8A1

Brimar English-base RF pentode for high-frequency signal amplification. Manufacturer data specify a 4 V heater, 200 V plate operating point, and 4.0 mA/V transconductance for receiver-type RF service.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: M7A
Base pins: 7
Nominal heater: 4 V / 1 A

Description

English-base RF pentode with 4 V heater, 200 V plate operating point, and 4.0 mA/V transconductance.

Socket description

British/European 7-pin

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: M7A
Base pins: 7
Nominal heater voltage: 4 V
Nominal heater current: 1 A
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: 375000 Ω
Transconductance: 0.004 S

Published ratings and characteristics promoted semantically from source. Repeated identical physical sections are compressed where applicable.

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

1948 Brimar Radio Valve Manual

Published operating points and test conditions from this source.

SECTION 1

Pentode

Other

Plate Voltage
200 V
Plate Current
3.5 mA
Screen Voltage
80 V
Screen Current
0.7 mA
Control Grid Voltage
-1.5 V
Cathode Bias Resistor
200 ohm

Characteristic

Plate Resistance
0.6 Mohm
Transconductance
4000 µS