12ax7 Tube Datasheet

| May 23, 2013 | 3 Comments

12ax7-base-pinoutThe 12ax7 is a miniature high-mu twin triode, each section of which has an individual cathode connection. It is especially suited for use in resistance-coupled voltage amplifiers, phase inverters, multivibrators, and numerous industrial-control circuits where high voltage gain is desired. A center-tapped heater permits operation of the tube from either a 6.3-volt or a 12.6-volt heater supply.

Key data and drawings are shown below, or you can download the 12ax7 Datasheet in PDF format. All information is deemed reliable but not guaranteed.

Base Pinout Diagram and Physical Dimensions


Terminal Connections

Pin 1Plate #2
Pin 2Grid #2
Pin 3Cathode #2
Pin 4Heater
Pin 5Heater
Pin 6Plate #1
Pin 7Grid #1
Pin 8Cathode #1
Pin 9Heater Center Tap

General Characteristics

CathodeCoated Unipotential
Heater Voltage: AC or DC12.6V series / 6.3V parallel
Heater Current0.15A series / 0.30A parallel
EnvelopeT - 6 1/2, Glass
BaseE9-1, Small Button 9-pin
Mounting PositionAny

Direct Interelectrode Capacitances

With Shield*
Without Shield
Grid to Plate, Each Section1.7pF (uuF)1.7pF (uuF)
Input, Each Section1.8pF (uuF)1.6pF (uuF)
Output, Section 11.9pF (uuF)0.46pF (uuF)
Output, Section 21.9pF (uuF)0.34pF (uuF)
* with external shield (RETMA 315) connected to cathode of section under test

12ax7 Maximum Ratings – Design-Center Values, Each Section

Plate Voltage300 volts
Positive DC Grid Voltage0 volts
Negative DC Grid Voltage50 volts
Plate Dissipation1.0 watts
Heater-Cathode Voltage
- Heater Positive with respect to Cathode180 volts
- Heater Negative with respect to Cathode180 volts

Characteristics and General Operation – Class A1 Amplifier, Each Section

Plate Voltage100 volts250 volts
Grid Voltage-1 volt-2 volts
Amplification Factor100100
Plate Resistance, approximate80,000 ohms62,500 ohms
Transconductance1250 micromhos1600 micromhos
Plate Current0.5 mA1.2 mA

Category: Kit Building 101

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