Section I grounded-cathode circuit, section II grounded-grid circuit.

Ultra-linear connection with grid No.2 tapped at 50% plate signal voltage of the primary winding.

Additive mixer.

With zero-impedance driver and perfect regulation, plate-circuit distortion does not exceed the indicated value. In practice, plate-voltage regulation, screen-voltage regulation, and grid-bias regulation, should not be greater than 5%, 5%, and 3%, respectively.
Driver stage should be capable of supplying the grids of the Class AB stage with the specified peak values at low distortion. The effective resistance per grid circuit of the Class AB stage should be kept below 500 ohms and the effective impedance at the highest desired response frequency should not exceed 700 ohms.

Fixed-bias values up to 10% of each typical screen voltage can be used without increasing distortion.

Ruggedized Premium Tube, employs a Micanol barrier base which absorbs less moisture and reduces the chance of voltage breakdown between adjacent pins.
Especially suited for use in industrial and military equipment which may be subjected to severe shock and vibration, such as airborne equipment.

Triode Connection: grid No.2 connected to anode through 100 ohms resistor.

Recommended ratings for operation with negligible anode current fluctuations.

Glass tube with dome-top tubular bulb.

Incandescent lamp of 550V/68W.

It is essential that the screen-grid voltage be constant if this output is to be obtained.

This tube is also suitable for use as a mixer or oscillator at low frequencies, but it is not recommended for low-level audio-frequency applications unless the heater voltage is obtained from a DC source.

For maximum voltage conditions. With series screen resistor and cathode bias.

When a fixed screen voltage is used, a sharp-cutoff characteristic is obtained. When a screen resistor is used, an extended-cutoff characteristic is obtained which may be utilized in applications where the gain is controlled by variation of the grid bias. In RF and IF stages, the suppressor should be connected directly to ground to minimize feedback. The cathode bias resistor should be adjusted to give the indicated plate current.

Primarily intended for operation from a six-volt storage battery. Grid volts are measured from negative end of DC-operated filament. If the filament is AC-operated, the tabulated values of grid bias should each be increased by 4.0 volts and be referred to the mid-point of filament.

The tube must be operated only using self bias (generated by cathode-bias resistor).

Fixed-bias operation is not recommended.

The second heater pin (base pin No.4) should be preferably grounded or be connected to the lowest potential with reference to ground or chassis.

The tube may be used without special considerations due to hum and microphonics in circuits delivering a power output of 50 mW for an input voltage of >= 10 mV(rms) at grid No.1.

Ug1 obtained from fixed supply or by cathode resistor.

.......

.......

Supressor should be connected to the mid-point of filament circuit operated on AC, or to the negative end of the filament operated on DC.

Ug2 obtained from a separate source, or from the plate-voltage supply with a voltage divider, or through a series resistor of the value shown. Series screen resistor should be used only where the tube is employed as buffer amplifier and is not keyed.

Ug1 obtained from fixed supply, grid resistor, or cathode resistor. When a preceding stage is keyed, sufficient fixed bias must be used to maintain the plate current at a low value when the key is up.

Glass-metal tube with coaxial-electrode structure.

Deflecting plate ps2 has to be connected to anode a.

With post-acceleration.

This type is not recommended for high-gain, audio-amplifier applications because undesirable hum may be encountered if the heater is not DC operated.

As a class A1 amplifier, this type may be operated either as a pentode or triode, as shown under tabulated data.
The grid-No.2 voltage for this tube operated as a pentode may be obtained from a potentiometer or bleeder circuit across the B-supply device. Due to the grid-No.2-current characteristics of this tube, a resistor in series with the high-voltage supply may be employed for obtaining the grid-No.2 voltage, provided the cathode-resistor method of bias control is used. This method, however, is not recommended if the high-voltage B-supply exceeds 300 volts.

As a radio-frequency amplifier, this type may be used particularly in applications where the RF signal applied to grid No.1 is relatively low, that is, of the order of a few volts. In such cases either grid-No.2 or grid-No.1 voltage (or both) may be varied to control the receiver volume. When larger signals are involved, a remote-cutoff amplifier tube should be employed to prevent the occurrence of excessive cross-modulation and modulation-distortion.

The grid-No.2 and cathode bypass capacitors (Cg2, Ck), and blocking capacitors (Ca) have been chosen to give output voltages at 100 cps (f1) which are equal to 0.7 of the mid-frequency value. For any other value of f1, multiply the of value cathode and bypass blocking capacitors by 100/f1. In the case of capacitor Ck, the values shown in the charts are for an amplifier with DC heater excitation. When AC is used, depending on the character of the associated circuits, the voltage gain, and the value of f1, it may be necessary to increase the value of Ck to minimize hum disturbances. It may be desirable to operate the heater at a positive voltage from 15 to 40 volts with respect to the cathode.

Plate shows an orange-red color when the tube is operated at maximum CCS ratings.

May be operated in vertical position only, base up or down.

Triode Connection: Grid No.1 tied to grid No.2 (High-µ connection).

Plate shows an cherry-red color when the tube is operated at maximum CCS ratings.

Natural cooling by radiation and convection.

This type has two separate oxide-coated unipotential cathodes each of which is connected to its respective heater. Plate circuit return should be made to the center tap of the heater transformer.

The cathodes should be allowed to come up to operating temperature before plate current is drawn from the tube. For average conditions the delay is approximately the value indicated by tf.

This type has an anti-microphonic construction and its heater is designed to reduce hum.

In order to reduce the hum to a minimum the centre tap of the transformer winding which feeds the heaters should be connected to the chassis. The impedance between cathode and chassis should be as small as possible (<40 Ohm).

Power Output Pout and Harmonic Distortions k are measured at fixed bias and therefore represent the power output available during the reproduction of speech and music. When a sustained sine wave is applied to the control grid the bias across the cathode resistor will readjust itself as a result of the increased anode and screen-grid currents. This will result in a reduction of power output of approximately 10%.

With Rk unbypassed.

With Rk bypassed.

Suitable for continuous sine wave drive.

For RF applications it is recommended that both g1 pins should be strapped together and each g3 pin be connected separately to the chassis.

Operating as a grounded-grid RF amplifier, the use of resonant tank circuit is recommended in order to obtain greatest linearity and power output. For best results with a single-ended amplifier it is suggested that the cathode tank circuit operate at the indicated value of Qin or more.

The tube can be biased by any convenient method: from fixed supply Ug, by grid resistor Rg, by cathode resistor Rk, or by combination methods. However, the use of a grid resistor is preferred because the bias is automatically adjusted as the load on the circuit varies.

When this tube is used in the final amplifier or a preceding stage of a transmitter designed for break-in operation and oscillator keying, a small amount of fixed bias must be used to maintain the plate current at a safe value.

Short (0.200") leads.

Adjust screen-grid voltage Ug2 to obtain the indicated plate current Iaa at maximum power output.

It is recommended to use a fixed grid-leak resistor Rg1 for each unit and a common adjustable resistor connected in series to adjust the plate current for optimum conditions.

Grid bias voltage obtained from a fixed supply Ug1, by grid-No.1 resistor Rg1 (grid leak), by cathode resistor Rk, or by combination methods.

Screen-grid voltage obtained from a separate source Ug2, from the plate supply Ub through a voltage divider, or through a series resistor Rg2 of value shown. The grid-No.2 voltage must not exceed 600 volts under key-up conditions.

Tetrode Connection - Grids No.2 and No.3 tied together.

Grid bias voltage obtained from a fixed supply Ug1 of good regulation or from suitably bypassed cathode resistor Rk.

-

Input capacitance Cin and output capacitance Cout apply to grounded-grid circuit.

Capacités montage grille à la masse.

Noise Figure measured at power matching.

Special-quality tube intended for use in critical industrial and military applications in which operational dependabilty is of primary importance. Features of the tube include a high degree of mechanical strength and a heater-cathode construction capable of withstanding many-thousand cycles of intermittent operation. When used in on-off control applications, the tube will maintain its emission capabilities after long periods of operation under cutoff conditions.

For series-filament arrangement, filament voltage is applied between pins f+ and f-, the grid-No.1 voltage is referred to pin f-.
For parallel-filament arrangement, filament voltage is applied between pin fm and f+ and f- connected together, the grid-No.1 voltage is referred to pin fm.
For series operation of the filament sections, a shunting resistor must be connected across the section between pins f- and fm to bypass any cathode current in this section which is in excess of the rated maximum per section. When other tubes in a series-filament arrangement contribute to the filament current of this tube, an additional shunting resistor may be required across the entire filament (pins f+ and f-).

For series-filament arrangement, filament voltage is applied between pins f+ and f-. Grid voltage is referred to pin f-.
For parallel-filament arrangement, filament voltage is applied between pin fm+ and pins f+ and f- connected together. Grid voltage is referred to pins f+ and f- tied together.
For series operation of the filament sections, a shunting resistor must be connected across the section between pins f- and fm+ to bypass excess cathode current in this section. The value of the shunting resistor should be adjusted to make the voltage across the shunted section equal to the voltage across the section between pins fm+ and f+. When other tubes in a series-filament arrangement contribute to the filament current of this tube, an additional shunting resistor may be required across the entire filament (pins f+ and f-).

Measured under pulsed operating conditions.

Used as RF Linear Amplifier with catode resistance. The drive power is determined with a 50 ohm resistive input circuit. Increasing the resistance in the cathode circuit decreases the zero-signal plate current and increases the drive power required.

The intermodulation distortion level does not deteriorate with decreasing drive voltage.

The grid bias of this tube may be obtained by a series resistor in the negative supply lead only (semi-self biasing with grounded cathode).
To avoid parasitic VHF oscillations it is recommended to insert a stopper resistor of at least 1000 ohms directly at the control grid, and/or a resistor of at least 300 ohms at the screen grid. When utilizing full tube gain self-excited oscillations may occur, which can be avoided by shielding the lower part of the tube, e.g. by a socket with a metal sleeve connected to ground. Care should be taken that the DC plate-supply voltage will not significantly drop below the screen-grid voltage, since the cathode current will flow completely or partially to the screen grid causing excessive overload.

Ratings of an average new tube.

Cathode terminal No.7 (input) is to be earthed via the cathode resistance, cathode terminal No.3 (output) is to be connected to the earthside of the output circuit via a condenser.

To avoid parasitic VHF oscillations it is essential to insert a stopper resistor of at least 1000 ohms directly at the control grid, and/or a resistor of at least 100 ohms at the screen grid.

The tube must be operated only using self bias (generated by cathode-bias resistor) respective semi-self bias (by a series resistor in the negative supply lead). In push-pull circuits separate cathode resistors are required.

Values are measured under equal-amplitude two-tone test conditions to simulate practical operation with voice and music signals. The indicated power Pout represents the power output of a continuous sine-wave signal with the amplitude of the sum of each individual amplitude of the two-tone signal. The figure of harmonic distortions k is obtained by extrapolating the distortion formula to the case of a two-tone drive signal.

Cathode potential is obtained on the filament center tap when using AC supply, respective on the negative filament terminal at DC supply. In the latter case the value of grid bias voltage has to be decreased by 3.5 volts.

Fixed bias operation is recommended only when the plate and screen dissipation is less than 70 percent of the design-center maximum ratings.

This tube features one large zirconium-coated graphite anode, with three separate grid-cathodes structures. This anode, while lighter in weight than similar metal anodes, remains warp free during life and provides one of the best gas "gettering  means known. The anode is supported by ceramic insulators. The use of these insulators and the hard glass envelope permit the tube to be outgassed at high temperatures during the manufacturing exhaust process. This allows the tube to be run at high temperatures during operation, without the evolution of harmful gas from the tube parts.
Massive cathodes provide adequate emission current reserve. Gold-plated molybdenum wires are employed in the rugged grid structure. The tube mount is built on a rugged button stem, and is supported from the bulb by means of flexible metal vibration snubbers.

Rk: minimum cathode resistance per cathode leg or that resistance necessary to provide 10% of the grid bias voltage, whichever is greater.

Applied for short interval (two seconds maximum) so as not to damage tube.

The effective resistance of the grid circuit should be below 500 ohms, and the effective impedance should not exceed 700 ohms at the highest response frequency required.

Spot distortions (astigmatism) may be corrected by applying an appropriate voltage between g4/a and the average plate potential of the cathode-side deflecting plates (pk).

By applying an appropriate voltage between the anode a and the average deflecting plate potential the astigmatism may be corrected. The internal resistance of the voltage source has to be relatively low to avoid deviations of the correcting voltage caused by beam current changes.

24mm maximum bulb diameter.

Advantageous in applications that require low hum and microphonic output.

Parallel heater arrangement is recommended for use in high-gain, resistance-coupled-amplifier applications such as in the preamplifier stages of phonographs, microphones, and tape recorders. With closely paired, electrostatically shielded heater leads, a hum-balance control is unnecessary when the center tap of the heater transformer is connected to ground. In applications where the heater-transformer winding does not have a center-tap, a 100-ohm hum-balancing potentiometer should be connected across the heater leads with the slider connected to ground.

Cathode bias by common cathode resistor Rkk.

Grid voltages are given with respect to the mid-point of filament operated on AC. The grid and plate return should be brought to a mid-tap of the filament winding. If DC is used, each stated value of grid voltage should be decreased by one half of the peak filament voltage (0.7xUf) and the circuit returns made to the negative filament terminal.

Grid bias may be obtained from a separate C-supply or by means of the voltage drop in a resistor Rk connected in the negative plate return lead.

Grid bias should be obtained by use of the voltage drop in a resistor Rk connected in the negative plate return lead (self-biasing method).

The filament is intended for operation from a 6-volt storage battery. A fixed or variable resistor of suitable value is required to reduce the battery voltage to 5.0 volts across the filament terminals at the socket.

The filament in this tube is designed for operation with three No.6 dry-cells connected in series to give 4.5 volts. If storage battery operation is preferred, a 4-volt storage battery may be used. In any case, a filament rheostat should be provided to maintain the voltage applied to the filament within the stated range Uf.

The filament may be operated conveniently from dry-cells, from a single lead storage-cell, or from a air-cell battery. For dry-cell operation, a filament rheostat may be used together with a permanently installed voltmeter to insure the proper filament voltage. For operation from a 2-volt lead storage-cell no filament resistor is required. Operation with an air-cell battery requires a fixed resistor in the filament circuit. This resistor should have a value such that with a new air-cell battery, the voltage applied across the filament terminals will not initially exceed 2.15 volts.

The heater-cathode is designed for DC operation. The heater operates satisfactorily from a 6-volt automobile storage battery without rheostat or fixed resistor despite the voltage fluctuations during the charge and discharge periods. The heater may be operated in series with other heaters in receivers designed to operate from DC house mains. Regardless of the number of heaters connected in series, the current in the heater circuit should be adjusted to 0.3 ampere for the normal supply voltage.

Mit normierter Anheizzeit tf = 20 Sekunden im Mittel.

Controlled heater warm-up characteristic with average warm-up time tf = 20 seconds.

Mit normierter Anheizzeit tf = 17 Sekunden im Mittel.

Controlled heater warm-up characteristic with average warm-up time tf = 17 seconds.

For use with 12-cell storage-battery supply.

Screen grids g2 and g4 are tied to plate (anode), and control grid g3 is tied to cathode.

Control grid is grid No.3 (g3), oscillator grid is grid No.1 (g1). The characteristics shown are with separate excitation, corresponding very closely with those in a self-excited oscillator circuit operating with zero-bias.

Low-loss phenolic base.

For use with 25-volts storage-battery supply, heater series connection is permissible when the center tap of the heater string is always maintained at half the battery voltage, by means of a center tap of the battery, or by the center tap of a voltage divider tied in parallel to the battery. The total resistance of the voltage divider including the parallel-connected heater strings has to be less than or equal to 25 ohms. If an odd number of tubes is used, the heater of the missing tube must be replaced by a resistor of 170 ohms, ±5%.

For use in preamplifier stages.

For use in AF output and RF transmitting stages.

Glass type with extraction knob.

Mit normierter Anheizzeit tf = 8 Sekunden im Mittel.

Controlled heater warm-up characteristic with average warm-up time tf = 8 seconds.

This tube is a special low-noise and low-microphonic type with constant characteristics over full lifetime. It is especially suited for use in microphone preamplifiers and similar applications.

Both anodes/plates tied together.

Two tubes operating in parallel.

Two tubes operating in push-pull.