Checking the emission of radio tubes. Testing of electronic lamps. The idea of lamp emission control

On fig. I shows a diagram of a radio tube tester, with which you can test more than 70 types of transceiver tubes.

Using this tester, you can check the integrity of the filament, the anode current of the lamp in this mode of operation, determine the short circuit between the electrodes and the presence of an open between the electrodes and the base pins.

The power transformer Tpi allows you to get different voltages (1.2; 2; 4; 5; 6.3 and 12 V) to power the filament of the lamps under test. From the same transformer (winding II), a voltage of 60 V is removed; which is used to check the integrity of the filament of lamps. The required heating voltage is set by the P \\ switch.

There are a total of eight lamp panels in the fixture: three with an octal base (for lamps in which the filament is supplied to the legs 2-7, 2-8 and 7-S), two for seven-pin finger lamps (in which the filament is brought to the legs 3-4 and 1-7) and three for nine-pin lamps of the finger series (the glow is brought to the legs 1-6, 1-9, 4-5). Each of the panels on the front side of the device is marked with a corresponding number indicating the numbers of the contact petals to which the filament voltage is applied, and the type 1 of the base.

As can be seen from the circuit diagram of the device, the switching of the lamp electrodes is carried out by toggle switches (toggle switches) Bkj-Vkyu, which allow you to connect any electrode or group of electrodes to a common minus or test voltage, which is removed from the capacitive filter (C,) connected at the output of the rectifier.

For the convenience of using the device, the conclusions from the sliders of the switches Vk, -Vk 9 are connected to the corresponding contact petals of the lamp panels. The numbering of the petals of the panels is the same as in the pinouts of the lamps given in various reference books on vacuum devices. The incandescence of lamps U n is connected directly to the petals of the lamp panels according to the pinout. These petals are not connected to the switches Vk x -Vk but. For lamps in which the output of one of the electrodes is located on the top of the cylinder, a special output B and switch Vk No. This output is included in the circuit with a special plug.

On fig. 2, at the bottom left, as an example, the connection diagrams of the legs of the finger lamp panels are shown, in which the glow is brought to the legs 3-4 (base No. 1), 4-5 (base No. 2) and 1-9 (base No. 3).

When operating the device, in order to reduce possible erroneous switching on, a special table should be drawn up, which indicates the type of lamp under test, the base, the numbers of the outputs of the lamp electrodes to the toggle switches Vk (-Vk 3 and the position of the handle of the universal shunt. The note indicates the numbers of the legs to which the conclusions are made from electrodes of the same type (in the numerator), and the name of these electrodes (in the denominator).A sample of such a table for several types of lamps is shown in Fig. 1.

Before measuring the total anode current, the lamp is checked for the integrity of the filament and the absence of a short circuit between the electrodes.

To check the integrity of the filament, switch I is set to zero, thereby turning off the power to the filament. The lamp to be tested is then plugged into the corresponding lamp panel. If the filament is not broken, the neon lamp L\ will light up. If the filament breaks, the neon lamp will not burn.

To test a lamp (for example, 6Zh1P) for a short circuit between the electrodes, the toggle switches Vk \, Vk g, Vk $ -Vk 7, to which the lamp electrodes are connected (see table), are set to position 1. In this case, all lamp electrodes are connected to each other and join the common minus. The plus of the rectifier through the resistances Rs, Ri, a milliammeter shA with a universal shunt, contacts 3-4 of the Kn button is connected to contacts 2 of the toggle switches Vk \ -V / s 10. If now each of the toggle switches Vk \, Vk $, Vk 6 or Vk g, Vk 7 (simultaneously) is switched to position 2 (and then to its original position), then the needle of the milliammeter shA will deviate only in the event of a short circuit between the electrode under study and some or another electrode in the lamp. By setting the toggle switch (or toggle switches Vk g, Vk 7), at which the milliammeter needle deviated, to position 2 and continuing to turn the rest of the toggle switches to position 2 and back in turn, it is possible to determine by the indication of the milliammeter needle which electrodes there is a short circuit.

The test of lamps for a short circuit is carried out without turning on the filament voltage, i.e., at the zero position of the switch /7 b

When testing the lamp for a break between the electrodes and the output pins, a normal voltage is applied to the filament (in our case, 6.3 V). This is achieved by setting the switch /7] to the appropriate position.

Further, all the electrodes of the lamp are connected to the negative pole of the anode voltage (position I) with toggle switches Vk b Vk g, Vk 5, Vk e, Vk 7. When alternately switching (to position 2 and back) the toggle switches Vk and Vk $, Vk e, to which grid electrodes and the anode of the lamp are connected for this type of lamp (see table), a circuit is formed for measuring the current in the circuit of individual electrodes: plus anode voltage-resistance Rs, Ri-milliammeter TA-contacts 3-4 buttons Kn - contacts 2-3 of one of the toggle switches Vk \, Vk $, Vk v - test electrode of the lamp - cathode - common minus.

In this circuit, the hPa milliammeter will show an increase in current only if there is no open circuit in the circuit of the electrode under test.

When testing the lamp for the anode current, the cathode of the lamp through the contacts 1-3 of the toggle switches Vk 2, Vk 7 remains connected to the common minus, all other electrodes are connected to the plus of the anode voltage by the toggle switches Vk \, Bks, Vk e. The universal shunt is installed in the position indicated in the table. By pressing the Kn button on the instrument scale, the suitability of the lamp is determined by the emission current. The electrical circuit that is formed in this case differs from the previous one in that contacts 1-2 of the Kn button close one of the limiting resistances, and contacts 4-5 of the same button turn on a universal shunt with a maximum measurement limit of 50 ma and a minimum of about 1 ma.

The use of this method for measuring the anode current, which characterizes the emissivity of the cathode, made it possible to implement an easily readable scale of the lamps: the deviation of the milliammeter needle by less than eight divisions of the scale (the entire scale of the device has twenty divisions) indicates the unsuitability of the lamp, more than ten indicates their suitability. The first eight divisions are colored red, the last ten are green. The scale area between eight and ten divisions is colored yellow. If the arrow of the milliammeter is not in this zone, it indicates a reduced emissivity of the cathode of the lamp under test.

The lamp tester is mounted on a duralumin panel and enclosed in a wooden box, covered with leatherette, measuring 150X250X270 mm.

Power transformer 7r, made on a core of Sh-20 plates, set thickness 60 mm. Winding I contains 550 + 85 + 465 turns of PE 0.35 wire, winding II - 275 turns of PE 0.12 wire, winding III - 60 turns with taps from the 6th, 10th, 20th, 25th and 38th turns, and up to the 35th turn, the winding is carried out with a PE 1.2 wire, and then with a PE 0.8 wire.

To work with the device, as mentioned above, it is necessary to compile a table indicating the position of the universal shunt, which is determined when testing obviously good lamps. When calibrating the device, the correct position of the handle of the universal shunt is determined by the indication of the arrow of the milliammeter, which should deviate by 12-15 ° of the scale. Switching the toggle switches to which the electrodes of the same name are connected must be done simultaneously, setting them, depending on the type of measurement, to position 1 or 2. Failure to comply with this rule may lead to an erroneous conclusion about the presence of a short circuit in the lamp or its serviceability.

When testing combination lamps, each part of the lamp is tested separately.

On fig. I shows a diagram of a radio tube tester, with which you can test more than 70 types of transceiver tubes.

Before measuring the total anode current, the lamp is checked for the integrity of the filament and the absence of a short circuit between the electrodes.

To check the integrity of the filament, switch I is set to zero, thereby turning off the power to the filament. The lamp to be tested is then plugged into the corresponding lamp panel. If the filament does not have a break, the neon lamp L will light up. If the filament breaks, the neon lamp will not light -

To test a lamp (for example, 6Zh1P) for a short circuit between the electrodes, the toggle switches Vk, Vk g, Vk$-Vk 7, to which the lamp electrodes are connected (see table), are set to position 1. In this case, all lamp electrodes are connected to each other and connected to the general disadvantage. The plus of the rectifier through the resistances Rs, Ri, milliammeter shA with a universal shunt, contacts 3-4 of the Kn button is connected to contacts 2 of the Vk-V / s toggle switches 10. If now each of the toggle switches Vk, Vk$, Vk 6 or Vk g, Vk 7 (simultaneously) is switched to position 2 (and then to the initial position), then the arrow of the milliammeter shA will deviate only in the event of a short circuit between the electrode under study and any another electrode in the lamp. By setting the toggle switch (or toggle switches Vk g, Vk 7), at which the milliammeter needle deviated, to position 2 and continuing to turn the rest of the toggle switches to position 2 and back in turn, it is possible to determine by the indication of the milliammeter needle which electrodes there is a short circuit.

The test of lamps for a short circuit is carried out without turning on the filament voltage, i.e., at the zero position of the switch /7 b

Further, all the electrodes of the lamp are connected to the negative pole of the anode voltage (position I) with toggle switches Vk b Vk g, Vk 5, Vk e, Vk 7. When alternately switching (to position 2 and back) the toggle switches Vk and Vk $, Vk e, to which grid electrodes and the anode of the lamp are connected for this type of lamp (see table), a circuit is formed for measuring the current in the circuit of individual electrodes: plus anode voltage-resistance Rs, Ri-milliammeter TA-contacts 3-4 buttons Kn - contacts 2-3 of one of the toggle switches Vk, Vk $, Vk v - test electrode of the lamp - cathode - common minus.

In this circuit, the hPa milliammeter will show an increase in current only if there is no open circuit in the circuit of the electrode under test.

When testing the lamp for the anode current, the cathode of the lamp through the contacts 1-3 of the toggle switches Vk 2, Vk 7 remains connected to the common minus, all other electrodes are connected to the plus of the anode voltage by the toggle switches Vk, Bks, Vk e. The universal shunt is installed in the position indicated in the table. By pressing the Kn button on the instrument scale, the suitability of the lamp is determined by the emission current. The electrical circuit that is formed in this case differs from the previous one in that contacts 1-2 of the Kn button close one of the limiting resistances, and contacts 4-5 of the same button turn on a universal shunt with a maximum measurement limit of 50 ma and a minimum of about 1 ma.

The lamp tester is mounted on a duralumin panel and enclosed in a wooden box, covered with leatherette, measuring 150X250X270 mm.

When testing combination lamps, each part of the lamp is tested separately.

On occasion, I acquired a lamp tester L1-3. Since I did not find an intelligible description of working with the device in Russian on the network (there is a more or less intelligible description in English), I am writing to myself as a note. Maybe someone will come in handy.

Description of the device and instructions for use is on the network - be sure to read it. True, after reading, a sufficient number of questions still remain - how to interpret the scale of the device, how to work with maps, what information they contain, etc.

So, a lamp tester of type L1-3 (L3-3 is almost identical in functionality and principle of operation, but assembled on a more modern element base - and therefore more stable and recommended for purchase) allows you to test radio tubes for short circuit, measure the anode current, the steepness in the specified mode, etc.

So, to carry out the test, we need the device itself (L1-3), the test lamp and the card for this lamp. The device comes with a set of cards for testing domestic lamps, however, we are more interested in foreign lamps of the ECC81, ECC82, ECC83, EL84, etc. series. The device allows you to measure almost any lamp, not only domestic ones. For lamps with magnoval base, Rimlock8, Au8 etc. there are wiring diagrams. But in order to test 12AX7, 12AU7, EZ81 we only need a card. A set of maps for foreign lamps is available online. I'll duplicate it just in case. Maps are opened in the SPLAN program (there is a free viewer on the network). For double triodes there are three maps in the file - for the first triode, for the second triode and a common map for two triodes. During the test, with a card intended for two triodes, we fill the holes for only one triode! It is more convenient to use such a card - they inserted a lamp, warmed it up. We measured the first triode. We turned off the device - rearranged the contacts of the pinout of the grid and the anode, turned it on and measured the second triode. It is not necessary to change the map completely.

We print the card, we punch holes (a stationery punch can be bought at any stationery store, we print on thick paper - for example, for watercolor painting). The map above describes the lamp mode (the mode is the parameters - anode voltage, grid bias, filament voltage).

Below on the map are the parameters (according to the datasheet) that the lamp must correspond to when measuring in this mode. Top - mode data.

If you put a map on a universal map (with a description of all holes), you can understand which hole is responsible for what.

Dealt with the cards. The card was inserted, the switching pins were inserted into the card, the test lamp was inserted. The device was pre-calibrated (see the instructions for the device). All variable resistors

1. HEAT (two variables: rough, smooth),

3. Ua (anode voltage)

We put it in the minimum position - counterclockwise.

INSULATION galette - in position PAIR. (parameters).

When we do not press any buttons (buttons - MEASUREMENT and NETWORK (by the way, it is forbidden to press them at the same time)) - the filament voltage is displayed on the scale.

Set the mains voltage. To do this, there is a variable resistor - NETWORK. We press the NETWORK button and set the network to the red risk on the scale - 120 with a variable.

Release the NETWORK button.

Now we set the heat. We set the glow for the ECC81 to 4 and 5 pins of the socket at 12.6 volts.

Now let's move on to the main thing - how to interpret the scale of the device.

The map has a description of the mode: the glow is 12.6 volts, the scale is 15. This means that we must calculate what reading on the scale will correspond to 12.6 volts. There is a formula for this:

Real value \u003d scale reading * coefficient from the card / 150

In our case:

12.6 volts \u003d 126 (on the scale) * 15 (the coefficient indicated on the card for glow) / 150 (maximum scale reading)

To calculate what reading on the scale should be set there is a formula arising from the previous one:

Scale reading = Actual value * 150 / coefficient indicated on the map

That is, for a 12.6 volt glow, this is:

12.6 * 150 / 15 = 126

Everything is simple with the glow - the scale will always be 15, and if we need to set the glow to 6.3 volts, for example, for EL84 we set it to 63. We set it ROUGHLY, SMOOTHLY with the help of the knobs. In the photo, my glow ran a little - almost 12.8v.

The glow directly depends on the NETWORK reading, so we control the network - press the NETWORK key and set it to 120 at the red risk.

Now set the voltage at the anode. According to the map, we should have 250 volts. Scale - 300. We count.

250 * 150 / 300 = 125

We set the PARAMETERS switch to position Ua, press the MEASUREMENT button and set the variable resistor Ua to 125 on the instrument scale.

Now set a negative offset on the grid. We look at the map - it is necessary to set -2 volts. Scale readings - 7.5. We believe:

2 * 7.5 / 150 = 40

We need to set 40 on the scale of the device. We set the PARAMETERS galette to position Uc1 (voltage of the first grid), and since our voltage on the grid lies in the range from 0 to -10, we turn the -10 regulator clockwise. Set to 40 scale.

Everything. Mode set. You can measure the lamp. Check the lamp for short circuits. Set the PARAMETERS switch to the Insulation position. We click the INSULATION - CaC1 biscuit - press the MEASUREMENT button. The device should show zero. We switch to position KS1 (cathode grid) - press MEASUREMENT - we should get zero, etc.

After that - the most important thing - we measure the anode current of the lamp. We return the INSULATION switch to the PAR position. (parameters), biscuit PARAMETERS - set to position - Ia (anode current). Press the MEASUREMENT button. The lamp mode must be set according to the map as we described above - the incandescence, anode voltage and grid bias voltage are set. We get the result on the scale: 108

Let's calculate how much it is in microamps. Remember the formula: real value = readings on the device * coefficient / 150

The coefficient is indicated in the bottom line on the map, where the anode current of the lamp is indicated according to the datasheet. We have 15 for ECC81. We count.

108 * 15 / 150 = 10.8mA

For the popular 12AX7/ECC83 bulb, for example, the scale factor will be different - 1.5. Suppose that we set the mode for it, and got it by measuring the anode current on the scale - 120. We count.

120 * 1.5 / 150 = 1.2mA

Received evidence from the datasheet. It is clear that in reality the anode current of different halves of the double triode will differ and will not correspond to the passport data. However, in order to build a microphone or guitar preamp, the selection of tubes is often not required, more often the assessment is carried out by ear. But sometimes current selection can help if we want more gain or if the circuit has other conditions for selecting tubes (same channel gain, etc.).

(17 Voices)

The article is devoted to the practical measurement of the static anode-grid characteristics of radio tubes in kitchen conditions close to combat ones.
It's no secret that in lamp designs it is useful to know what parameters the lamps have, especially if they have been used for some time. I set myself the task of achieving results strictly on a budget and using available improvised materials and tools.

Measuring stand with lamp sockets and sockets,
including 3 power supplies and measuring instruments plus cords with plugs

Idea

The idea of having a decent lamp tester appeared to me relatively long ago, but I moved in this direction slowly and sadly, stumbling along the way about my own laziness. Additionally, I was slowed down by obstacles in the form of an analysis of schemes that fell under a hot hand, often contradictory, placed on the vast expanses of the Internet and in books.

The last straw that overflowed my patience was eBay, which demonstrated simply space prices for such devices. So, I liked, but used Hickok TV-2C / U TV-2 TV2 Mutual Conductance Tube Tester today costs about 850 US rubles plus 250 for shipping. And to it you still need to add a network trance for 110 volts, watts of commercials for 200, if not more.

Side by side, in the same eBay "e, I joyfully noticed our own, 21-kilogram and very convincing Kalibr L3-3 Russian, a new one that will be sent directly from Ukraine, but its price tag was a significant 850 plus shipping 280, a total of 1130 of the same green, american.

When analyzing the circuit solutions of factory and amateur designs, I often did not have much confidence in the objectivity of the readings of their beautiful color “display meters” with the result “good” or “bad”.

I just wanted to measure the anode currents, which allow to objectively evaluate the emission of lamps, within the limits of the error of my measuring instruments.

What is inside?

Upon closer examination, I found that the coveted unit is nothing more than a number of lamp panels for measured lamps, 3 adjustable power supplies, voltmeters-milliammeters to control current-voltage and intricate switching of all of the above.

The incandescent and grid power sources did not raise any questions, especially since I already had ready-made factory designs on the farm, but the anode voltage source at + 250V caused some concern. With him, I began to move towards the cherished goal.

At the beginning, using the method of successive approximation, the dividing trance for electric shavers, 220/220V, 15W, embedded under plaster, for the bathroom moved into battle. Without hesitation, I soldered a diode bridge with electrolyte to its secondary, borrowed from some former monitor. Then I plugged it in.

And what have we done with the goose? Of course, +310V: no: And I need 250.
Somehow I didn’t want to unwind the secondary, and the next step I took out of the bins was an old, but quite working thyristor power regulator. I twisted the handle down and - voila, there is +250 anode.

Attempt number one, with a whistle and a technical break

For starters, of course, it’s not bad, and the solution is generally workable, but for EL 34 I need good 100 anode milliamps (not counting 15 mA for the second grid), but they turned out somehow with difficulty, I’m already silent about the interference from the thyristor on standing nearby on a shelf, and accidentally turned on the radio.

But when testing the circuit, a new jamb came out: as soon as the 34 warmed up, it suddenly became excited, and the peacefully singing receiver suddenly whistled and wheezed like a nightingale-robber with a cold. The anode current doubled, and the voltage specifically sank under such a load.

Since I have to change my lamp temporarily “to the point”, I, by a strong-willed decision, shorted the 1st grid through the capacitor to the ground. Excited at me, probably offended, but then disappeared.

Of course, it would be possible to make a high-voltage anode power supply using bipolar or field-effect transistors, but it is also prone to self-excitation, it burns with a moment if shorted, and I didn’t have 250-volt zener diodes in my bins.

After some thought, I decided to use LATR to install the anode, but the trouble is that I still haven’t bought it.

I didn’t like the price of 170 evergreens, and the sizes are somehow too large. Plus galvanic connection to the network. Here I again had a long-term technical break ...

In the end, things turned out differently, and much better. Once I successfully bought an ancient transformer with a bunch of taps on the secondary. He honestly once fed the TV, and now, albeit with a native switch, he remained not only homeless, but also completely without a case. And here he is, in person.

Attempt number two, winning

It was in this way (or similarity) that the classic anode transformer design matured for me - simple and indestructible.

And here is the grand total: a test bench with lamp sockets and sockets, including 3 power supplies and meters plus cords with plugs.

To measure possible interelectrode short circuits, I additionally piled a probe on a neon light bulb (Figure 1).

They are supposed to alternately test all the terminals of the lamp relative to the cathode, to which we connect the ground. Then we test against the grid and so on until all the electrodes run out: wink:
This test is done on a cold, then on a heated lamp. Although the same results can be achieved by measuring the interelectrode resistance with a conventional ohmmeter.

During the tests, it seemed to me expedient to apply the anode voltage last, and turn it off first, although the simultaneous supply of all voltages was tested by me and did not cause any complaints.

I do not pretend to be particularly original in solving the problem, but measuring the anode current, and thus determining the spread and residual life of the lamps that I will use in the amplifier, turned out to be quite sufficient for my needs. With minimal changes, this tester can measure a wide variety of lamps.

Figure 2 shows a block diagram of measuring the anode current as a function of the triode grid voltage with an additional lamp vacuum control function.

In the case of a tetrode / pentode, the circuit is supplemented by a 2nd grid circuit (Figure 3).

I apologize for the lack of a heating circuit - sPlan 7 does not give me heating in pentodes: ireful:

In addition to checking the health, the tester allows you to take the anode-grid characteristic of the lamps. To do this, it is necessary to apply a series of voltages to the first grid, obtain the corresponding anode currents, and build a graph by points. Here it is desirable to do without excessive fanaticism and take into account the maximum allowable power dissipation of the anode (and the second grid for tetrodes-pentodes). Landmark - a graph from the reference book - we are equal to it. And you can, for example, measure 3-4 anode currents in the operating range of a particular circuit and select pairs - quartets with similar parameters.

Practical implementation of the lamp tester

The practical implementation of the tester is very close to the block diagram, with the only difference being that the batteries for the glow and the 1st grid are replaced by stabilized laboratory power supplies (Figure 4).

The lamp panels are soldered into sockets, and power supplies and measuring devices are connected to them with connecting cords.

As measuring instruments, I used the multimeters that I have, and the digital voltmeter and ammeter built into the laboratory power supply control the glow.

The anode and the 2nd grid are powered by a transformer with a switched secondary winding, a bridge and 2 electrolytes. Rough setting of the anode voltage is carried out by switching its secondary winding, and potentiometer R5 is used for fine setting.

C2 in the circuit of the first grid eliminates possible excitations of the lamp, opening the SW1 button controls the vacuum - the grid circuit becomes high-resistance and if the vacuum in the lamp is poor, the anode current will increase noticeably. The SW2 button is used to control the absence of an intra-lamp circuit of the cathode and the heater - normally, when it is pressed, the anode current should abruptly reset to zero.

The idea of lamp emission control

The idea of lamp emission control is straightforward: the reference sheet for each lamp indicates the anode current at given anode and grid voltages. I set these voltages (including filament), wait for the lamp to warm up and control the anode current. According to the reference book, the anode current is 100% of the lamp emission. If the measurement showed a lower current, the lamp is worn, and at values less than 40-50%, the lamp must be replaced.

I consider it a pleasant feature of the tester to limit the inrush current through the filament when turned on due to the use of a laboratory current-limiting power supply.

Setting up and using

The tester did not require any special adjustment, but I strongly recommend that you be careful with the anode voltage, the visualization of which is solved on the HL2 neon. Good isolation of the handle of the resistor R5 is also necessary.

Considering that so far I have only been interested in ECC81 and EL 34 lamps, I present their data taken from.

The tester gives an additional opportunity to judge the wear of the lamps by the drop in the anode current with a decrease in the heating voltage. For a good lamp, a 10% reduction in filament voltage should cause a smaller (in percent) reduction in anode current, all other things being equal.

At the same time, it is known that a 5% or even 10% reduction in the filament voltage can significantly extend the life of the lamps.
Later, when the emission of the lamp weakens, it will be possible to return the incandescence to the original one. True, manufacturers do not recommend combining the anode current limit and the minimum filament voltage. Well, I didn't recommend that.

And what will the respected community say about this: will we reduce the filament voltage or will we not?

Literature:

L.A. Dudnik "Testing of electronic lamps"
I.G. Bergelson, N.K. Daderko, N.V. Password, V.M. Petukhov "Receiving-amplifying lamps of increased reliability"
E.L. Chefey "Theory of vacuum tubes"
A.L. Bulychev, V.I. Galkin, V.A. Prokhorenko "Handbook of vacuum devices"

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Amateur radio measurements

Simple lamp tester

The device allows you to determine the emission of the cathode, the short circuit between the electrodes and the breakage of the leads from the electrodes of the lamps and the screen.

The emissivity of the lamp cathode can be judged from the readings of a microammeter connected between the cathode and the first grid. The electrons emitted from the heated cathode charge the electrodes of the lamp, including the control grid, negatively. The microammeter works like a millivoltmeter and measures the potential of the first grid, which varies widely from 10 to 500 mV and depends on the types of lamps and the quality of their cathodes.

The readings of the device are compared with the emission of known good (calibration) lamps. Such calibration is carried out during the adjustment of the device, while it is necessary to use as many types of lamps as possible. The data is entered into a table.
When checking diodes and kenotrons, a microammeter is connected between the cathode and anode.

Toggle switches Vk1-Vk6 connect all other lamp electrodes to the device. In the absence of interelectrode short circuits and breaks in the leads, the readings of the device should increase at the same time. So, for example, when checking a lamp, the device "AVO-5m" (limits 60 and 300 μA) showed a current in the circuit of the first grid of 50 μA, when the second grid was connected - 70 μA and when the anode was connected - 90 μA.

When checking the kenotron, the device "School AVO-63" in the circuit of the first anode showed a current of 4.9 mA, when the second anode was connected - 10 mA. In both cases, the lamps were taken from operating equipment.

Switch P1 (with a neutral position) switches the measurement limits of the device, the values of the resistances R1 and R2 are selected when adjusting the device according to the best radio tubes.

For the manufacture of the device, a step-down transformer with a power of 10 ... 20 W, a microammeter for 50 ... 300 μA and eight toggle switches are required.
The windings of the Tr1 transformer are wound on a core made of ShL-16 plates, the thickness of the set is 25 mm. The primary winding contains 1100 turns of PEL 0.35 wire plus 800 turns of PEL 0.27 wire. Secondary winding at 4.5; 6.3; 12.6; 20 and 30 V - respectively 48 + 12 + 18 + 78 + 84 + 120 turns of PEL 1.2 wire.

You can use a transformer assembled on a core of Sh-20 plates with a set thickness of 20 mm with a primary winding of 1360 turns of PEL wire 0.34 + 1000 turns of PEL wire 0.27 and a secondary winding of 43 + 11 + 13 + 63 + 74 + 100 turns of wire PEL 1.0.

The device can check the emission of kinescopes and oscilloscope tubes.

Eng. V.Leonov. "Radio" No. 12/1965

Comments on the article:

Checking the emission of radio tubes. Testing of electronic lamps. The idea of ​​lamp emission control