6CH6

6CH6 is also designated EL821.

The 6CH6 is an indirectly heated high-slope pentode intended for use as a video amplifier valve, and is also useful in AF power output stages where high sensitivity is required. It is suited for use as a triode-connected cathode follower amplifier having a low output impedance.

Construction

The 6CH6 is of miniature construction mounted in a T6 ½ bulb and is fitted with a B9A (Noval) base. The suppressor grid g3 is brought out separately to a pin, but it consists of beam confining plates rather than a grid as such. Pin 2 is the control grid g1, pin 3 is the cathode k, pins 4 and 5 are the heater connections, pin 7 is the anode a, pin 8 is the screen grid g2, and pin 9 is the suppressor grid g3. Pins 1 and 6 are internal connections.

Ratings

The heater of the 6CH6 is intended for use in parallel with those of other valves in AC operated equipment. The heater voltage is 6.3 volts, with a nominal heater current of 0.75 ampere. The maximum DC heater-cathode potential is 90 volts. The maximum overall length is 2-5/8 inches, the maximum diameter is 7/8 inch, and the maximum seated height is 2-3/8 inches.

In pentode operation, the maximum anode voltage is 275 volts, the maximum screen voltage is 275 volts, the maximum anode dissipation is 12 watts, and the maximum screen dissipation is 2.5 watts. The maximum DC cathode current is 65 mA, and the maximum peak cathode current is 1.5 amperes. The maximum control grid circuit resistance is 100,000 ohms, which may be increased to 220,000 ohms if cathode bias is employed. The maximum bulb temperature is 250 degrees Celsius. The duration of peak cathode current flow must not exceed 2 microseconds and must not be greater than 5% of the duty cycle. The control grid is not designed to withstand any appreciable dissipation, so no positive DC grid current should be allowed to flow. The 6CH6 is not recommended for use as a Class B or C amplifier, or as a frequency multiplier.

When the 6CH6 is triode connected (g2 to a, g3 to k), the maximum anode voltage is 275 volts, the maximum anode dissipation is 12.5 watts, the maximum DC cathode current is 65 mA, the maximum peak cathode current is 1.5 amperes, the maximum grid circuit resistance is 100,000 ohms, and the maximum bulb temperature is 250 degrees Celsius.

Characteristics

The input capacitance of the 6CH6 is 14 pF, the output capacitance is 5.0 pF, the grid to anode capacitance is 0.25 pF maximum, and the heater to cathode capacitance is 7.0 pF. The Brimar datasheet gives the 6CH6 as having a mutual conductance of 14.5 mA/V and an amplification factor of 26.4 in one operating condition.

Applications

The Brimar datasheet states that due to its high slope, the 6CH6 is very suitable for a cathode follower stage where a low output impedance is required. Triode connected, the output impedance varies between 60 and 70 ohms depending on the value of cathode resistor employed. With a 250 volt HT supply, the cathode resistor should not be less than 100 ohms, as the bias would then be insufficient. The Brimar datasheet also states that the 6CH6 is well suited for wide band amplifier applications due to its high slope, relatively low output capacity, and high standing anode current, and gives characteristic curves for the 6CH6 with the control grid positive, useful for pulse modulator applications. The Brimar datasheet gives a power output of 1.8 watts with a peak grid to grid input voltage of 9.0 volts and total harmonic distortion of 1% for the 6CH6 in a push-pull AF output stage.

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.

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.

Original manufacturer datasheets for 6CH6, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• BRIMAR
• CAPACITANCES (measured without an external shield) (filed under EL821)