KyteLabs InfoBase - Electron Tubes & Valves Data Last modified: 2021-06-05 (20303)


A.2 Hinweise und Bemerkungen
Notes and Remarks

The heater voltage should be reduced at operating frequencies above 300MHz: f=300...400MHz Uf=5.75V, f=400...500MHz Uf=5.5V.
Fixed-frequency oscillator using grounded-grid triode 6S11D enclosed in silver-plated metal case.
This tube probably had never come to mass production. It appeared only in the 1968 edition of the Telefunken Pocket Book.
These ratings apply to zero ohms plate-supply impedance and zero ohms effective grid-circuit impedance.
These ratings apply to 1000 ohms plate-supply impedance and 516 ohms effective grid-circuit impedance at 400 Hz for class B stage in which the effective resistance per grid circuit is 500 ohms, and the leakage reactance of the coupling transformer is 50 millihenries. The driver stage should be capable of supplying the grids of the class B stage with the specified values at low distortion.
The heater voltage should be reduced at operating frequencies above 300MHz: f=300...400MHz Uf=25.3V, f=400...500MHz Uf=24.3V.
Ruggedized structure capable of withstanding severe shock and vibration.
With cavity resonator.
Life expectancy of minimum 1000 hours, having self-contained source of hydrogen.
At about 180° phase shift between Ua~ and Ug1~.
Three-phase half-wave rectifier circuit.
Single-phase full-wave rectifier circuit.
Three-phase bridge rectifier circuit.
Negative-control characteristic.
The available output is limited by the anode dissipation under two-tone test conditions. Greater output may be possible if the peak to mean value of the modulation waveforms permit greater input power without exceeding the dissipation rating.
Power output includes transferred driving power, while indicating pure tube effieciency.
Die Eingangsleistung Pin ist die rückgekoppelte Leistung.
Pin is driving power by feedback.
In order to prevent parasitic oscillation, it is desirable to use a grid stopper resistor mounted close to the tubeholder. In class AB1 audio circuits this may have a value up to 10 kOhm.
In order to prevent parasitic oscillation, it is desirable to use a grid stopper resistor of about 100 Ohm mounted close to the tubeholder. In radio-frequency circuits an anode stopper consisting of a 100 Ohm 1/4 Watt resistor overwound with 2 1/2 turns of 18 s.w.g. copper wire may also be necessary. The usual practice of using a single chassis point for all earth returns should always be adopted in r.f. equipment.
RF Oscillator for industrial applications supplied by three-phase rectifier.
Tungsten filament type cathode.
RF Oscillator for industrial applications. Plate voltage supplied by three-phase half-wave rectifier circuit without filter, measured by moving-coil voltmeter.
RF Oscillator for industrial applications. Plate voltage supplied by single-phase full-wave rectifier circuit without filter. Voltages and currents are average values.
RF Oscillator for industrial applications. Plate voltage supplied by three-phase half-wave rectifier circuit without filter. Voltages and currents are average values.
Oxide-coated filament type cathode.
Full-wave rectifier with capacitor input to filter.
Full-wave rectifier with choke input to filter.
This tube has two separate heaters that can be used parallel or serial connected. The indicated ratings are with both heaters in parallel.
With gliding screen-grid voltage.
Triode grid tied to grid no.3 of the heptode.
It is recommended to use cathode bias.
Grid voltage are given with respect to the mid-point of filament operated on AC. If DC is used, each stated value of grid voltage should be decreased by 7 volts and the circuit returns made to the negative end of the filament.
Convection cooling.
Precaution: X-ray shielding may be required to give protection against excessive radiation.
The screen s is provided to shield grid and cathode from the high anode voltage. It is recomended to connect the screen directly to ground, with a minimum lead inductance.
Glass type with external metal shield and extraction knob.
Glass tube with tubular (T) bulb and plate cap.
Improved-reliability long-life type with tight tolerances, rugged shock and vibration tolerant contruction, and cathode free from interface.
Measured values at end of life time.
ICAS operation invariably results in decrease of life time. Several tubes may be connected in parallel to increase power output. The load impedance RaL has to be reduced accordingly, by factor 2 when using two tubes for example.
RF amplifier - telegraphy or FM telephony.
RF amplifier - telegraphy.
Voltage divider R1/R2 with bypass capacitor.
Driven by voice or music level adequate to swing the grid to the point where it starts to draw current (Ig1=300nA).
Harmonic distortions measured with fixed grid bias.
High-µ triode connection: screen grid g2 and suppressor grid g3 are tied to the control grid g1.
The envelope of this type is coated with a water-repellent layer to avoid arcing even at high ambient humidity.
Pure-metal cathode.
The heater of this type should be inserted into the series-connected heater string in such a manner that a minimum resistance of 100 ohms is present between any heater pin and any power-line terminal used by the heater string. This resistance may consist of the heaters of other tubes.
The protective grid s between filament and cathode should be connected via a resistor of 330 ohms to either of the heater pins f, whichever has the lowest potential difference to one of the two power-line terminals.
Ultra-linear connection with grid No.2 tapped at 43% plate signal voltage of the primary winding.
A bias adjustment range of ±25% should be available for each tube (valve).
The screen grid g2 is connected by a 22 ohms resistor to the plate.
Ionically heated cathode.
Used in vibrator-type B-supply units. Filters may be necessary to eliminate objectionable noise.
If the actual cathode current is less than the maximum rating while operating as an oscillator or amplifier, life expectancy may be increased by reducing the heater voltage.
To avoid circumferential oscillations it is recommended to use rotationally symmetrical plate resonators at frequencies above 5 GHz.
Class-C radio-frequency oscillator with pulsed plate voltage.
With nickel matrix-type cathode for improved pulse current-handling capability.
Grid-keyed pulse-mode amplifier.
Due to low electrode spacings and relatively high field strengths, short-time arcing between the electrodes may occur especially in the grid-keyed pulse-mode operation. To avoid damage to the tube it is highly recommended to insert a protective resistor into the plate circuit, limiting the arcing current to a maximum of 10-fold the permissible rating.
For use in mobile communications equipment operating from 6-cell storage-battery systems. Heater voltage range 12 to 15 volts, momentary excursions from 11 to 15 volts.
DC grid-No.1 voltage varied to obtain the nominal plate current indicated.
Power output and DC currents are average values.
Ug2 and Ug1 obtained preferably from separate well-regulated sources.
Glass-metal pencil tube with sturdy coaxial-electrode structure.
Matrix-type, oxide-coated, unipotential cathode.
Single-tube, grid-driven coaxial-cavity class-C-amplifier circuit.
Because the cathode is subjected to considerable back bombardement as the frequency is increased with resultant increase in temperature, the heater voltage should be reduced depending on operating conditions and frequency to prevent overheating the cathode and resultant short life.
Bias voltage obtained from a fixed supply, or by a grid-No.1 resistor of value shown at Rg1.
Each plate of each section. Other plate of same section grounded.
The heater should be connected with Pin No.4 closest to the ground end of the heater string.
Test condition only. Operating conditions must not exceed the design center rating.
Contact-potential bias by Rg3.
Instantaneous values. Measurement of this characteristic must be made by a method involving a recurrent wave form, such that the tube is not damaged by plate or grid No.2 dissipations in excess of the maximum ratings.
Shorter bulb with exhaust tip at bottom.
For series filament arrangement, filament voltage is applied between pins f+ and f-. The grid-No.1 voltage is referred to pin f-, and grid-No.3 is connected to pin f-.
For parallel filament arrangement, filament voltage is applied between pin fm and pins f+ and f- connected together. The grid-No.1 voltage is referred to pin fm, and grid-No.3 is connected to pin fm.
Filament may be connected in either parallel or series arrangement.
Ug1 obtained from a fixed supply, or grid-No.1 resistor Rg1, or cathode resistor Rk.
Ug2 obtained from a separate source, or from the plate voltage supply with a voltage divider. Series screen resistor Rg2 of value shown should be used only where the tube is employed as a buffer amplifier and is not keyed.
Because of the high bulb temperature it is necessary to mount the tube directly on the chassis by means of a metal clamp (ZE 1100) to ensure sufficient conduction cooling.
For tube protection, it is essential that sufficient resistance be used in the plate supply circuit, the grid-No.2 supply circuit, and the grid-No.1 supply circuit so that the short-circuit current is limited to 0.5 ampere in each circuit.
Plate dissipation averaged over any interval not exceeding 10 milliseconds. Care should be used in determining the plate dissipation. A calculated value based on rectangular pulses can be considerably in error when the actual pulses have a finite rise and fall time. Plate dissipation should preferably be determined by measuring the bulb temperature under actual operating conditions; then, with the tube in the same socket and under the same ambient-temperature conditions, apply to the tube sufficient DC input to obtain the same bulb temperature. This value of DC input is a measure of the plate dissipation.
Used as RF Linear Single-Sideband Amplifier, suppressed carrier.
Pout: Peak-Envelope Power (PEP). Distortion level referred to the amplitude of either of the tones, at full drive; also highest distortion encountered at any driving level up to full drive.
Half-indirect heated cathode.
Glass type with metal cap and extraction knob.
Since exceeding the recommended filament voltage will result in evaporation of thorium, rapidly damaging the tube and making it useless, it is required to exactly observe the following rules:
On each tube has been noted its specific filament voltage. That each tube of the receiver will be heated correctly, it is advisable to use a separate variable resistor (rheostat) for each tube. When heating from a storage batterie of 4 volts resp. a triple-cell dry batterie, the necessary rheostat resistance is about 40 ohms. In order to adjust the proper filament voltage, a voltmeter of sufficient resolution (at least ±0.1 volts) should be used. If no voltmeter is available, turn on the rheostat as far as a reddish shine appears on the top of the tube indicating the glowing filament. Now the filament voltage should be adjusted to the proper sound volume. After that the rheostat has to be returned to the point before a significant volume drop will occur. The colour of the tube top should be a dim yellow. Avoid a bright or even nearly white shine.
Values of capacity are not specified since these are dependent mostly on the frequency characteristic required in each individual case. For low frequency limit f1
  Ca = 1.6 / (f1 x Rg1'),
  Ck = 1.6 / (f1 x Rk).
Some text books show a more complicated method for calculating these by-pass condensers, but this method is quite rapid and gives conservative values. The loss due to incomplete by-passing will be less than 1% for the coupling condenser Ca and about 3% for the cathode by-pass Ck. The condenser size may be halved where economy is essential unless stages are cascaded and highest quality is required.
There is an ignition delay of about 400ms at Ub < 180V. If necessary (e.g. at pulsed operation) the delay time will be decreased by maintaining a glow discharge between auxiliary electrode p and anode a. For that purpose the auxiliary electrode is operated by resistor Rp from a voltage Up negative with reference to the anode.
The bulb is provided with a red contrast filter.
Without filter coating. The use of a blue absorbing e.g. circular polarized amber filter is recommended.
The ignition voltage Ub may be much higher at total darkness.
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 0.8 of the mid-frequency value. For any other value of f1, multiply the of value cathode and bypass blocking capacitors by 100/f1.
The peak output voltage Uout~ is obtained across the grid resistor of the following stage (Rg1') at any frequency within the flat region of the output vs frequency curve, and is for the condition where the signal level is adequate to swing the grid of the resistance-coupled amplifier tube to the point where its grid starts to draw current.
Operating conditions for maximum voltage output.
Operating conditions for maximum voltage gain.
Heater voltage range of 5.2 to 6.6 volts and maximum ratings are established on basis that tube heater will be supplied from batteries in radiosonde and similar applications utilizing equipment designed for extreme compactness and light weight and requiring tube life of only a few hours.
Potentiometer Rk should be adjusted for minimum ripple.
A grid stopper resistor to prevent parasitic oscillations is required, this should be wired close to the valve holder. Automatic bias should always be employed and it is recommended that separate bias should be used for each valve in the case of a push-pull circuit. In cases where the valves are operated well below the maximum voltage or wattage limit, a common bias resistor may be used.
To prevent the "trigger" effect caused by an excessive positive voltage being applied to the grids, a diode, D41, is shunted across the intervalve transformer and bias unit, providing a low impedance to earth for positive voltages. It is essential not to omit this valve.
Self-excited mixer.

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