cathode-and-heater capacitance
1.1 pF
Plate-to-grid capacitance
2 pF

Other

Heater-cathode voltage maximum
100 V
Plate voltage maximum
125 V
Plate dissipation maximum
1.5 W
Cathode current maximum
15 mA
Grid circuit resistance maximum
500 kohm

SECTION 2

Pentode

Capacitance

Plate-to-grid1 capacitance
0.012 pF
Output capacitance
3.5 pF
Grid1-to-grid2 capacitance
1.7 pF

Other

Plate voltage maximum
250 V
Plate dissipation maximum
2 W
Screen voltage maximum
150 V
Screen dissipation maximum
0.5 W
Cathode current maximum
18 mA
Grid circuit resistance maximum - cathode bias
500 kohm
Grid circuit resistance maximum - fixed bias
250 kohm
Frequency-changer plate voltage
190 V
Frequency-changer screen supply voltage
150 V
Frequency-changer screen resistor
18 kohm
Frequency-changer grid1 resistor
100 kohm
Frequency-changer plate current
8.5 mA
Frequency-changer screen current
2.7 mA
Oscillator voltage RMS
2.3 V
Conversion conductance
450 uS

Characteristics

Plate voltage characteristic
170 V
Screen voltage characteristic
150 V
Plate current characteristic
10 mA
Screen current characteristic
3.3 mA
Transconductance
12000 uS
Plate resistance minimum
350 kohm
Inner amplification grid1-to-grid2
70
Grid1 voltage characteristic
-1.2 V