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A horizontal ribbon.

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A horizontal ribbon.

8278
Beam Power Pentode

EIA Base & Outline

EIA Base: 9QB

Substitute Data

Preferred Substitutes ......................... EL503
Source ........................................ GE - 1973

Application

Beam power pentode intended as a AF power amplifier.

Mechanical Data

Bulb .......................................... T-9
Base Type ..................................... Magnoval
Maximum Overall Height ........................ 3.38 In.
Maximum Seated Height ......................... 3.00 In.
Maximum Diameter .............................. 1.18 In.
EIA Base ...................................... 9QB

Electrical Data

Heater Voltage ................................ 6.3 V
Heater Current ................................ 1.2 A

Direct Interelectrode Capacitances (approx)

Pentode
Input ......................................... 22.5 pf
Output ........................................ 13.5 pf
Grid to Plate ................................. 1.7 pf

Maximum Ratings (Design Center Values)

Pentode
Plate Voltage ................................. 300 V
Grid No. 3 Voltage ............................ 300 V
Plate Dissipation ............................. 25 W
Grid No. 2 Dissipation ........................ 4.0 W

Characteristics and Typical Operation

Class A Amplifier
Plate Voltage ................................. 250 V
Grid No. 2 Voltage ............................ 250 V
Grid No. 1 Voltage ............................ -12.5 V
Plate Resistance (approx) ..................... 7.3K Ω
Transconductance .............................. 24000 µMho
Plate Current ................................. 100 mA
Grid No. 2 Current ............................ 8.0 mA

Push Pull Class AB1 Amplifier
Plate Voltage ................................. 265 V
Grid No. 2 Voltage ............................ 265 V
Grid No. 1 Voltage Derived from
Cathode Bias Resistor ...................... 56 Ω
Plate Current ................................. 200 mA
Grid No. 2 Current ............................ 16.0 mA
Power Output (approx) ......................... 40 W

A horizontal ribbon.

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A horizontal ribbon.

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Mon, 15 Aug 2022 18:11:19 -0700