NJ7P SQL Tube Database Query

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25A6
Power Amplifier Pentode

EIA Base & Outline

Substitute Data

Substitutes ................................... 25W6
Source ........................................ RCA RC-13 - 1937

Application

Metal type used in output stage of ac/dc receivers. Requires octal socket and may be mounted in any position.

Mechanical Data

Bulb .......................................... MT-8
Base Type ..................................... Small Wafer Octal 7-Pin
EIA Outline ................................... 8-6
EIA Base ...................................... 7S

Electrical Data

Heater Voltage ................................ 25 V
Heater Current ................................ 0.3 A

Characteristics and Typical Operation

Class A Amplifier
Plate Voltage ................................. 180 V
Grid No. 2 Voltage ............................ 135 V
Grid No. 1 Voltage ............................ -20 V
Grid No. 1 Voltage Derived from
Cathode Bias Resistor ...................... 440 Ω
Amplification Factor .......................... 100
Plate Resistance (approx) ..................... 40K Ω
Transconductance .............................. 2500 µ
Plate Current ................................. 38 mA
Grid No. 2 Current ............................ 7.5 mA
Load Resistance ............................... 5K Ω
Power Output (approx) ......................... 2.75 W

Class A Amplifier
Plate Voltage ................................. 135 V
Grid No. 2 Voltage ............................ 135 V
Grid No. 1 Voltage ............................ -20 V
Grid No. 1 Voltage Derived from
Cathode Bias Resistor ...................... 440 Ω
Amplification Factor .......................... 85
Plate Resistance (approx) ..................... 35K Ω
Transconductance .............................. 2450 µ
Plate Current ................................. 37 mA
Grid No. 2 Current ............................ 8 mA
Load Resistance ............................... 4K Ω
Power Output (approx) ......................... 2 W

Class A Amplifier
Plate Voltage ................................. 95 V
Grid No. 2 Voltage ............................ 95 V
Grid No. 1 Voltage ............................ -15 V
Grid No. 1 Voltage Derived from
Cathode Bias Resistor ...................... 625 Ω
Amplification Factor .......................... 90
Plate Resistance (approx) ..................... 45K Ω
Transconductance .............................. 2000 µ
Plate Current ................................. 20 mA
Grid No. 2 Current ............................ 4 mA
Load Resistance ............................... 4.5K Ω
Power Output (approx) ......................... 0.9 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

Wed, 29 Mar 2023 06:54:47 -0700