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Voltage Radio Detector Converter ·Pentode-Triode

6X8A

Combined triode-pentode for oscillator, mixer, frequency-converter, RF, or IF service in television, communications, or mobile receivers.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 2
Base: 9AK
Socket code: B9A
Base pins: 9
Nominal heater: 6.3 V / 450 mA

Description

6X8A is a TriodePentode vacuum tube documented in the RCA Receiving Tube Manual. The supplied excerpt was reviewed for heater data, section arrangement, maximum ratings, electrical characteristics, interelectrode capacitances, typical operating conditions, and stated applications.

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: 9AK
Socket code: B9A
Base pins: 9
Nominal heater voltage: 6.3 V
Nominal heater current: 450 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

9AK - Terminal pinout

Electrical assignments shared by every tube using this base designation.

Terminal	Section	Connection	Evidence
PIN11G3	A	G3 — Suppressor Grid EIA chart transcription, manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9AK
PIN22G1	B	G1 — Control Grid EIA chart transcription, manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9AK
PIN32P	B	P — Plate (Anode) EIA chart transcription, manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9AK
PIN4H	—	H — Heater EIA chart transcription, manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9AK
PIN5H	—	H — Heater EIA chart transcription, manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9AK
PIN6K	A	K — Cathode EIA chart transcription, manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9AK
PIN71G1	A	G1 — Control Grid EIA chart transcription, manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9AK
PIN81G2	A	G2 — Screen Grid EIA chart transcription, manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9AK
PIN91P	A	P — Plate (Anode) EIA chart transcription, manufacturer confirmation pending	Unverified EIA Base Connections, printed page 131, 9AK

Section ratings

2 physical sections, each with unique specifications.

Section 1

Triode

X-ray radiationInterelectrode capacitances

Plate resistance: 6000 Ω
Transconductance: 0.0065 S
Amplification factor: 40
Max plate voltage: 275 V
Max plate dissipation: 1.7 W

Section 2

Pentode

X-ray radiationInterelectrode capacitances

Plate resistance: 300000 Ω
Transconductance: 0.0055 S
Max plate voltage: 275 V
Max screen voltage: 275 V
Max plate dissipation: 2.3 W
Max screen dissipation: 0.45 W

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

1961 Tung Sol

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Heater voltage
6.3 V
Nominal
Heater current
450 mA
Nominal
Plate voltage
125 V
ClassA
Grid 1 voltage
-1 V
ClassA

Characteristic

Plate current
12 mA
ClassA
Transconductance
6500 uS
ClassA
Plate resistance
6000 ohm
ClassA
Amplification factor
40
ClassA
Heater warm-up time
11 s
ControlledWarmup

SECTION 2

Pentode

Other

Heater voltage
6.3 V
Nominal
Heater current
450 mA
Nominal
Plate voltage
125 V
ClassA
Screen voltage
125 V
ClassA
Grid 1 voltage
-1 V
ClassA

Characteristic

Plate current
9 mA
ClassA
Screen current
2.2 mA
ClassA
Transconductance
5500 uS
ClassA
Plate resistance
300000 ohm
ClassA
Zero-bias transconductance
5700 uS
ClassA

Data set 02

1966 Tung Sol Electronic Tubes 2 of 4

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Plate voltage
125 V
ClassA
Grid #1 voltage
-1 V
ClassA
Plate current
12 mA
ClassA
Heater warm-up time
11 s
BothSections

Characteristic

Transconductance
6500 uS
Plate resistance
6000 ohm
Amplification factor
40

Capacitance

Grid-to-plate capacitance
1.7 pF
Input capacitance
3 pF
Output capacitance
1.4 pF

SECTION 2

Pentode

Other

Plate voltage
125 V
ClassA
Grid #2 voltage
125 V
ClassA
Grid #1 voltage
-1 V
ClassA
Plate current
9 mA
ClassA
Grid #2 current
2.2 mA
ClassA

Characteristic

Transconductance
5500 uS
Plate resistance
300000 ohm

Capacitance

Grid-to-plate capacitance
0.02 pF
Input capacitance
5 pF
Output capacitance
2.6 pF