Anode throttle. Anode throttle How to make an aode throttle for kV amplifier

Well, I love radiolmpa ...
Sergey Komarov (UA3ALW)

When working output cascades of transmitters with a parallel circuit inclusion circuit and power supply in the anode chain, it often happens that the anodic chokes are warm and burning. The designs of the anode chokes are published dozens, but in no one article there are clear recommendations for the design of throtters for transmitters with the AEM range of 200 m. Since broadcasting transmitters work continuously by many hours, without turning off, the design of a reliable anode choke is the actual task.

Part 1. Kostruitive design aspects. The formula of the optimal choke.

Anode throttle in the parallel power scheme of the transmitter output cascade (Fig. 1) serves to supply the supply voltage to the lamp anode and at the same time, it should not pass through itself a variable of the anode current, backward, to the source of the EA, which must enter the output oscillating system . However, nothing perfectly happens, and the anode throttle cannot have zero resistance on constant current and infinitely large on the variable operating frequency. And alternating current into the throttle is flowing.

Many contradictory requirements are presented to the anode throttle, which we will analyze in this article and, if possible, satisfy. Do not forget about the capacitors of the Sat and CP, the modes and the denominations of which depend on both the parameters of the anode chain and the choice of the throttle.

From the point of view of obtaining maximum quality fault (minimization of RF losses) choke should be single-layer and large diameter. Even a ratio for obtaining maximum inductance with a minimum length of the wire is known: the winding length is 2.5 times less than its diameter. That is, he must be a thick and very short coil.

From the point of view of reducing losses for vortex currents, a single-layer choke must be wound with a wire not thicker 0.6 mm (optimally - 0.3 ... 0,6). With diameter less than 0.3 mm, the active resistance increases smoothly, and heat losses increase, and with diameter more than 0.6 mm, the losses for vortex currents increase quite sharply. With a multi-layer winding, the optimal diameter of the wire lies in the range of 0.2 ... 0.35 mm. With thicker wires, the loss of vortex currents increase so much that the overall resistance of the coil increases sharply and the goodness falls quickly. When using a lytzentera, the wire cross section compared to one-core can be increased, since the alkali is thin and losses for vortex currents are not significant. In the limit, for multilayer chokes of powerful RED transmitters of the range (153 ... 283 kHz), we can recommend a litezpectant with a diameter of residents to 0.25 mm.

From the point of view of reducing the RF losses due to the surface effect (at frequencies up to 3 MHz), the choke must be wound with a literature with a diameter of one vein no more than 0.1 mm.

From the point of view of minimizing the turning out of current from the cross section of the wire due to magnetic fieldcreated by neighboring turns, the choke should be wind into a step of at least two diameters of the wire, and with a multi-layer winding, make the distance between layers equal to the wire diameter. However, when crossing the turns in neighboring layers, this effect is significantly weakened and the winding "Universal" will help us.

When there are many turns placed in many layers in the throttle, its interstility and interlayer tank grows, the choke ceases to work as inductance and begins to carry out capacitive currents, which leads to a decrease in its equivalent resistance and an increase in the branch of the anode current variable in it. Thus, to perform its filtering functions, the choke must operate at frequencies below its own resonance.

The throttle frame must be very rigid and at the same time as the minimum amount of foreign material in the magnetic field (tube with thin walls or individual edges).

With a voltage drop and power loss on the winding resistance, as a result, with the diameter of the winding wire, the engineers have figured out long ago, even when the first transformers were designed in the year before last. From the radio amateur directories of the 50s of the last century, the formula for selecting the optimal value of the diameter of the copper winding wire d (mm) \u003d 0.02 √I (MA)Thinking the current density in the wire 3.18 A / mm 2 , and almost all produced transformers for ground equipment (including Tan, TN, TA, and CPA) are counted on it. But since in transformers, the heat sink from the wire is difficult (the coils are located inside the thick winding, isolated layers and outside electrical and heatinsulating materials), and in the throtsels of the turns are open, the windings are thin and convection heat sink from them are much better, then the current density can be allowed in the winding to 4 A / mm 2 , and sometimes up to 4.5. Therefore, 10% overload throttle in the current (relative to the calculated value of 4 A / mm 2 ) Permissible.

Large inductance with minimal wire length can be obtained using a multi-layer winding. The greater the cookers are located, with the same length of the wire, the inductance will be more due to the mutual induction. To reduce interspervic capacities, use a multisective winding of the "Universal" type.

The diameter of the choke carcass take several times less (in 3 ... 4) than the diameter of the coil of the oscillating circuit, since the inductance and active resistance diameter depend on the linearly, the resistance depends linearly on the number of turns - quadratically. Based on this, to achieve the desired inductance, we will cross multiple turns on a relatively small diameter. In addition, the negative impact of the interspervic capacitance at a small length of the coil will affect the higher frequency. But with a small diameter, the winding the coil turns out a small quality rate (Q \u003d Xdr /r sweat)- RF losses grow in choke. However, all conflicting requirements can be satisfied.

The final formula of the optimal average-raster HF choke: many turns on a relatively small diameter: narrow sections with winding "Universal", at a small distance from each other and with a large number of sections! The hot end of the throttle is at the beginning of the winding. An increase in the diameter of the frame gives an increase in Q Q Q (loss), so for different levels Transmitter power will result in different diameter chokes.

For example, photography of throttle ears4.775.000 with an inductance of 5000 μg of industrial lamp (GU-81M) of the medual-wave marine transmitter "Volkhov-M" 300 W (AM, CW) of the frequency range of 400 - 535 kHz (hot end - left, fasteners - right ) Photo 1:

30 mm throttle frame diameter, 104 mm length, 6 mm sections width, distance between sections 3 mm, number of sections - 7, the total length of winding winding 60 mm, winding thickness 2.5 mm, PALSHKO wire 0.25 mm, the number of turns in One section 89. The diameter of the contour variometer with which the throttle works "paired" - 100 mm. The hardness of the choke 55 at a frequency of 460 kHz. Capacity of the blocking capacitor from the cold end of the throttle of 3900 PF (CSR-13).

Now about the variable component of the current through the throttle. It is it that determines the throttle reactive power.

And in our case it will also be optimal decision. However, no one prohibits the freedom of creativity and if you still want to apply a parallel scheme in transmitters with a capacity of 2 ... 5 W, then two outputs are possible. The first is the most preferred, it is still, abandoning the throttle (insist) and move to the serial power scheme of the anode circuit of the output stage, while putting the variable and the constant components of the anode current through the contour coil. The second is since the power of the transmitter and the anode current is small, choose the inductance of the throttle at which Xcalmost complaims S. RA. - at low power and power from the power grid, the transmitter efficiency is not very important and with active losses in the throttle can be put up. - Even with the questionality of the throttle Q \u003d 10 (well, there is nowhere below), the transmitter efficiency due to losses in the throttle will decrease only by 7% (loss - half from 1 / q, since 0.707 variable of the anode current flows through the throttle). Well, and, 150 MW (5% of 3 W) do not overheat the choke.

From the point of view of energy loss in the choke itself and its heating, the variable component of the throttle current ID 1. It has a determining value. Taking into account the relatively large relationship between the inductive and active resistances of the choke coil at the operating frequency, the module of its impedance will be approximately equal to inductive resistance, and ID 1. It is defined as the ratio of the variable component of the anode voltage to the inductive resistance of the choke: Id 1 \u003d.UA / xdr.

Losses in throttle on alternating current P D1 \u003d.I 2 d 1 xdr /Q. = (EA -EA MIN) 2 / (kRAQ).

Putting, for example, the transmitter power of 5 W and Xdr \u003d 1,3RA, with Ea \u003d 250 V; EA. MIN. \u003d 60V (Lamp 6P1P or 6P6C); With the question of choke 30, the losses in it will be:

P D1 \u003d.U 2.a / (kRAQ) = 190 2 / (1.3 x 3610 x 30) \u003d 0.256 W; With q \u003d 15, they double, but still halfway the choke does not overload.

Therefore, in transmitters with power in the area of \u200b\u200b5 W, we do this: Xdr \u003d 1,3 RA. However, as a preferred option for the transmitter power in the watt unit and less, remember the consecutive scheme of the anode chain (Fig. 2) - I insist for the third time!

With an increase in the power of the transmitter, voltage, currents and losses in the throttle and the required inductance falls. For example, at 25 W Power, reactive power Throtes of 15 W and loss of about 2 W, with Q \u003d 15, will already cause the complexity of its implementation. Therefore, the variable the component of the anode current, which bore in the choke should be less, and its inductive resistance, respectively, more. With the ratio of resistance xdr \u003d 2.5 RA, The throttle reactive power will be 16% of the transmitter output power, which, according to the absolute value of the loss power, resembles the previous case. Losses are small. It is suitable.

With a transmitter capacity of 100 W, the sixth part of the power is already significant and losses may be tangible. Increased the ratio of resistance to XDR \u003d 5 RA, The reactive throttle power will decrease, and the losses will remain the same, 0.5 ... 1 W depending on the questionality of the choke. Meanwhile, the most frequent values \u200b\u200bof the questionality of the throttle 15 ... 30.

With the capacities of 400 - 500 W and above, it is desirable that the active power dissipated on the throttle would not exceed the first watt units, respectively, reactive, would not be more than a hundred. CDR \u003d 7 ratio RAallows you to implement this condition.

If you consider the heating of the throttle during the operation of the transmitter (for example, in broadband connected radio stations, not intended for long-term transmission), it is possible to reduce k. To the value in which the throttle losses will not exceed the norm specified and, as a result, the overheating temperature of the throttle.

In the literature, the ratio for the anodic chokes of transmitters is known: the ratio of the side surface area of \u200b\u200bthe single-layer winding to the scattering power should be approximately 20 cm 2 / W. With a smaller value, the throttle will overheat, with a larger - the frame of too large diameter is not rationally selected. Since the cross section of each section of the throttle with winding "UNIVERSAL" is relatively small, the winding is divided into sections, which are related to each other and there is a convection cooling between them, it is quite acceptable to focus on the given ratio.

The side surface area of \u200b\u200bthe throttle HS4.775.000 is:

S. side \u003d π NC [(D 2 in D. 2 k) / 2 + DB l.c] \u003d 7 π [(3.5 2 - 3 2 ) / 2 + 3.5 x 0,6] \u003d 81.9 cm 2 ;

where, NC is the number of sections; DB - the external diameter of the winding section; DK - the diameter of the frame; l.c - width of the section. Considering that every 20 cm 2 the side surface of the winding can dispel 1 W, permissible scattering power on this choke will be 4 W.

Than powerful transmitter And the longer it works for transmission in normal mode (it is especially true for broadcasting transmitters), the more carefully it is necessary to design a throttle in its anode chain, and choose a larger diameter frame to ensure high quality, or (at frequencies to 2.5 ... 3 MHz) Use for winding a lytzentera.

Inductive impact of the anode choke at the bottom operating frequency of the range must be approximately specified above k. Once larger than equivalent load resistance in the anode chain RAWhen the output Cascade of the transmitter issues the specified power. Accuracy of meaning Xcwithin ± 12 ... 15% is quite admissible when designing a single-frequency transmitter, but when working in the frequency band, it is necessary to be laid in tighter tolerances, since the real chokes, the ratio of the upper and lower operating frequencies is rarely more than 1.5. Therefore, before designing an anode choke, it is necessary to calculate resistance RA. Since the range of transmitter output power is set by technical requirements, and the nomenclature of recommended radiolmps for low-power transmitters is finite, you can make the following table:

Table 1.

P Nes.

Output lamp

Ea Nes

EA Min.

P D. 1 *

2 x 6p6c, 6p1p

2 x 6p43p, 6p18p

2 x 6p37n, 6p41c

2 x 6p37n, 6p44c

Notes: Power in watts, voltage in volts, currents in milliamperes, resistance in ohms, wire diameter in millimeters, inductance in microgenry. Anodic voltages are given taking into account the fact that the lamps work in a pulse mode and voltage Ea Nes present on the anode locked radiolmpa; On the anode open radio voltage is present EA MIN.. Through the fraction given values RA Between the leaps of lamps in the two-stroke scheme. Multiplers 2 x, 4 x show how many radiolmps operate in the output cascade of the transmitter under the control of a multiphase synthesizer.

* Losses in the throttle on HF are calculated: for lines 1 ... 4 at q \u003d 16; for lines 5 and 6 at q \u003d 22; for lines 7 ... 12 at q \u003d 30; For lines 13 ... 16 at q \u003d 40. ** Radiolamp 1P24B is designed for wearable portable transmitters with batteries.

Estimated ratios for the values \u200b\u200bgiven in the table, are valid for the boundary mode of classes INand FROM,as well as for pulse class mode D.and F inv.:

1. AM amplitude voltage on the anode lamp: UA \u003d EAEA Min.;

2. Equivalent resistance: Ra \u003d.U 2.a / 2.P carried;

3. The effective value of the throttle component variable: ID 1 \u003d 0,707UA /kra;

4. The determination of the constant component of the anode current will require several actions:

4.1. The amplitude of the first harmonic current Ia 1 \u003d 2P carried /UA;

4.2. Anodic current pulse amplitude Ia Max \u003d.Ia 1 / α 1;

4.3. The constant component of the anode current: Ia 0 = Ia max α 0;

where α 1 \u003d 0,604 and α 0 \u003d 0,401 - Flat pulse decomposition coefficients at bed q \u003d 5/2 \u003d 2.5 (When using the C9-1449-1800 synthesizer), alternately operation of two radiolmps and, taking into account the real duration of the edges of the current pulses of the anode 20 ... 25 ns). To excite the output cascade of the transmitter from the S9-1449-1800-4 synthesizer, having a diversity of the output pulses 5,333, α 1 \u003d 0,587 and α 0 \u003d 0.377.If you want to make a transmitter for linear gain in class B mode, with the initial lamp current only by installing the operating point to the beginning of the linear section (for SSB or OFDM signals), the cut-off angle will be 90 ° , and the current pulse shape will become cosine, the decomposition coefficients will be different: α 1 \u003d 0.5 and α 0 \u003d 0,319, And the constant component of the current through the throttle will be 4% less than in the first case. And taking into account 4% of the stock value Ia 0 In Table 1, you can not recalculate.

The final formula will take the form: Ia 0 = 2 P carried α 0 / (UA α 1);

5. Full throttle current loading its wire is the root square from the sum of the squares of the variable and the constant components: ID \u003d √ (I 2 d 1 +I 2.a 0);

6. The diameter of the winding wire of the throttle at a current density of 4 A / mm 2 will be: d \u003d 0,018 √ID; Where d. - in mm, and IDD - in Ma.

7. With the fact that the inductive resistance of the choke at the lower operating frequency f N.must be B. k. Once bigger RAThe inductance of the throttle will be: LDD \u003d. k.RA / (2 πf H);

where f H \u003d 1449 kHz- Lower frequency 200 meter broadcasting range of medium waves.

8. The loss power in the throttle is made up of alternating losses and on constant current:

PDR \u003d P D. 1 + P D. 0 \u003d Ua iD. 1 / Q + I 2 A 0 RDD. Alternative currents can also be calculated according to the following formula: P D1 \u003d.U 2.a / (kRAQ)where, RDD is the active resistance of the throttle on constant current, q is the quality of the throttle at the operating frequency (typical values \u200b\u200bare given above).

From Table 1 it follows that with the capacity of up to 100 W optimal choke, inductance in the area of \u200b\u200b400 - 700 μg (lines 1 - 10). From the experience of designing self-made medium-raas broadcast transmitters of a range of 200 meters on lamps 6P3S and 6P7S in the 50-60s of the last century, the "folk" design of the anode throttle, made on the Sun-2 resistor, resistance 1 mΩ or more, and which contained five Winding sections "Universal" 100 turns, PELSHO-0.25 wires (Fig. 3).

The accuracy of the coincidence of the inductance of the "folk" choke with the calculated inductance of the throttle according to the radiolamba regime 6P3S is 635 μg (Table 1, line 6).

Now about the maximum work voltage Throttle for the strength of insulation wire U PR Max. Electric strength (breakdown voltage) PELSHO wire isolation at a frequency of 50 Hz is 700 - 1200 volts. We consider the worst case. The operating voltage must be 2.5 - 3 times less than the proof, that is, there can be no more than 250 volts on adjacent wires. With an increase in frequency, this voltage must be reduced, however, since the main insulation falls on a relatively loose silk winding (mainly air, or polystyrene impregnation, or paraffin, possibly ceresine - the frequency properties of which are good), then it is not necessary to reduce the frequency properties. Suppose that at frequencies up to 2 ... 3 MHz, this decrease will be 1.5 times, that is, on the adjacent wires, the working WF voltage should not exceed 160 volts.

When winding the type "Universal" in the dimensions indicated on the drawing, sizes and 100 turns in the PELSHO-0.25 wire section, the number of double cross-layers will be four (it can be seen on the winding, side). If you take a permissible working voltage between adjacent double layers of 160 volts, then the operating voltage applied to the same section will be 640 volts. Full tension on all five choke sections - 3200 volts. Since with AEM amplitude of the RF voltage on the circuit (and therefore in the choke) can reach almost 4ea Nes, then with a small reserve of EA Nes There should be no more than 800 volts. It seems that this throttle is suitable for its insulation, not only for radiolm views 6P3S and 6P7S, but even for M-807, just for gooding to each section it will be necessary to wind 135 to receive two times greater inductance. An additional 35 turns form another double layer of the winding, and therefore the choke operating voltage can be increased to 4000 volts. Accordingly, the anode power voltage of the transmitter output cascade where this choke can be applied to 1000 volts. It turns out that such a design and for the RadioLamps GU-50 is also suitable (but provided that there will be 135 turns in each section). Here it is, folk creativity, tested by more than half a century history!

In addition to the maximum throttle voltage based on insulation strength (take into account the peak of the modulation), there is still a long-acting amplitude of the alternating operating voltage of the current throttle (take into account the carrier mode), defined as the product of the sinusoid form coefficient √2 on the inductive impedance of the choke at the bottom operating frequency X L. = 2π.f N. L. (wheref. N. \u003d 1449 kHz for 200 m range of medium waves), and to the maximum efficient current value for the wire that throttle is wound I (MA) = (d / 0.02) 2.

U I MAX = 0,707 π F N. L.(d / 0.02) 2

This voltage shows, in a chain with which maximum variable voltage, this choke can be included so that through it does not flow of the RF current more permissible for its wire. When designing transmitters, it is necessary to take into account both maximum voltages U PR Max and U I MAX.

In the 40s-50s of the last century, the R-104, P-105, R-108, R-109 was done in the 40-50s of the last century in the low-power lamp army radio stations. However, this scheme has an extremely low filtration of harmonics, and is applicable only in low-power transmitters and tactical connected radio stations.
Technical requirements for transmitters of individual broadcasting are given in the article "Transfer Complex of Individual Radio Broadcasting", Radio 2015, No. 9, p. 21-26.

Fig. 17.
KPU with a separated stator can be used as an anode capacitor in the P-circuit and provides its optimal setting, provided that there is a sufficient distance between the plates (so as not to pierce the RF voltage. There is another method for reducing the initial capacitance of the anode kp. By connecting this capacitor to the removal From the coil of the P-circuit, we achieve a decrease in the capacitance introduced in the circuit and reduce the effect of the KPE to the frequency of its setting - UA9LAQ).
KPU with air dielectric and vacuum: capacitors with air dielectric easier to find, they are cheaper, but have some drawbacks outlined above. Vacuum kpe - roads, they are not so easy to find, but only they, sometimes provide a P-contour, all that we want to get from it and without the use of additional switchable capacitors of constant container. Another advantage of these capacitors is a high working voltage, insensitivity to pollution of the surrounding atmosphere and changes in its humidity and pressure and can conduct large RF currents. I have never heard that any vacuum capacitor shoots or arc formed in it. The average vacuum type capacitor used in the Amplifier can pass through itself the RF currents in many times larger than those that can give real ra. Most vacuum capacitors change the capacity from the minimum to the maximum turn of the regulatory axis (multi-turn). The design of the vacuum kp allows you to set various sample devices with a reset and installation to a certain position required for individual ranges. The limiters at the beginning and end of the adjustment of the CAP container are also provided to avoid damage. Installation of vacuum kpa may be a problem, or maybe not, since most of these kPs contain and mounting devices, if any, it is not easy to make them. Vacuum kpa can be mounted in any position: vertically, horizontally, in suspended position.
For truly powerful amplifier, the best choice There will be an application of vacuum kpa that does not flash even with very large facilities summed up to them. Yes, they are not cheaply, but the miser pays twice ... (hitting a small part of the air during storage, transportation or operation make such a kpa absolutely unsuitable due to the occurrence of discharges in them. Before use, you need to check the kpe for leakage using a high-voltage tester and protect them From deformation and shocks during operation - UA9LAQ).
One moment: The higher the anode voltage used in the amplifier, the harder it is to find the appropriate KPU with an air dielectric, which would stand the constant anode voltage plus the RF and the cause of arcs or problems with overlapping over a container. At a voltage on the anode of lamps (s) of the RA in 3 kV, it is also possible to allow the use of KP with an air dielectric, the problems of using them with anodic voltage of 4 kV and more increase in the exponential law. (The author, apparently, means directly connecting the KPE to the lamp anode without a separation capacitor, but also included after the separation capacitor, the anode capacitor with an air dielectric in the P-circuit should have an elevated distance between the plates: an output resistance increases with an increase in anode voltage Lamps, and, it means, RF voltage increases, it means that the risk of a gap between the plates of the KPU is increasing - UA9LAQ).
When buying vacuum kpa, pay attention to the state of the electrodes (plates) inside the glass case. If they lost their shining copper look, then it is most likely a vacuum is broken in the kp. If, with the full twisting of the adjusting screw, there is no resistance exerted during the dilution of the plates, then most likely the KPE is broken. In general, the movement of the plates inside the kPa must be accompanied by resistance (effort required), and the insides must glitter, as if they had just expored them. Otherwise, it is better to go through this kp side!
Range switch: Do not missed this important part of RA. Buy yourself the best as you can get. Otherwise, just, regret! Very decent switches manufactures Radio Switch Corp. Their model of model 86 is good, however, the best is the top model switch 88. This switch is designed for a voltage of 13 kV and a current of 30 A. Even 5 kW transmitter will not be able to "light the arc" on this switch. For p- or L- Cuttings in this switch will be required at least two dialing of contacts, but three are better. The contact group must be provided for each range from those used. The special adapter must be used to connect the axis of the switch in the P-circuit with the axis of the input circuits switch ( i.e., when switching Ra ranges with one handle). If there are resistors (adaptable input) at the input, then, naturally, the need for an adapter disappears. There is another possibility of using individual switches at the input and output of the amplifier, but to eliminate the installation Switches to an incorrect inappropriate position, it is necessary to apply any blocking: mechanical or electronic.
In fig. 17 shows a switch configuration that will help the novice designer to understand the requirements for the P-circuit on the ranges of 160 ... 10 meters. Pry away with such switches and fairs, markets, and also look on the Internet, and good used seconds will go.
Piley chokes: The throttle in the circuit of the lamp of the lamp with the cathode of the direct heat is absolutely necessary, during warming cathodes, like the type 8877 lamps, and without such a choke can do. The cathode of direct heat can be found almost in all old powerful lamps With a glass cylinder, as a thread of the glow and cathode, a toolted tungsten is used there. At such a cathode, there are both high currents and a large HF voltage that should be untied from penetration into other chains, so that there are powerful chokes here. Such a throttle is usually cumbersome, its winding is made by double wire, the turn to the turn on the ferrite rod and contains the number of turns sufficient for complete removal HF after throttle. Unleashing capacitors usually put immediately after the throttle from the supply of heat supply voltage from the power supply, on the body. This type of choke is a very large amount of inductance, while it provides passage through itself a lot of currents, I also tried the use of a toroidal throttle and remained satisfied, especially since this choke had small dimensions.
In lamps with heated cathodes, such a cathode is an oxidized "sleeve", dressed on a gas thread, which heats it to obtain an electronic emission. Cathodes of this type require smaller flow currents than the first to be addressed above and do not allow the distribution of HF, since The cathode "sleeve" has a permanent shielding effect (the outer side, according to the skin effect radiates and is drawn into the scheme of functioning of RF currents, the lower RF currents are not exposed and serves as a closed screen, and here you can still remember the currents of Fouco - UA9LAQ. Nevertheless, chokes in the heat circuit are needed to exclude the hit, even if the random emission of the RF into the feed complex. Glow throttle in schemes with lamps having heated cathodes should no longer be greater, bulky, have greater inductance, because the currents acting in the circuit of the RF. The choke has small dimensions, wounds with a double-wire sufficient cross-section for passing the flow current in rubber or teflon isolation, the winding is made on a small ring or rod ferrite core. The inductance of the throttle to work on the ranges of 160 ... 10 meters should be 30 ... 300 μH. The disconnecting capacitors are included with both heat wires on the amplifier housing at the point of connection to the choke from the power supply. Put the capacitors between the heat wires from the base of the lamp and the cathode. The connection of the filament on the HF with the cathode will contribute to the equalization of the HF potentials on both. This will interfere with various kinds of inhomogeneities in the signals: flashes, shrouds, cristers, breakdowns, equalize both edges of the filament on HF, which will eliminate the fluctuations in the slope.

Fig. eighteen
In fig. 18 shows a typical scheme for turning on the lamp with a heated cathode with the usual slight throttle.
Alc:This scheme must be done necessarily. It is possible to do without it in the event that you use a lamp that can solve the full power of the existing pathogen. An example may be a 3CX1200A7 lamp, which can be swollen up to 120 W, inclusive. However, regardless of whether you use the lamp 8877 or 3CX800A7, 120 W power is enough to systematically disable the grid. The ALC system prevents this, but if you "like" the lamps change more often than it is required, do not make any Alc. The best point of reference to the amplifier is the point between the Relax / Transmission of the input and the input configurable device.
The ALC scheme detects in the amplifier a small part of the input RF signal of the pathogen. This straightened signal - negative polarity and may vary in the range from -1 to -12 V. The signal changes in the negative side is given back to the pathogen, which shifts the power amplifier in the pathogel, and in turn reduces the output power of the pathogen and it prevents the termination of the terminal Ra.
The Alc threshold installation procedure is as follows:
1. Configure the amplifier to the full output power.
2. Set up the Alc threshold installation potentiometer Such a level so that in the output signal there is a hardly noticeable reduction in its power.
3. Everything. Installation is completed.
After installing the ALC threshold, the level of Ruffling can be increased or reduced, but the maximum output power of the amplifier installed using the ALC regulator will not be exceeded.
The alcohol arrangement of the ALC system can be both on the back and on the front control panel, but, in any case, is well labeled. The installation adjustment justifies itself in practice, since this cannot be randomly shot (for adjustment you need to take a hole and then climb under the cover, removing a possible retainer). Once installed, the Alc threshold adjustment rarely changes.
In fig. 19 shows a typical scheme of the ALC system, simple and efficient.

Fig. nineteen
Regulations: The most noticeable part of the amplifier is the control panel, it is the most difficult. There are many ways to locate and control the device. How easy there is a control panel depends on the developer and manufacturer.
There are ready-made boards that can be purchased and installed in an amplifier, but it is a bit wrong, because the reinforcement itself from scratch is much more interesting, however, for a beginner is a way out. Remember than the harder the device, the harder it is to manage and repair it. Simplicity and reliability - that's what you need to proceed when developing an amplifier. If the designer wants to create a fully automated amplifier and feels that he can cope with the task, the flag in his hands ... It will be difficult, and there will be problems, problems ... for beginners I advise, build the simplest, reliable, without frills amplifiers. After build simpler, there will be more complex devices, more elegant.
So look at the problem: "You are a developer engineer, you decided that you will do the device, no matter how much time and effort it does not require!"
Afterword:Nowadays, when it is easy to buy and exploit amateur equipment, what you want, it is easy to forget about the satisfaction that brings independent production. The one who buys and then plays an expensive toy, never experiences this feeling. Those who, nevertheless, want to test him, attach their own hands and head and make their HF amplifier, as our colleagues predecessors were made at their time and a real article was dedicated. It is impossible to describe in words the sense of completion, executed debt, satisfying from the experience gained. And also acquire something new in the process ...
If you have questions, I will gladly share knowledge and experience with you if you wish this sincerely.
73 de Matt Ericson, KK5DR
Free translation from English: Victor Besedin (UA9LAQ) [Email Protected]
tyumen November, 2003

From the above, it can be seen what features only one of the elements of the power amplifier should be possessed - an aode throttle.
First of all, to satisfy all the listed characteristics, it is necessary to understand what the length of the wire is needed, which the throttle is wound. In no case cannot be used even the proven data on the number of turns and apply them with a frame of another diameter. The main approach when choosing a wire length - it should not be a multiple half-wave on any of the working ranges used. There are several options for the manufacture of anodic choke. We give two of them most common in amateur practice.

First option:
It is clear that, working with high-frequency voltages, a framework will be required for winding anodic choke from the corresponding material - radiopharmal, fluoroplast, and the like. Having at its disposal a suitable framework, you can use the data of the anode throttle from any known and proven design and must, know the diameter of its frame and the number of turns, determine the length of the wire. Then check the obtained value to match the LN / 2 wire length inequality for each range. If everything is in order and the length of the wire is suitable, the number of turns should be counted according to the following formula
WD2 \u003d WD1 D1 / D2, GDE
WD1 is the number of throttle turns with a diameter of D1;
WD2 is the number of rotes of the throttle diameter D2;
d1 [mm] - choke frame diameter from description;
d2 [mm] - The diameter of the existing frame.
No less important to know the diameter of the wire for winding. It can be determined from the ratio
D \u003d 0.46 SQRT (Ia) [mm], where
la [A] is the maximum anode current (constant component).

Here is considered, the so-called partitioned subtle anode choke. These include chokes wound on the frames with a diameter of 16 ... 20 mm. But there are also "thick" chokes, whose frames have a diameter of 25 to 30 mm and more. These chokes have their own features and use them, as a rule, in the industrial equipment of high power.

Appointment and design of chokes

What is choke?

Electric choke - a device that is a coil of inductance and intended to limit the variable component electric current. In other words, if the current in the electrical circuit contains a constant and variable component that the throttle is consistently included in this electric chaindue to its inductance and greater resistance for alternating currentIt significantly reduces it, and on the constant component of the current, it affects the minimum, due to the low resistance of the DC.

Fig. one

Chokes allow to store electrical energy in a magnetic field. Typical application - smoothing filters and various selective chains. Their electrical characteristics are determined by the design, properties of the magnetic pipeline material, its configuration and number of turns of the coil.
When choosing a throttle, the following characteristics should be taken into account:

required inductance value (GN, MGN, ICGN, NGN);
maximum coil current;
admission (value of deviation from the initial value) of inductance;
temperature induction coefficient (TKI);
active resistance of the wire of the choke coil;
the quality of the throttle, which is determined at the operating frequency as the ratio of inductive and active resistance;
frequency range Coils.

Depending on the frequency range, high-frequency and low-frequency chokes differ technically different

High-frequency chokes are divided into two types:

with constant inductance;
with variable inductance, due to the adjustable ferromagnetic core.

The first type is used, as a rule, in the input chains of telephone sets, in smoothing filters, in the supply chains of RF equipment. The second type of coils is used in resonant chains - HF, receiving paths and transmitting devices.

In the tubing amplifiers of sound frequency, high-frequency chokes are applied extremely rarely. As a rule, their use can be predetermined by circuitry of output cascades, built on high-frequency high-power feeds, predisposed to self-excitation on radio frequencies.

Structurally high frequency chokes are performed in the form of single-layer or multi-layer coils. High frequency throttle designs are shown in Fig. 2. For long chokes ( a, B.) and medium ( b, B.) The waves applies a partitioned multi-layer winding. Chokes for short ( g.) Waves and for meter ( d.) Waves usually have a single-layer winding - a solid or compulsory step. As a frame, ceramic rods from SU-0.5 and SU-1.0 resistances are often used.

Fig. 2.

The high-frequency throttle can be made independently by winding the required amount of turns, to obtain the desired inductance on the ceramic or fluoroplastic core. Calculate the required number of turns can be calculated by the formulas in the section

It is better to use, manufactured by the industry HF choke. They have a clear bright color marking and are distinguished by high quality.

Fig. 2.

Designed to suppress the low-frequency component of the AC power supply and its harmonic. Figure 3 shows a low-frequency throttle, the inductance of 3 GNs with a current of the addition of 120 mA.

Fig. 3.Low frequency industrial production choke

Throtes are better, and the easiest way to use factory, preferably from the old lamp televisions Temp-6, Temp-6M, Temp-7, Rubin-102, avant-garde, Belarus, or other similar in the characteristics of old TVs. But if the task is to make a lamp amplifier high Quality And with their own hands, the choke will have to calculate, according to the method below, and make it yourself. A fundamentally new approach in modern tube circuit equipment may be the requirement of mandatory adjustment of the feed filter chokes into the resonance to the frequency of 100 Hz. This is necessary to increase the efficiency of filtering the straightened voltage.

Calculation of low-frequency throttle for anodic power supply

The throttle is an important element of the power supply unit of the lamp amplifier. Together with electrolytic capacitors, it is part of the P - shaped low-frequency filter and becomes an indispensable element in the anode power supply chain of the HI-END amplifier. Depending on the power characteristics of the amplifier and its qualitative indicators, the dimensions of the choke can vary greatly and reach up to half the sizes of the power transformer.

Some parametersfound in the calculated formulas:
F.- frequency Hz;
S.c. - Core sections area, square. cm;
TOfrom - Core filling coefficient Steel;
S.oK. - window cross section of the window, square. cm;
TOoK - coefficient of filling windows with copper;
INt. - maximum induction in the core, TL;
J. - current density in wires, a / sq. mm.
I. - d.C. In the winding of the choke, A.

The main parameter of the throttle is its time constant, inductance ratio to winding resistance L / R.. The higher this value is required, the more the dimensions of the magnetic pipeline should be that the wire of the desired diameter and the length fit in the core window.

Calculated by the already known formula:

With the consistent degree of constant additions, the inductivity is obtained by the maximum at a certain length of the non-mag-long gap lZ. . The equivalent magnetic permeability of the core depends on the magnitude of this gap:

In the presence of permanent additions lZ. No longer an independent variable. The key value in calculating chokes and transformers is the degree of additions or the number of robust ampermns ( aw0. ).

Magnetic field tension communication formula with engineering magnitude aw0. , shown below:

The proposed calculation algorithm is based on an experimental graph of magnetic permeability dependence on aw0. Figure 4.

Fig. fourExperimental graph of the dependence of the initial magnetic permeability from aw0.

These graphs correspond to the mass brands of steels. High-quality steel has several times a large magnetic permeability, but in most cases it is not necessary to count on it. The graph shows the dependence of the initial (i.e. in the absence of an alternating magnetic field) of the magnetic permeability on the tension of the magnetic field, expressed in the amperm in the centimeter. In the system system, tension is measured in amps per meter. It should be remembered that the points on the graph correspond to different gaps. Higher tensions require greater gap. At the beginning of the calculation of the magnitude aw0. and correspondingly, μ z. Not known. The number of turns in windings can be obtained by the method of consecutive approximations by the formula:

For this, the formula is substituted by the transformer parameters, the desired inductance and trial quantity μ samples According to the resulting number of turns, the degree of applied aw0. . On schedule μ (aw0. ) located μ z. Instead of graphs with machine calculations, approximating equations can be used:

For hot-rolled steel

For cold-rolled steel

Prone μ samples Corrects and again calculates the number of turns. This procedure is done several times until the change in the number of turns from the miscalculation to the miscalculation will not be insignificant (a few percent). In most cases, two or three passes are enough. If the new value is more old μ samplesT. μ samples It should be increased so that it becomes a little more μ z. and vice versa. At the end of the calculation you need to make sure that the resulting L., N. Satisfy the requirement of constructive realizability. To do this, the maximum wire section is calculated. S.which can be placed in the window

The current density in the copper conductor of the throttle winding is calculated by the formula:

If current density J. does not exceed the usual 1.5-2 A / sq. mm, then the calculation can be considered over, since it does not need to accurately comply with the shell resistance specified. The number of turns should not exceed 3500-4000. If necessary, select another type of magnetic pipeline and repeat the calculation. When assembling a wound throttle, it is necessary to put in the gap of the non-magnetic gasket of the desired thickness. Exact compliance and selection of the gap size is only necessary for output transformers. For chokes, the accuracy of the empirical formula below is quite sufficient. The magnitude of the gap is calculated in mm:

Winding of choke coils does not have features. In most cases (for chokes of power supplies) there is no need even in interlayer isolation. The winding is usually under high potential, so it should be well isolated from the core. The impregnation of chokes is usually needed to avoid the buzz. The results of the calculation of the throttle on a very common and cheaper core from the output transformer of the lamp television W 16x25 with the window size of 16 x 40 mm are shown in Table No. 1:

Table №1

SC	4 kb. cm.
Sok.	3.84 KB. cm.
LC	10.6 cm
L0.	12.84 cm.
Kok.	0,34
I0.	120 MA.
aw	29,4
μz.	171,8
N.	2600 VIT
L.	5.51 GN
D.	0.25 mm
R.	116.3 0m.
P.	1.67 W.
lZ.	0.25 mm