NJ7P SQL Tube Database Query

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8278
Beam Power Pentode

EIA Base & Outline

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 µ
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

If you are uncertain about the EIA designator for a particular tube please use the "Index" button to list all the tubes in the database. You can click on the designator for the closest tube.

(c) 1994-2021 by William A. Beech, NJ7P

Sat, 25 Jun 2022 09:40:51 -0700