SU62625A1 - Device for removing characteristics of electronic tubes - Google Patents

Description

When developing and researching vacuum tubes, it is necessary to have their characteristics expressing the dependence of the anode current on. grid voltage and anode current from the anode voltage. The presence of a family of characteristics makes it possible to judge the decay of the anode current curves with increasing grid voltage and to correctly choose the operating mode of the lamp.

To take the characteristics of electron tubes, devices using an electron beam oscilloscope were proposed, in which periodic pulses of voltage of a sawtooth shape were applied to the grid of the lamp under study and to the deflecting plates of the oscilloscope.

The proposed device, the schematic diagram of which is shown in the drawing, is intended to compensate for the influence of the load from the grid circuit of the vTaMnbi under study on the shape of the pulse curve of the relaxation generator.

The test lamp 1 is connected through a small resistance 3 to the source 2 of direct current. The voltage drop across the resistance 3 that occurs when the anode current passes, can be applied (directly or through the appropriate amplifier using switch 25) to the deflection plates of the electron-beam oscilloscope 4. A bias voltage is applied to the grid circuit of the lamp under study / Uc from a DC source 5. In addition, a pulse voltage from a relaxation generator, consisting of a thyratron 8, can be supplied through the thyratron 7 to the grid circuit of this lamp between the anode and the cathode. 9, a capacitor, being charged from the source 10 through the d.c. valve tube 11 with adjustable incandescence. A feature of this relaxation generator is that parallel to Kenotron 1J a lamp 12 is turned on, the anode current of which increases smoothly with an increase in the grid voltage due to a drop in voltage on the resistance 13 connected between the said relaxation generator and an additional relaxation generator. Analog No. 62625- 2 -

but the previous one, an additional relaxation generator consists of a thyratron 14, a capacitor 15, a kenotrope 16 and a source 17 of direct current.

The relaxation generators are arranged so that, in the absence of a load in the grid circuit of the lamp under study (resistance 13 is taken sufficiently large), both generators give identical in form and phase voltage to the sawtooth. Obviously, at this m. The current flowing through the resistance 13 will be zero, and the current flowing through the lamp 12 will be negligible.

In the case of a load of the first relaxation generator on the grid circuit of the lamp / shape of the sawtooth pulses created by it, it is obvious that it will decay (decrease), due to which current will flow through resistance 13, which creates voltage on it, plus directed to the grid of lamp 12. This lamp will flow anode current, increasing with an increase in its grid voltage, as a result of which the capacitor 9 will be charged faster. This will lead to an increase in the voltage on the capacitor and, consequently, to the compensation of the EFFECT of the load from the grid of the lamp under study /. The voltage on the grid of the lamp 12 from the resistance 13 for amplification of the effect can be supplied through an amplifier.

This compensation of non-linearity of the voltage resulting from the non-linearity of the characteristic of the grid current of the lamp under study is of great importance, since in the absence of compensation a distorted characteristic should be obtained.

As already indicated above, the sawtooth voltage from the first relaxation generator is fed through the thyratron 7 to the grid circuit of the probe under test /. Thyratron 7 is intended to periodically (at desired intervals) open the lamp grid circuit. Moreover, the use of a thyratron for this purpose is explained by the fact that during the passage of current through it the fall of the voltage on the neat (according to the known property of the gas discharge) is almost independent of the strength of this current. This circumstance is of great importance from the point of view of the distortion of the grid voltage curve due to the nonlinearity of the characteristic of the grid current. If instead of a thyratron 7 it was stoolistic resistance, then when a grid current passed through it, there would be a voltage drop corresponding to the shape of the grid current curve, which would distort.

Periodic "locking and" unlocking of the thyratron 7 is carried out using a push-pull relaxation generator having 18 19 thyratrons, the anode circuits of which are powered from the direct current source 20. The filament circuits of these thyratrons are connected through series-connected resistances 21 and 22, in parallel with which capacitor 23 is connected. The purpose of the latter is to alternately periodically squeeze the gas discharge in the thyratrons 18 and 19.

On the resistance 24, a positive pulse periodically arises, which regularly unlocks the thyratron 7. The duration of this pulse can be adjusted with the help of sliders on the resistances 21 and 22.

The grid voltage of the lamp under study / is supplied to the deflection plates of the pasiBepTKH electron beam oscilloscope, the voltage drop across resistance 3, proportional to the anode current, is applied to the deflection plates via a two-pole switch 25. This voltage drop can be directly applied to the amplifier through the amplifier . The latter should be done when

It is undesirable to introduce a large resistance distorting the characteristics of the anode current into the anode circuit.

Since the grid voltage of the lamp 1 varies linearly with time, the curve of the anode current in time obtained on the screen simultaneously (on an appropriate scale) will also be the curve of the anode current depending on the grid voltage.

In the same way, the characteristic of the dependence of the grid current on the grid voltage can be obtained. For this, the switch 25 was set to the right position, as a result of which a voltage drop across the resistance 26 proportional to the grid current would be applied to () 1 ;;.;

Synchronization of relaxation generators, working on them with cS and 14 thyratrons, can be achieved by changing the heating of the kenotrons // and 16 and, moreover, by connecting the anode circuit of one thyratron with the grid of the other (this connection is not shown in the drawing) .

The power sources 10 and 17 of the anode circuits of thyratron 8 and 14 can be combined. The power sources of the grid potentiometers of these thyratrons can also be combined.

It is obvious that the oscillation frequencies and the duration of a positive impulse on the resistance of a 24-stroke relaxation generator operating on thyratrons 18 and 19 should be appropriately chosen.

With the help of some addition, for example, described in ed. St. No. 45338, on the screen of an electron-beam oscilloscope, the characteristics of the anodic and grid currents can be obtained simultaneously, which presents some convenience in terms of a joint analysis of these characteristics.

Subject invention

A device for capturing the characteristics of electron lamc using a cathode ray oscilloscope by applying periodic pulses of a sawtooth voltage to the grid of the test lamp and to the deflection plates of the oscilloscope, in order to compensate for the effect of the load from the grid of the lamp under study on the shape of the curve pulses of a relaxation generator, the device uses a second relaxation generator, identical to the first one and connected in parallel with it through resistance, and parallel to the kenotron A generator regulating the charge current of the capacitor included an additional lamp, the grid circuit of which is connected to the aforementioned resistance so that if the pulse generator of the first generator distorts and a current occurs in the circuit containing the resistance, the voltage drop across this resistance caused an increase in current through the lamp and, therefore, voltage rise on the capacitor.

- 3 - № 62625

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