6HG8

6HG8 is also designated ECF86.

General Description

The 6HG8 is a miniature triode-pentode tube intended for use as a VHF oscillator and frequency changer in color television equipment. It has a directly heated cathode and is designed for parallel heater supply. The tube uses a T-6 1/2 miniature envelope with a button 9-pin base (E9-1), basing 9MP, and outline 6-2. Maximum diameter is 0.875 inches, maximum seated height is 1.937 inches, and maximum overall height is 2.187 inches.

Heater and Ratings

The heater is rated at 6.3 volts and draws 340 mA. Maximum heater-cathode voltage is 200 volts total DC and peak with the heater negative with respect to the cathode; with the heater positive, the DC limit is 100 volts and the total DC and peak limit is 200 volts.

For the triode section, maximum plate voltage is 125 volts, maximum plate dissipation is 1.9 watts, maximum cathode current is 16.5 mA, and maximum grid No. 1 circuit resistance is 0.5 megohm. For the pentode section, maximum plate voltage is 250 volts, maximum grid No. 2 voltage is 250 volts, maximum plate dissipation is 2.2 watts, maximum grid No. 2 dissipation is 0.55 watts, and maximum cathode current is 20 mA. The pentode grid No. 1 circuit resistance is limited to 0.25 megohm with fixed bias and 0.5 megohm with cathode bias. The DC or peak AC voltage between the pentode control grid and cathode must not exceed 30 volts; for the triode control grid and cathode, the limit is 50 volts.

Electrical Characteristics

The triode section has an amplification factor of 17, a plate resistance of 3100 ohms, and a transconductance of 5500 micromhos. The pentode section has an amplification factor of 70, a plate resistance of 350,000 ohms, and a transconductance of 12000 micromhos.

Interelectrode capacitances for the triode section are: grid-to-plate, 2.0 pF; input, 2.4 pF; output, 1.1 pF. For the pentode section: grid No. 1 to plate, 0.020 pF; input, 6.0 pF; output, 3.5 pF; grid No. 1 to grid No. 2, 1.7 pF. Coupling capacitances between sections are: triode grid to pentode plate, 0.014 pF; pentode grid No. 1 to triode plate, 0.014 pF; pentode plate to triode plate, 0.01 pF; pentode grid No. 1 to triode grid, 0.14 pF.

Notes on Alternate Data

The Mazda datasheet, which refers to the tube as ECF86, lists some differing figures. It gives a heater current of 390 mA, an envelope outline of 22-2, and a base designation of 9C12 (noval). The Mazda sheet lists maximum anode voltage for the pentode as 250 V, maximum grid No. 2 voltage as 150 V, maximum anode dissipation as 2 W, maximum grid No. 2 dissipation as 0.5 W, maximum cathode current as 18 mA, maximum grid No. 1 circuit resistance as 0.5 megohm, and maximum heater-cathode voltage as 100 V. It also specifies maximum anode voltage at zero current as 550 V and maximum grid No. 2 voltage at zero current as 550 V. For the triode section, the Mazda sheet gives maximum anode voltage as 125 V, maximum anode dissipation as 1.5 W, maximum cathode current as 15 mA, and maximum grid circuit resistance as 0.5 megohm. Capacitance values in the Mazda sheet are: pentode input, 5.8 pF; pentode output, 3.5 pF; triode input, 2.4 pF; triode output, 1.1 pF; triode grid-to-plate, 2 pF. The Mazda sheet assigns pin 1 as cathode and grid No. 3 of the pentode, cathode of the triode, and internal shield; pin 7 as triode anode; pin 8 as pentode anode; and pin 9 as grid No. 2.

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 6HG8, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• 6HG8/ECF86
• MAZDA (filed under ECF86)