6977

6977 is also designated DM160.

Description

The 6977 is a filamentary, high-vacuum subminiature indicator triode with a glass bulb. It has a grid-shaped plate coated with a phosphor that emits bright blue-green light proportional to the plate current. The tube has a filamentary cathode and can be operated in any mounting position.

Construction

The 6977 has 4 tinned leads of 0.016 inch diameter. The Philips datasheet specifies gold-plated leads. Directly soldered connections to the leads must be at least 5 mm from the seal, and any bending of the leads must be at least 1.5 mm from the seal.

Ratings

The Tung-Sol datasheet specifies a filament voltage of 1.0 volts, a filament current of 30 mA, and limits of applied filament voltage of 0.95–1.05 volts. The Philips datasheet specifies a filament voltage of 1.0 V ± 5%, and states the heater can be supplied by AC or DC with parallel supply. Limiting values from the Philips datasheet include a maximum anode voltage of 100 V (also given as 65 V in a separate specification), a maximum grid voltage of 0 V, a maximum negative grid voltage of 50 V, a maximum anode current of 750 μA, and a maximum grid resistor of 1.0 MΩ with a minimum grid resistor of 0.1 MΩ.

Characteristics

At a plate voltage of 50 volts and grid voltage of 0 volts, the Tung-Sol datasheet gives a plate current of 440 μA, a transconductance of 450 μmhos, and an amplification factor of 30. With a grid supply voltage of 0 volts and a grid resistor of 100 kΩ, the plate current is 580 μA and light output is 6 millicandles. With a grid supply voltage of +3.0 volts, plate current is less than 5 μA and light output is not visible. Interelectrode capacitances are 1.8 pF grid-to-plate, 1.0 pF grid-to-filament, and 1.1 pF plate-to-filament.

Applications

The 6977 is designed for applications in electronic computers, where its small size, low energy requirements, high sensitivity, and freedom from noise make it useful in combination with transistorized circuits. The Philips datasheet describes it as a directly heated voltage indicator for use in transistorized computers. The Philips datasheet states that a considerable improvement in contrast can be obtained by using a light filter of cellulose acetate with a thickness of about 0.3 mm, shifting the spectral light curve from the green towards the blue region.

Reliability and Life

The 6977 is controlled to military standards for high reliability. The Philips datasheet describes it as having special quality, long life, and shock resistance of about 500 g. Under life test conditions of Vf = 1.0 V, Va = 50 V, Vbg = 0 V, and Rg = 100 kΩ, the Philips datasheet specifies a life expectancy of 10,000 hours.

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.

Original manufacturer datasheets for 6977, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• PHILIPS (filed under DM160)
• TUNG-SOL -