12BH7A

12BH7A has no equivalent designation confirmed by the archive. Completed sales put the typical price at $30.20 per tube.

The 12BH7A is a miniature, medium-mu twin triode with a T-6½ glass envelope and an E9-1 (Small Button 9-Pin) base, the base type being RETMA 9A. It uses a coated unipotential cathode.

Construction

The 12BH7A incorporates a controlled heater warm-up characteristic, with a warm-up time of 11 seconds. The heater is rated for 12.6 volts at 0.3 amperes for series connection or 6.3 volts at 0.6 amperes for parallel connection. Pin 4 and pin 5 are heater pins, and pin 9 is the heater center-tap. Pin assignments are as follows: pin 1 is the plate of section 2, pin 2 is the grid of section 2, pin 3 is the cathode of section 2, pin 6 is the plate of section 1, pin 7 is the grid of section 1, and pin 8 is the cathode of section 1.

Ratings

For Class A1 amplifier service, each section has a maximum DC plate voltage of 300 volts, a maximum positive DC grid voltage of 0 volts, a maximum negative DC grid voltage of 50 volts, and a maximum plate dissipation of 3.5 watts. In vertical deflection amplifier service, each section has a maximum DC plate voltage of 450 volts, a maximum peak positive pulse plate voltage of 1500 volts, a maximum peak negative grid voltage of 250 volts, and a maximum plate dissipation of 3.5 watts. The maximum DC cathode current for each section is 20 milliamperes; the maximum peak cathode current is 300 milliamperes in Class A1 amplifier service and 70 milliamperes in vertical deflection amplifier service. The maximum DC component of heater positive with respect to cathode voltage is 100 volts, and the maximum total DC and peak heater-to-cathode voltage is 200 volts for either polarity. The maximum grid circuit resistance with fixed bias is 2.2 megohms.

Characteristics

At a plate voltage of 250 volts and a grid voltage of -10.5 volts, each section exhibits an amplification factor of 16.5, an approximate plate resistance of 5300 ohms, a transconductance of 3100 micromhos, and a plate current of 11.5 milliamperes. Each section has a relatively high plate current at low plate voltages and can withstand high pulse voltages. Direct interelectrode capacitances per section are 2.6 micromicrofarads from grid to plate, 3.2 micromicrofarads input, and 0.5 micromicrofarads output for section 1 and 0.4 micromicrofarads output for section 2; plate-to-plate capacitance is 0.8 micromicrofarads.

Applications

The 12BH7A is designed primarily for use as a vertical-deflection amplifier in television receivers. The two sections may be employed in parallel, or as a combined vertical-deflection amplifier and vertical oscillator. It is also suitable for use as the horizontal oscillator in television receivers. The controlled heater warm-up characteristic makes it particularly suited for television receivers employing 600-milliampere series-connected heaters.

Base B9A, viewed from below (the wiring side), pins numbered clockwise from the key. Read from the datasheet's basing table and checked against it automatically — confirm against the original datasheet before wiring.

Per-tube prices from completed sales, 2026-04-28 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 12BH7A, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• 12BH7-A