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6BD4A

Sharp-cutoff beam triode for high-voltage shunt regulation; 27 kV maximum plate voltage, 25 W dissipation, μ 1650.

Directly heatedCold cathodeCommon cathodeDissimilar

Sections: 1
Base: 6BD4
Socket code: B7G
Base pins: 7
Nominal heater: 6.3 V / 600 mA

Description

The 6BD4A is a sharp-cutoff beam triode for high-voltage, low-current shunt-regulator service, not a general-purpose RF receiving triode. It uses an indirectly heated 6.3 V, 0.6 A cathode, with maximum DC plate voltage 27 kV, maximum unregulated supply voltage 55 kV, maximum DC plate current 1.5 mA and maximum plate dissipation 25 W. Published amplification factor is 1650. RCA and Sylvania document two shunt-regulator circuit examples, peak heater-cathode limits of ±180 V, and an X-ray shielding warning above approximately 16 kV plate voltage.

Socket description

Miniature 7-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base: 6BD4
Socket code: B7G
Base pins: 7
Nominal heater voltage: 6.3 V
Nominal heater current: 600 mA
Parallel heater voltage: -
Parallel heater current: -
Series capable: No

6BD4 - 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

Triode

X-ray radiationInterelectrode capacitances

Amplification factor: 1650
Max plate voltage: 27000 V
Max plate dissipation: 25 W
Max cathode current: 1.5 mA

Sharp-cutoff beam triode for HV shunt regulation. Maximum DC plate 27 kV, unregulated supply 55 kV, plate current 1.5 mA, plate dissipation 25 W. Amplification factor 1650. Heater-to-cathode peak voltage ±180 V. Grid-to-plate capacitance 1.0 pF; output capacitance ≤0.04 pF. Grid circuit resistance maximum 4 MΩ when supply equivalent resistance ≥8 MΩ; otherwise see manufacturer curve. Effective grid-plate transconductance 138 or 116 µmhos depending on circuit example, not intrinsic gm. X-rays possible above approximately 16 kV; shielding may be needed.

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

1950 Sylvania

Published operating points and test conditions from this source.

SECTION 1

Triode

Characteristic

Cathode Coated Unipotential low current supplies. The 6BD4A
Sylvania descriptive OCR fragment; not an electrical value.
Cathode Coated Unipotential low current supplies. The 6BD4A
Heater or filament current
600 mA
Nominal heater current 600 mA; corrected OCR error
DC Voltage . .o . 29800 36300 Volts PRODUCTS INC.
29800 to 36300 V
Unregulated supply DC voltage for two typical shunt-regulator examples
Equivalent Resistance . 8 8 Megohms
8 Megohm
Equivalent Resistance . 8 8 Megohms
Equivalent Resistance . 1000 1000 Ohms APRIL 1955
1000 Ohms
Equivalent Resistance . 1000 1000 Ohms APRIL 1955
For Load Current of 0 Ma 10_?’5 pa
Typical DC plate current at zero load: see RCA original, OCR uncertain.
For Load Current of 0 Ma 10_?’5 pa
For Load Current of 1 Ma 100 pa
Typical DC plate current at 1 mA load: see RCA original, OCR uncertain.
For Load Current of 1 Ma 100 pa
For Load Current of 0 Ma . 20000 27000 Volts
20000 to 27000 V
Regulated output voltage at 0 mA load: example A 20000 V, example B 27000 V
For Load Current of 1 Ma . 19700 26500 Volts
19700 to 26500 V
Regulated output voltage at 1 mA load: example A 19700 V, example B 26500 V
voltage or 16,000 volts, whichever is less.
16000 V
X-ray shielding warning: above approximately 16000 V plate voltage; corrected OCR 16 V
Amplification Factor
1650
Amplification factor, sharp-cutoff beam triode
Heater-Cathode Voltage
180 V
Maximum peak heater-to-cathode voltage ±180 V, both polarities
Grid Circuit Resistance
4 MΩ
Maximum grid circuit resistance when unregulated supply equivalent resistance >=8 MΩ; otherwise consult curve
Transconductance
138 µmho
Effective grid-plate transconductance, circuit example A, 29,800 V unregulated supply
Transconductance
116 µmho
Effective grid-plate transconductance, circuit example B, 36,300 V unregulated supply

Other

Heater Voltage . 6.3 Volts age rating and plate dissipation
6.3 V
Heater Voltage . 6.3 Volts age rating and plate dissipation
DC Plate Voltage. . . . 27000 Volts Max.
27000 V
DC Plate Voltage. . . . 27000 Volts Max.
Unregulated D C Supply Voltage . 55000 Volts Max.
55000 V
Unregulated D C Supply Voltage . 55000 Volts Max.
D C Plate Current 1.5 Ma Max.
1.5 mA
D C Plate Current 1.5 Ma Max.
Plate Dissipation . 25 Watts Max.
25 W
Plate Dissipation . 25 Watts Max.

Data set 02

195X General Electric Essential Characteristics

Published operating points and test conditions from this source.

SECTION 1

Triode

Other

Maximum unregulated DC supply voltage
55000 V
HighVoltageShuntRegulator
Maximum DC plate current
1.5 mA
HighVoltageShuntRegulator
Maximum plate dissipation
25 W
HighVoltageShuntRegulator