6BL8 Generic

The 6BL8 is a 9-pin small signal medium-mu triode and a sharp cutoff pentode originally designed for frequency changer and timebase of black and white TV's, it got used in a some amplifiers like the Playmaster 116/7 with the pentode as gain following the volume control and the triode as a split-load phase inverter.

Base: 9DC

Electrical Data

Heater Voltage  6.3 V
Heater Current  0.45 A
Maximum Heater-Cathode Voltage
Heater Positive with Respect to Cathode
DC Component 100 V
Heater Negative with Respect to Cathode
DC Component 100 V

Direct Interelectrode Capacitances (approx)

Pentode
Input 5.5 pf
Output 3.8 pf
Grid to Plate 0.025 pf

Triode 
Input 2.5 pf
Output 1.8 pf
Grid to Plate 1.5 pf

Maximum Ratings (Design Center Values)

Pentode
Plate Voltage 250 V
Grid No. 2 Voltage 175 V
Plate Dissipation 1.7 W
Grid No. 2 Dissipation 0.5 W
Cathode Current 14 mA
Grid No. 1 Circuit Resistance
Fixed Bias 0.5M ohm
Self Bias 1M ohm

Triode
Plate Voltage 250 V
Plate Dissipation 1.5 W
Cathode Current 14 mA
Grid No. 1 Circuit Resistance
Fixed Bias 0.5M ohm
Self Bias 0.5M ohm

Characteristics and Typical Operation

Triode Class A Amplifier
Plate Voltage 100 V
Grid No. 1 Voltage -2 V
Amplification Factor 20
Transconductance 5000 µ
Plate Current 14 mA

Pentode Class A Amplifier
Plate Voltage 170 V
Grid No. 2 Voltage 170 V
Grid No. 1 Voltage -2 V
Plate Resistance (approx) 400K ohm
Transconductance 6200 µ
Plate Current 10 mA
Grid No. 2 Current 2.8 mA

With thanks to NJ7P database.

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