When the tube is operated below the knee of its Ia-Ua characteristic the screen-grid series resistor Rg2 must have a minimum value of 2.2kOhm to avoid the occurrence of Barkhausen oscillations.

Quand le tube fonctionne au-dessous du genou de sa charactéristique Ia-Ua la résistance série de la grille écran Rg2 doit avoit une valeur de 2,2kOhm au minimum pour éviter la formation d'oscillations de Barkhausen.

Values are given for nominal new tubes. On designing a line output circuit it has to be taken into account that due to tube spread and deterioration during life the current may be reduced by 25%.

Ils sont données des valeurs de tubes moyens neufs. Quand on étudie un circuit de sortie de déviation horizontale, il faut tenir compte du fait que par suite des tolérances du tube et de la dégradation en service les courants donnés peuvent se diminuer de 25%.

This tube has a center-tapped filament and can be used with both sections in parallel, at half the rated heater voltage, and twice the current. Using series connection of the filament, it is essential to keep the voltages at each section equal. This can be achieved by means of a shunting resistor tied in parallel to the second filament section allowing to bypass the cathode current of the first section. At parallel connection, the filament center-tap and grid no.3 are tied to the negative terminal, the filament ends (f-, f+) are tied to the positive terminal of the heater supply.

Alimentation du filament en série (Uf, If) ou en parallèle (Uf/2, Ifx2). Lorsque les filaments sont branchés en série, il est essentiel d'egaliser la chute de tension aux bornes de chaque section. A cet effet, une résistance doit êntreplacée en parallèle sur la 2ème section afin d'écouler le courant cathodique de la 1ère section. Lorsque les filaments sont branchés en parallèle, les broches avec le point milieu du filament et grille n° 3 sont connectées au pôle négatif et les broches f- et f+ au pôle positif.

With external shield.

Mesurées avec blindage.

This tube is designed to resist shocks and vibrations encountered in mobile and aircraft equipment, or in electronic appliances used in the industry. The heater is able to withstand a sequence of at least 5000 cycles of intermittent operation.

Ce tube a été conçu pour résister aux chocs et vibrations auxquels peuvent être soumis les équipements mobiles employés en particulier dans l'Aéronautique ou les appareils électroniques utilisés dans l'Industrie. Le filament est apte à supporter un minimum de 5000 allumages et extinctions successifs.

Typical characteristics of the oscillator section with grid No.1 (g1) as oscillator grid and grid No.2 (g2) als oscillator plate (anode).

Caractéristiques typiques de la partie oscillatrice (grille g1, anode g2).

Operation characteristics with current saving circuit (not suitable for the short-wave range).

Caractéristiques d'utilisation en montage économisateur (ne convient pas pour ondes courtes).

Dark heater.

Ruggedized premium type, intended for applications where dependable performance under shock and vibration is paramount. Especially suited for operation under conditions encountered in mobile and aircraft service.

This tube is manufactured in three variants, specified by a suffix in the type designator: with forced-air cooling (suffix L), water cooling (suffix W), and vapor cooling (suffix V).

This tube is manufactured in two variants, specified by a suffix in the type designator: with forced-air cooling (suffix L), and water cooling (suffix W).

With vapor cooling.

With water cooling.

Oscillator for industrial applications. Plate voltage from mains transformer (self rectification).

Suitable for water and air cooling.

This tube is manufactured in two variants, specified by a suffix in the type designator: with forced-air cooling (suffix L), and vapor cooling (suffix V).

Metal-ceramic tube with coaxial electrodes.

Reliable vacuum tube, specifically designed for aircraft and industrial applications where freedom from early failure, long average service life, and uniform operating characteristics are extremly important.

The grid-No.2 voltage Ug2 is obtained preferably from a separate source, or from the plate-voltage supply with a voltage divider, or through a series resistor Rg2 of the value shown.

The grid-No.1 voltage Ug1 is obtained preferably from a fixed supply (fixed-bias method) or by grid-No.1 (grid-leak) resistor Rg1 of the value shown.

Grid return to center-tap of AC filament supply. If DC supply is used, return grid to negative filament terminal and decrease bias approximately 3 to 4 volts.

For applications critical as to matching of the two units.

For applications critical as to microphonics, noise, and hum.

For applications critical as to microphonics.

Plate shows no color when the tube is operated at maximum CCS ratings.

Intended for use as a relay tube in equipment on ships for automatically announcing SOS signals. To meet the special requirement of such service, this tube features an ip-eg characteristic having suitable slope and minimized variation between tubes. (Available only through Radiomarine Corporation of America, 75 Varick Street, New York, N.Y.)

Grid return to center-tap of AC filament supply (Suppressor/Beam Plates and Control Grid). If DC supply is used, return grids to negative filament terminal and decrease bias by 1.75 volts.

For cathode-bias operation a minimum cathode-resistor by-pass condenser of 25 µF is recommended to minimize hum, particularly where this tube is followed by high-gain stages. When a 25 µF condenser or larger is used, the voltage difference between heater and cathode is not critical, but it should be kept as low as possible. If less than a 25 µF condenser is used, positive or negative biasing of the heater with respect to the cathode is required, but the bias value chosen for minimum hum should be within the range of +5 to +50 volts or –5 to –50 volts.

For applications requiring continuity of service.

Grid bias voltage obtained from a fixed supply Ug, by grid resistor Rg, by cathode resistor Rk, or by combination methods.

The grid-bias voltage Ug is obtained preferably from a fixed supply (fixed-bias method) or by grid-leak resistor Rg of the value shown.

For AC filament supply. If DC is used, the stated grid-bias voltage should be decreased by 1.75 volts.

For oscillator applications requiring unusually stable characteristics.

For applications critical as to uniformity of characteristics.

Plate shows no color when the tube is operated at maximum CCS or ICAS ratings.

Screen-grid voltage obtained from a fixed supply Ug2 or from the plate-voltage supply with a voltage divider, or through a series resistor Rg2 of value shown. Under key-up conditions the maximum grid-No.2 voltage should not exceed the value of Ug2o. A series screen resistor should not be used except where the tube is employed as a buffer amplifier and is not keyed.

Plate shows a barely perceptable red color when the tube is operated at maximum CCS ratings.

Plate shows no color when the tube is operated at maximum CCS ratings, and shows a barely perceptable red color at maximum ICAS ratings.

Plate shows cherry-red color when the tube is operated at maximum CCS ratings, and orange-red color at maximum ICAS ratings.

Forced ventilation from fan directed at middle and upper portions of bulb is required for continuous key-down conditions in class-C telegraph service and is recommended for other services at frequencies of 30 MHz or higher.

To avoid VHF oscillations it is required to mount a grid stopper resistor of at least 1000 ohms close to the control-grid terminal, and/or to insert a screen-grid series resistor of at least 100 ohms.

When using two tubes in parallel or in a class-A or class-AB push-pull circuit, a separate cathode-bias resistor is required for each tube, however, a common cathode resistor may be used in a class-AB push-pull circuit at a quiescent (zero-signal) plate current of less than or equal to 45 mA per tube.

This type has a rigid structure to reduce microphony. It is particularly suitable as a DC amplifier due to its stable characteristics.

Glass tube with straight-side (S) bulb.

This type has flexible leads for wiring directly into the circuit.

Pin (approximately) at crest of AF cycle with 100% modulation.

Ug1 obtained from the resistor Rg1 of value shown, a cathode resistor, fixed supply or a combination of methods. Ug2 obtained from a separate source, from the anode voltage supply via a potential divider or through a series resistor Rg2 of value shown. A series resistor should be used only in a circuit in which the valve is not keyed. Ig1 is subject to wide variation dependent upon the impedance of the load circuit.

This valve is for use in battery operated receivers. The two diodes operate on a separate portion of the filament, with the result that in operation the two diodes and the triode are independent of each other. The special feature of this valve, is that it has been designed for battery economy, and due to the exceptionally low filament consumption is therefore particularly recommended for use in battery portable receivers. The bulb is of small dimensions and metallised. The valve is fitted with a British Octal Base.
This valve is recommended for performing the simultaneous functions of detection, automatic volume control and audio frequency amplification. The anode current of each diode starts at different potentials. In use, therefore, Pin No.1 should be connected to the negative terminal of the Low Tension battery, and for normal purposes the Diode No.2 should be employed as a detector diode. The diode load resistance should be returned to the negative end of the filament, whilst Diode No.1 should be used as an Automatic Volume Control diode. In this way an extra delay voltage of the order of 1.4 volt is obtained. When the valve is used in conjunction with an H.F. valve requiring an initial bias of 1.5 volts, a total delay voltage of about 2.9 volts is obtained. It is recommended that the diode load resistance should not be less than 0.5 megohm. When the triode is used as a resistance-coupled L.F. amplifier an anode load of the order of 100,000 ohms should be used. When used with a parafed transformer circuit, a lower resistance may be necessary, but this will depend upon the transformer design.

Fixed bias is recommended and the control-grid resistor should not exceed the specified value of Rg1. Ug2 obtained preferably from a separate source or from the anode supply using a voltage divider.

With internal neutralisation for frequencies up to 200 MHz.

Bulb temperatures Tb < 0°C result in a reduced life-time expectancy and significant changes in electrical characteristics. It is recommended to use a supply voltage Ub > 200V. In designing equipment to be used over a wide temperature range the use of "constant current operation" (high supply voltage Ub with a high anode series resistor RaL) is recommended.

Provided that the wiring is carefully laid out, it is possible, in spite of the high amplification, to ensure complete stability of the amplifier. If difficulties are encountered, a neutralizing capacitor may be connected between anode and grid of one of the triodes, a suitable value for all frequencies being about 4 pF.

Grounded-cathode circuit with bias Ug1 obtained from a cathode resistor Rk in the negative return of the supply voltage.

When the full AF amplification over both sections is to be used, the value of the resulting AC resistance at the triode grid should not exceed 0.3 megohms.

Operation of this tube as a power rectifier is not recommended.

The permissible anode dissipation rating is a function of the grid to cathode resistance and circuit employed.

When used in cascade, section 1 should be employed as the input stage, as this section has the lower grid hum level of 3µV r.m.s. Measured with a low pass filter (cut-off = 350 c/s). If either side of the heater ist earthed rather than the centre tap, the maxiumum value of hum would be of the order of 10µV r.m.s.

For conventional operation the grid bias is obtained by means of a resistor Rk in the cathode circuit, this resistor being capacitively by-passed for audio frequency currents.

Appreciably lower distortions will be obtained when the cathode by-pass capacitor is omitted but an increased drive voltage will be required. It will be noted that, when using negative feedback by this method, the optimum load resistance is roughly 7% lower than with no feedback.

Operation with RC filtering for screen. The following data is given in view of the modern tendency to dispense with smoothing chokes in the H.T. smoothing circuit. Under such conditions, in order to keep the ripple voltage (approx. 10 volts max.) and the ripple current within the safe limits of the average electrolytic capacitor, it is necessary to use a combination of two 16µF capacitors in parallel. This permits the anodes of the output valves to be fed from the reservoir capacitor and the screen grids and pre-amplifier supplies via an RC filter.

In order to prevent parasitic oscillations in the output stage it is advisable to include resistors of the values stated below in the screen grid and control grid leads, as close to the valve holder as possible.
Screen grid circuit: 47 ohms 0.5 watt.
Control grid circuit: 1000 ohms 0.5 watt.

All the measurements given in this publication were taken with a sinusoidal input voltage. Under normal conditions of speech and music input, the full drive values of Ia and Ig2 will be smaller.

The push-pull stages are intended for speech and music amplification, and it is unwise to drive the valves fully with a continuous sine wave. In applications where there is a risk of over-running the screens, as for instance in amplifiers which are often overloaded or which are occasionally mis-matched, a common limiting resistance of 2000 ohms in the lead to the two screens is a suitable precaution.
As, however, this would result in an appreciable loss in the maximum available power output, a better solution is to connect a 200-230 V 25 watt electric lamp in series with the screens. At the low screen currents which normally occur, the resistance of such a lamp is low, but increases rapidly with increasing current. In this manner the sreens are protected against overloads at the cost of only about 10% loss in maximum power output.

The figures quoted for output power Pout are for the power delivered by the valve or valves into the output transformer. The power obtained in a load connected in the secondary circuit of the transformer will be slightly smaller owing to losses in the transformer.

For "On-Off" control applications involving long periods of operation under cutoff conditions.

Up to 300 MHz the inductance of the heater leads is sufficiently low to allow the heater pins to be earthed capacitatively.

The input power is reduced at the higher frequencies in order to keep within the rated maximum anode dissipation.

Higher values of capacitance CkL than indicated may be used, but the effective plate-supply impedance Ra should be increased to prevent exceeding the maximum rating for peak plate current Ia (PK).

Coupling capacitors (Cg1, Ca) should be adjusted to give the desired frequency response. Rg2 should be adequately bypassed (Cg2).

The diode is located at the negative end of the filament.

In application where the tube is required to operate for any extended period at heater voltages in excess of 28 volts, a resistor should be inserted in series with the heater supply voltage and the heater.

When operating or testing one section only, the grid of the other section must be biased to –40 volts.

These ratings may be realized, provided the DC plate circuit resistance does not exceed 50 ohms per section.

Any unnecessary grid circuit resistance provides additional self bias and is not recommended if rated output is desired.

In order to make a tube providing good power output with only 28 volts plate supply, it is necessary to provide more cathode power than is customary in power output tubes. This results in a high operating temperature which should be considered in the selection of the tube socket and the placement of parts.

Maximum power level when driven by a continuous sine-wave signal, in order not to exceed the maximum allowable screen-grid dissipation.

With external cylindrical shield of 22.2 mm inner diameter.

With external cylindrical shield of 30 mm inner diameter.

Uf applied across the two filament sections in parallel, between pin fm,g3 and pins f+ and f– connected together. Ug1 referred to fm,g3.

Uf applied across the two filament sections in series, between pin f+ and pin f–. Ug1 referred to f–.

For series operation of the filament sections, a shunting resistor must be connected across the section between pins f- and fm,g3 to bypass any cathode current 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 between pins f+ and f-.

With external cylindrical shield of 0.405 inch inner diameter connected to cathode.

With external shield of 0.405 inch inner diameter connected to heater

The No.2 grid shall not be used for control purposes.

With external cylindrical shield of 22.5 mm inner diameter connected to grid.

In order to achieve long life time and stability of electrical characteristics, biasing by high-value cathode resistor and positive grid-supply voltage is recommended.

Operated as triode: screen grid g2 tied to plate (anode), suppressor grid g3 tied to cathode.

Operated as triode: screen grid g2 and suppressor grid g3 tied to plate (anode).

For operation at less than maximum ratings.

This tube is specially designed to assure dependable life and reliable service under the exacting conditions encountered in mobile and aircraft applications. Features include mechanical ruggedization and a heater-cathode construction designed to withstand many-thousand cycles of intermittent operation.

Improved-reliability long-life type with tight tolerances and cathode free from interface. The cathode establishes no interface even in cases where the heated tube is operated without plate current over lengthy periods.

This tube will maintain its emission and freedom from excessive cathode interface resistance even after long periods of operation under cutoff conditions.

At maximum ratings, it is necessary that at least one surface of the shield be blackened.

Grid leak Rg1g3 and any g1/g3 circuit is referenced to the f+/g6 terminal.

This tube is designed for long life computer service and other 'on-off' control applications requiring long periods of operation under cut-off conditions.

Values for each unit, with both units operating.

Driver stage is required to supply tube losses an RF-circuit losses. The driver stage should be designed to provide an excess of power above the indicated values to take care of variations in line voltage, components, initial tube characteristics, and tube characteristics during life.

All voltages are referred to the negative filament terminal f–.

Premium tube for use in equipment requiring exceptional stability and reliability under severe environmental conditions.

26.5 mm maximum bulb diameter (24.5mm typical).