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BM10

Guard-ring tetrode electrometer valve with extremely low control-grid current, designed for precision measurement and amplification of exceptionally small electrical currents.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: InternationalOctal
Socket code: IO
Base pins: 8
Nominal heater: 4 V / 25 mA

Description

Guard-ring tetrode electrometer valve with extremely low control-grid current for precision low-current measurements.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: InternationalOctal
Socket code: IO
Base pins: 8
Nominal heater voltage: 4 V
Nominal heater current: 25 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

InternationalOctal - 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

Tetrode

X-ray radiationInterelectrode capacitances

Transconductance: 0.00016 S
Rectifier warm-up time: 45 s

Promoted fields were populated only where the Ferranti sheet maps cleanly to the locked schema; additional ratings and operating values are retained in TUBE_SECTION_PARAMETER.

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 Ferranti

Published operating points and test conditions from this source.

SECTION 1

Tetrode

Other

Anode voltage
4.6 V
Point1
Screen voltage
6 V
Point1
Control-grid voltage
-3 V
Point1
Anode current
275 uA
Point1
Screen current
430 uA
Point1
Anode voltage
6 V
Point2
Screen voltage
4 V
Point2
Anode current
190 uA
Point2
Anode voltage
4 V
Point3
Screen voltage
3 V
Point3
Anode current
100 uA
Point3

Characteristics

Transconductance
160 uS
Point1
Amplification factor
2 ratio
Point1
Transconductance
100 uS
Point2
Amplification factor
1.8 ratio
Point2
Transconductance
90 uS
Point3
Amplification factor
2 ratio
Point3

Capacitance

Output capacitance
6.9 pF
Control-grid to anode capacitance
5 pF
Anode to screen-grid capacitance
1.9 pF