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6550C

6550-family high-power beam tetrode for audio output service, combining substantial plate dissipation with high-current capability for powerful Class-AB amplifier stages.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: -
Socket code: IO
Base pins: 8
Nominal heater: 6.3 V / 1.6 A

Description

Glass-envelope beam power pentode for ultralinear audio-frequency power amplification, designed as a direct 6550 replacement with improved reliability and audio performance.

Socket description

International Octal

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: -
Socket code: IO
Base pins: 8
Nominal heater voltage: 6.3 V
Nominal heater current: 1.6 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

Beam Power

X-ray radiationInterelectrode capacitances

Transconductance: 0.0095 S
Max plate voltage: 680 V
Max screen voltage: 400 V
Max plate dissipation: 35 W
Max screen dissipation: 6 W
Max cathode current: 175 mA

Section values promoted from published characteristics and maximum ratings.

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

199X Svetlana

Published operating points and test conditions from this source.

SECTION 1

Beam Power

Characteristic

Voltage (AC or DC) 5.7 6.3
6.9 V
SourcePage1-2
Current
1.6 A
SourcePage1-2
base sleeve and heater
18.5 pF
SourcePage1-2
base sleeve and heater
12.5 pF
SourcePage1-2
Grid no.1 to plate (max)
1.1 pF
SourcePage1-2

Other

DC plate voltage
680 V
SourcePage1-2
Grid no.2 DC (screen) voltage
400 V
SourcePage1-2
Grid no.1 (control) voltage
-300 V
SourcePage1-2
DC cathode current
175 mA
SourcePage1-2
Plate dissipation
35 W
SourcePage1-2
Grid no.2 (screen) dissipation
6 W
SourcePage1-2
DC plate voltage
400 V
TypicalOperation
Grid no.2 DC (screen) voltage
225 V
TypicalOperation
Grid no.1 DC (control) voltage
-22 V
TypicalOperation
Peak AF grid no.1 (control) voltage
22 V
TypicalOperation
Zero-signal plate current
87 mA
TypicalOperation
Max signal plate current
105 mA
TypicalOperation
Max signal grid no.2 (screen) current
18 mA
TypicalOperation
Load resistance
3000 ohms
TypicalOperation
Signal output at 5% distortion
12 W
TypicalOperation
Screen Voltage =
250 V
TypicalOperation