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UF86

Series-heater low-level audio-frequency pentode designed for resistance-capacitance-coupled AF voltage amplification. Mullard documentation also provides triode-connected operation, but sensitive audio voltage gain is its primary function.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: B9A
Socket code: B9A
Base pins: 9
Nominal heater: 12.6 V / 100 mA

Description

Series-heater low-level audio-frequency pentode for resistance-capacitance coupled AF voltage-amplifier service.

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: B9A
Socket code: B9A
Base pins: 9
Nominal heater voltage: 12.6 V
Nominal heater current: 100 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

B9A - 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: 2500000 Ω
Transconductance: 0.002 S
Max plate voltage: 300 V
Max screen voltage: 300 V
Max plate dissipation: 1 W
Max screen dissipation: 0.2 W
Max cathode current: 6 mA

Published valve ratings and characteristics promoted where applicable; additional data 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

1958 Mullard Receiving Tubes

Published operating points and test conditions from this source.

SECTION 1

Pentode

Application

Application
Low-noise audio voltage amplifier / microphone preamplifier
Triode-connected operation
Published
TriodeConnection

Data set 02

1963 Mullard

Published operating points and test conditions from this source.

SECTION 1

Pentode

Capacitance

Output capacitance
5.3 pF
Input capacitance
3.8 pF
Grid-to-plate capacitance maximum
0.05 pF

Characteristics

Plate voltage
200 V
Screen-grid voltage
140 V
Plate current
3 mA
Screen-grid current
600 uA
Control-grid voltage
-2 V
Transconductance
2000 uS
Plate resistance
2.5 MOhm
Screen-to-control-grid amplification factor
38 ratio

Other

Stage gain
115 ratio
RCCoupledAFAmplifier;Vb=200V;Ra=100k
Output voltage
38 Vrms
RCCoupledAFAmplifier;Vb=200V;Ra=100k