12BA6

12BA6 is also designated HF93. Completed sales put the typical price at $9.55 per tube.

Description

The 12BA6 is a pentode amplifier with a remote-control grid characteristic, using miniature construction. It has a glass bulb, a 7-pin base, and a coated unipotential cathode. The heater is rated at 12.6 volts and 0.15 ampere AC or DC, and the tube can be operated in any mounting position.

Characteristics

The 12BA6 is characterized by high transconductance and low grid-plate capacitance. The maximum grid-to-plate capacitance (G4 to P) is 0.0035 μμf, the maximum input capacitance is 5.5 μμf, and the maximum output capacitance is 5.5 μμf with shield and 5 μμf without shield.

Ratings

The Tung-Sol datasheet specifies maximum ratings including a plate voltage of 300 volts, a grid #2 voltage of 125 volts, a grid #2 supply voltage of 300 volts, a negative DC grid #1 voltage of 50 volts, a plate dissipation of 3 watts, a grid #2 dissipation of 0.6 watt, and a heater-cathode voltage of 90 volts. The same sheet also lists a maximum peak heater-cathode voltage of 200 volts. The Valvo datasheet for the HF 93 specifies a maximum heater-cathode resistance of 10 kΩ, a maximum heater-cathode voltage of 100 volts, a maximum anode cold voltage of 550 V, a maximum anode voltage of 300 V, a maximum anode dissipation of 3.0 W, a maximum screen grid cold voltage of 550 V, a maximum screen grid voltage of 125 V at an anode current of 11 mA or 300 V at an anode current of 1 mA, a maximum screen grid dissipation of 0.6 W, a maximum cathode current of 18 mA, a maximum grid bias voltage range of 0 to -50 V, and a minimum grid leak resistance of 2 MΩ.

Operating Characteristics

The Tung-Sol datasheet gives typical operating characteristics for the 12BA6 as a Class A1 amplifier. At a plate voltage of 100 volts and grid #2 voltage of 100 volts, the transconductance is 4300 μmhos; at a plate voltage of 250 volts and grid #2 voltage of 100 volts, the transconductance is 4400 μmhos. At a plate voltage of 100 volts, the plate current is 10.8 mA and the grid #2 current is 4.4 mA; at a plate voltage of 250 volts, the plate current is 11 mA and the grid #2 current is 4.2 mA. The approximate grid #1 voltage for a transconductance of 40 μmhos is -20 volts.

The Valvo datasheet gives an operating point for the HF 93 with anode voltage 250 V, screen grid voltage 100 V, grid bias -1 V, anode current 11 mA, screen grid current 4.2 mA, transconductance 4.4 mA/V, and internal resistance 1.5 MΩ. The Valvo datasheet also states that the center pin of the socket is for decoupling grid 1 and anode and must be connected to ground or chassis, and specifies a maximum deviation of the heater current of ±5% from the nominal value of 150 mA.

Equivalence is asserted only where the archive's own literature states it directly, in at least 40 separate documents. Tubes that merely substitute in some circuits are not listed here.

Same design, different filament voltage. Not interchangeable with 12BA6: 6BA6.

Per-tube prices from completed sales, 2026-07-02 to 2026-11-03. Matched pairs and quads are divided out. See the price index for how these move over time.

Original manufacturer datasheets for 12BA6, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• 2. Betriebswerte als HF- oder ZF-Verstärker (filed under HF93)
• TUNG-SOL -