The article is devoted to some of the features of building an amplifier on the most powerful and relatively small-sized lamps from the series known as "television". Considerable amount of reasoning is given in the text on related topics. Oddly enough, it is the adjacent areas that are extremely important to ensure the resulting quality of the amplifier. For example, it is the matching transformers that radically affect the sound, not the lamps. Serviceable lamps have practically no effect on the sound amplification characteristics. However, the lamps look beautiful and glow in the dark. And this is probably why the names of the lamps give the impression of decisive signs of the quality of the product. Already by appearance the solidity of the pot-bellied glass cylinders 6P45S is noticeable. Taking into account the power reserve traditional for sovdep lamps, it is possible to build a push-pull amplifier in which the scattering of the anodes can be increased to 45-50 watts. With such a large dissipation, the heat release will be enormous. This is of course a disadvantage. But, according to the GURU, the sound quality in modes close to A, you can get excellent. My attitude to such extreme is cautious. I'm not a supporter of the "A" mode in a tube amplifier. The second inconvenience of 6P45S can be considered the upper location of the anode outlet. In addition, the incandescent current is 2.5 amperes and the lamps heat up very much, which is also inconvenient. Therefore, a structure with a closed mesh top, or at least with crossbars, should be envisaged. For heat dissipation, we can recommend the use of low-noise computer fans at + 12VDC, which automatically turn on when the case heats up over 50 degrees.
Given the hefty wattage of the lamps selected, close attention should be paid to the design of the power supply. It should be noted that the traditional frivolous attitude of many TV viewers to the power supply of a tube amplifier is not suitable. An amplifier's power supply is its power plant, the heart of its design, and the source of all its success. The power plant must be created extremely thoroughly and precisely according to the block principle. And novice lamp-builders need to learn how to quickly and accurately calculate the required power of power transformers. It is better to focus on the maximum consumption mode and approximately calculate the total power of the transformer windings. First, you need to calculate the power dissipated at all anodes. In the limit mode, 4 lamps can dissipate 40x4 = 160 watts. Small lamps dissipate 4-6 watts in the anodes. Then you need to add to the heap the power that is planned to be sent to the load, for example, 50x2 = 100 watts. Filament circuits of powerful lamps consume 2.5x4x6.3 = 63 watts. Small bulbs will consume 12-14 watts. In total, the resulting consumption is 260 + 75 = 335 watts. The design value of the efficiency of a two-channel amplifier does not exceed 30%.
The power of power transformers can be somewhat reduced, since the maximum mode is used extremely rarely. When designing transformer power supplies, the large overload capacity of transformers is taken into account. For this reason, they usually do this when creating serial amplifiers, reducing the installed power of the PSU by 20-30% percent. Such a solution is quite permissible, however, for high-level amplifiers manufactured in a single copy, it is better not to do this. In addition, the incandescent power cannot be reduced, since heat losses cannot be fooled. Nor should the value of the installed power of the transformers be overestimated, since this unjustifiably increases the weight of the product. Remember, with the calculated power value of the power supply transformers, the ratings obtained correspond to high temperatures exploitation. Therefore, heating the transformers to 60 degrees should not come as a surprise to the designer. If in the head of the viewer there is an idea that the iron should be cold, then all the power should be doubled and prepare for the fact that the mass of the 15 W amplifier will become 35-40 kg.
In my opinion, the most promising circuit solution for push-pull tube amplifiers of high energy efficiency should be considered a matching stage based on a differential pair of transformers. The advantages of such a scheme completely cover its disadvantages. Any reasoning about hand-to-hand winding of matching transformers in a tube amplifier, I attribute to perfectionism. To me, this seems to be one way of self-consolation for the designer or one of the marketing steps in justifying the extreme cost of the amplifier. Self winding is a harmful excess and stupidity. By itself, hand-to-hand winding of transformers into a push-pull amplifier is not technically difficult. But making a symmetrical pair is no longer an easy task. Manual manufacture of an identical four of transformers for differential series connection is a project unthinkable in complexity. For single-ended amplifiers, the creation of symmetrical trances is realistic, since using Ignatenko's technology, you can use hammering when adjusting the air gap on the glue, at the joints of the cores. The characteristics of iron for transformers with a gap are not of particular importance, since the gap damping the magnetic properties of the core by a factor of 1000 or more.
An example of a first level schema is shown below. Here the anode voltage is quite high, and the grids are connected according to an ultralinear scheme to the symmetrical 42% taps of the transformer windings, relative to the center of the anode supply of +330 volts. This is not good, because, in theory, the second grids should have a voltage lower than the anodes. In practice, such an inclusion, along with the advantages of the ultralinear scheme, may have a disadvantage - the appearance of additional distortions described by Ignatenko. Therefore, we can consider an alternative version of ultralinear inclusion according to a different scheme, shown in the article below. A feature of these particular circuits is the inclusion of an output stage with a buildup from cathode followers. Amateurs know that television lamps are of low sensitivity. Therefore, you have to resort to additional tricks, use preliminary stages with dynamic loading, or install additional powerful drivers. The use of a pinch-coupled circuit somewhat complicates the setup, but avoids the use of blocking capacitors. A practical repetition of the schemes shown here should be performed using 6N1P lamps, with carefully selected halves according to the symmetry condition. And the output lamps in this version must be selected according to the equality of the bias voltage. There are general guidelines for building high-end push-pull amplifiers. You need to use symmetrical lamps, while hemorrhoids will be much less. And in these specific schemes, this is no longer a wish, but a demand.
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There are no gaps in high-performance matching transformers, so the result depends only on the quality of the winding, the equality of turns, the quality of assembly and the nonlinearity of the characteristics of the iron. The last two conditions are extremely difficult to ensure in reality. Here, on the fly, you need to lay the discrepancy of the operating parameters of about 10%. And this discrepancy can be established in practice only by measuring the finished product. And when a discrepancy is found, then the finished trance can be safely carried to the trash heap, since such a spread will not allow building an energy-efficient amplifier. For the requirement of jewelry accuracy, you can go along the path of selecting symmetrical pairs from a bunch of bourgeois output transformers, but how much it will cost money is hard to imagine. You need to understand that a very good result in the amplifier gives a discrepancy in the load characteristics of the transformers of no more than 2-3%. Moreover, it is curious that such a difference in currents XX does not at all guarantee the equality of the EMF of the windings when they are connected in series! This feature is described in my method of selecting transformers, here on the site. As a rule, out of 4-5 transformers with approximately the same no-load current of 10-12 mA, only two products provide a symmetrical pair. The rest disperse in 8-10% and they have to pick up a pair of adjacent values of 8-10mA or 14-16mA for currents XX.
The explanations presented here show the depth of the chasm in the path of building a high quality, energy efficient amplifier with a differential pair of output matching transformers. If the requirements for symmetry are somewhat roughened, for example, up to 15-20% of the EMF discrepancy, then the selection of pairs is much easier to perform. At the same time, at the stage of tuning the amplifier, the curvature of the operating system for alternating current must certainly be straightened by hand-to-hand instrument adjustments. It will not be possible to find a direct connection with the quality of sound amplification here, since it is not there. You don't have to think that an amplifier with crooked transformers will sound much worse. Not to notice this by ear, even at medium power. Lamp circuits are generally auto-balanced and tolerate curvature easily. And the adjustment allows you to equalize the characteristics of the sound path. You just need to be aware that the limiting operating parameters of such a design will really be less. For example, a car with an inscription Bugatti at a speed of 299 will not go along the highway to Abakan. The available speed limit will be only some 150 km / h. I declare with full responsibility that blind listening to amplifiers with lamps operating in different areas, even of very different operating characteristics, will not be reliably identified by experts. There are no such people who distinguish between different spectra of harmonics, beautifully mixed within the musical range. Using the instruments, it is certainly possible to establish the difference in spectral composition. But only by instruments. Therefore, for the experts, there will be only smacking lips and shaking the head, they say they like it, but they don't like it. Moreover, it is not a fact that specific people with a worn out attitude will like a smoother frequency spectrum, without outstanding harmonics.
Novice designers should remember that in reality the situation is even simpler. If the requirements for the product are reduced even more, then when tuning the amplifier, it will be possible to straighten out a more significant curvature, or at least smooth out its consequences. In this case, the lamps themselves can be curves. But even using gnarled bulbs, you can push them to different performance characteristics. At the same time, being in curved modes, the lamps will be able, within reasonable limits, to deliver the power of an undistorted signal to the load, which is quite sufficient for comfortable perception of sound. The difference is easy to see in the comparison shown below. A beautiful and compact Chinese jack with an inscription of 12 tons, made without tweaks, will easily lift the Kukuruzer, but it should not be used for Kamaz. After all, he will raise Kamaz only once. And if such tough testing is not done, then the driver of the Kukuruzer will be pleased with the small Zhiguli jack dimensions and the inscription of 12 tons and will never know the reality. This is an ordinary marketing, oh, a mistake in the text, this is an ordinary deception.
An example of a Layer 2 circuit is shown below. The division into levels is, of course, conditional, the output transformers are exactly the same. The number of windings is fixed. And it is a matter of taste to adapt these windings to cathode OS or mesh. The main thing is to perform error-free wiring, for which there is an ordinary "scientific poke" method. A properly assembled and efficient amplifier is sufficiently sensitive to transformer feedbacks, therefore, any of their incorrect inclusion is fraught with a sharp deterioration in the regime. And there is only one option for the correct inclusion of the windings. This is what you need to find when setting up an amplifier with an OS.
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In general, we can conclude that the 6P45S lamp is an excellent motor suitable for building a dynamic and almost omnivorous amplifier. It is absolutely feasible to double the tetrodes to increase the power. We must be very careful about the authors of the pictures, in which, instead of the classic tetrode, the 6P45S lamp is depicted in the form of a pentode. This is a wrong image. Hence, one should proceed in assessing the reliability and the resulting authority of the circuitry and the author's reasoning. In the continuation of this article, another article is planned on the site - about the features of the selection of 6P45S lamps.
At the end of the presentation, I dare to assure you that all the pieces of iron described on the site can be purchased for rubles. In order to buy an amplifier based on 6P45S at a price of 45K, the buyer just needs to negotiate with the seller, preferably in Russian. The algorithm for fulfilling obligations under supply (purchase and sale) contracts is as follows. The interested party calls me on the phone at a reasonable time in the Krasnoyarsk time zone. We are vividly discussing the details of the contract. The buyer then credits my telephone number payment of 1% of the purchase price. This is a sign of the buyer's seriousness and allows me, if necessary, to promptly call back. After discussion on the phone, I send to email partner's commercial offer, with the characteristics of the goods, warranty obligations and delivery times. Further, by correspondence, the negotiations are completed and the buyer transfers 20% of the purchase price to my account. The remaining 79% of the amount is transferred to the supplier's account after the buyer receives a notification about the readiness of delivery. Please remember, the advance payment for the hardware is 100%. Therefore, the buyer can immediately transfer the entire amount, already at the first stage of the correspondence, but only after my written approval. There is no movement on my part without prepayment. Tips are free. Delivery of pieces of iron by mail of Russia or a transport company at the expense of the buyer. Pickup is possible by agreement. If the buyer refuses the transaction, no refund will be made.
Evgeny Bortnik, Krasnoyarsk, Russia, November 2017
- I present a device with a pre-amplifier and a sound power amplifier integrated into one housing with perfect sound quality. The lamp has stabilized modes, in stereo it outputs a power of 350 W for each channel. In mono mode, if four 6p45C lamps are installed in the final stage, there will be 700 watts. The maximum power is indicated here - measured before the appearance of the limitation on the sinusoidal audio signal.
The picture is clickable. A large-scale scheme can be taken → Here
Natural musical power will be slightly less. If two lamps are installed in the output path, then naturally the power will also be halved. When assembling a tube sound amplifier, no special selection of tubes is required, since there is an adjustment function for each 6P45S tetrode. Therefore, everything is simple - take the diagram and start doing it.
Amplifier on tubes 6P45S
The tube amplifier assembled according to this scheme on 6P45S tetrodes has been repeatedly tested and works great. Two devices were made in a stereo version, if we consider it as mono, then we get four devices. This universal circuit makes it possible, without changing anything in it, to assemble the most simple lamp tube, such as, for example, an end amplifier and work with the remote control. Or make more complex designs, for example: with a built-in timbre block, or even more perfect - install additional input modules for connecting electric guitars, microphones or synthesizers.
Tube amplifier circuit, also allows you to make the amplifier both monaural and stereo. In addition, it is possible to install almost any amplification tube without making changes to the circuit. For example: instead of one 6P45S, 2 pcs can be used without problems. 6P36S or 6P44S. Based on this, it is easy to calculate: if the output stage is mounted on four 6P36S lamps, this will be equivalent in power to two 6P45S.
Output transformer
Also, the output transformer will work stably with an output stage consisting of both two 6P45S lamps and four 6P36S lamps. The output trance from the Soviet radio broadcasting amplifier U-100U4.2, which has an ideal frequency and excellent quality, has shown itself well in operation. If you find such a transformer, then it will remove a laborious problem for you - you will not need to rewind the output from scratch. In addition to this, the sound power turned out to be within 175 watts.
In this design, some of the nodes recommended by well-known radio amateurs were used. In particular, presented here tube amplifier circuit incorporates such output transformers. But you can install those that you have available and suitable in terms of parameters, everything will work fine.
Voltage regulator
A characteristic feature of this amplifier modification is the use of the stabilization mode function. The use of such stabilization eliminates the possibility of a negative impact on the device in case of strong drops in the mains voltage. Also, this tube sound amplifier is not sensitive to voltage surges in the power supply circuit, at which all modes of radio tubes work abruptly.
At the stage of assembling the structure, the apparatus was tested with and without stabilization of the modes - a huge difference between the two options was revealed. The device with a stabilizer was far superior to the second option in terms of reliability and stability in operation, clarity of the sound picture, and so on. Don't skimp on a pair of transistors. therefore the best solution will be for you if you additionally assemble voltage stabilizers. As a result, you will be rewarded with high quality amplifier performance and superior sound.
Installation of stabilizer transistors
For the convenience of installing transistors in the stabilizer circuits, you need to use transistors in a plastic case, which are easiest to attach directly directly to the amplifier case. Thus, providing good thermal stability to the transistors. In this circuit, I used transistors from a line scan and a power supply for branded TVs.
The constant supply voltage in the preliminary stage supplied to the filament circuit of all the lamps installed there coped perfectly with all kinds of manifestations of background distortion and noise. This is actually not audible at all. Naturally, I distributed the ground points that run from one stage to the next. And the last point is brought out to the common body at the cathode of the output tetrodes, and at this point the power wire converges high voltage by "minus". Pay particular attention to correct installation.
The use of the SRPP circuit (in the Russian sense - a cascade with a dynamic load) in the pre-amplification stages is completely justified by its resistance to overloads, excellent quality, and low resistance at the output.
The presented photos show the finished tube full amplifiers: The first is a full 700 W stereo amplifier; the second is a power of 300 watts.
The schematic diagram of this single-ended amplifier on a 6p45s lamp was developed by S. Sergeev and successfully repeated by many radio amateurs. I was no exception :) Moreover, the most common parts and lamps are television, which means they can be easily found on radio markets or in TV workshops. But of course, it is preferable to install new lamps, since in this case the power and sound quality will improve.
The 6p14p lamp is an output pentode, which itself is capable of developing a watt. But in this circuit it stands as a pre-amplifier for the more powerful 6P45S. The 6p45s lamp at a fixed bias does not behave stably (current is floating). With autobias, high power dissipation across the cathode resistor. Choose for yourself which option to choose. There are pros and cons everywhere. A negative bias is applied to the grid from a separate low-power transformer, if you do not want to wind up the TS-180.
In its version, as a power one in the power supply, I installed a TCA-270 transformer. Output audio used tshs-130 without rewind.
Input sensitivity is sufficient for connecting to a computer or MP-3 player. The maximum output power of this amplifier is over 10 watts. Namely "honest" 10 watts, not Chinese, which can be safely divided by ten :)
A schematic diagram of a power supply for a single-ended amplifier is shown in the following figure.
Tuning the tube amplifier consists in selecting the resistor R4 in the circuit of the second grid of the preamplifier stage to the maximum gain. And the adjustment of the anode current of the output 6p45s is carried out by the trimming resistor R10 according to the voltage drop across R9. It should be about 0.15-0.18 volts, which corresponds to currents of 150-180 mA.
It is better to make the case of metal, for shielding from interference and interference, but I did not find metal - I had to cut it out of wood.Input / output jacks and connectors are all standard to reduce construction costs.
UM on two GU29
V. Milchenko RZ3ZA
The amplifier is assembled on two, parallel switched, GU-29 lamps. The amplitude of the input signal is 1 ... 1.5 volts. Anode current is 400 ... 450 ma. Output power at a load of 75 ohms is 150 watts.
In the transmission mode, a voltage of -15 volts is applied to the KT920B transistor, the quiescent current, the quiescent current of the transistor (without a signal) is 120 mA. Within small limits, it can be adjusted by selecting a resistor R3. Transformer T1 is shunted with a 2k resistor. The quiescent current of the lamps is set automatically by two series-connected Zener diodes D815D and for two lamps it is 70-80 mA. The lamps are placed horizontally in a 300x300x80 mm housing. The T1 transformer is wound on a cylindrical frame with a 600NN ferite core.
Literature: magazine "Radio amateur" No. 8 1997
PA on two lamps 6P45S
Hybrid PA with transformerless power supply
E. Golubev, RV3UB
PA with transformerless power supply and protection
For example, the diagram of a PA with a power supply protected from phase reversal with zero is shown. The whole article can be read: the magazine "Radio" 1969 №3 p.19
POWER RADIO STATION 1 CATEGORY
Literature: "Radio" 1979 No. 11 G. Ivanov (U0AFX)
Transformerless power supply in the UM
PA for CB radio station
This power amplifier is designed for stationary operation of a portable radio station. In this case, the signal from its output goes to the input of the amplifier through a coaxial cable. The power of the portable radio station with an input impedance of 50 Ohm of the power amplifier is 1-2W. This power amplifier develops power up to 30-40W. the output is designed for a 75-ohm antenna.
The amplifier circuit is shown in the figure.
The signal from the output of the transmitter goes to the input X2 to the input of the VL1 double lamp GU-29, the signal goes to the control grids of this lamp. R7 brings the amplifier's input impedance to 50 ohms. The anode load of the lamp is the choke L2, from which the signal goes to the U-shaped filter L1 C3 C4 and then goes to the antenna. The output stage of the transmitter is equipped with a SWR meter that allows you to measure SWR both direct and reflected. This makes it possible to adjust the output circuit using capacitors C3 C4.
The power supply is transformer, it contains 2 rectifiers and three parametric stabilizers.
L1 is wound with a copper wire (bare) with a diameter of 2 mm, without a frame, the winding diameter is 25 mm, the winding length is 22 mm, the number of turns is 8. L2 is wound on a frame with a diameter of 20 mm and contains 150 turns of PELSHO 0.25, the winding length is 80 mm. L3 L4 are wound on resistors R2 R4, they contain 5 turns of PEV 1.0 each. L5 L6 - chokes DM-0.5. T1 - 6 turns of PEV 0.31 with a tap from the middle of the coaxial cable wound on the inner core, which goes from L1 to the output connector (at the place of winding, the shielding braid is removed).
T2 is wound on a magnetic circuit Ш25 * 32, winding 1-1030 turns of PEV 0.25, 2-1300 PEV 0.25, 3-60 turns of PEV 1.0 with a branch from the middle, winding 4 contains 175 turns of PEV 0.2.
The amplifier is mounted in metal case volumetric installation. If necessary, it is necessary to carry out heat removal using a fan to blow off the lamp.
R8 sets the quiescent current of the lamp between 15-17mA. the alternating control voltage supplied to the lamp grids (U on R7) should be about 10V and not exceed 15V.
Amplifier on tubes 6P42S
The difficulty of obtaining average power levels (about 100 W) in transistor silos forces us to look for other solutions. It can be the same as suggested by the Muscovite V. Krylov (RV3AW). He created a push-pull amplifier based on two 6P42S tubes, operating at a supply voltage of only 300 V. The output power of the amplifier is 130 W with an input power of about 5 W.
Push-pull switching on of lamps allows significantly (up to 20 dB) to reduce radiation at the second harmonic in comparison with a conventional amplifier. In the anode circuit of the lamps, a broadband transformer T1 with a transformation ratio of 4. As a result, the HF voltage amplitude at the output P-circuit is halved and it becomes possible to use a standard KPI from a broadcasting receiver. The simplicity of the device and the availability of the element base allow us to recommend this power amplifier for repetition. The diagram is shown in Fig.
The L2 coil is made on a plastic ring (standard size K64x60x30) with MGTF wire with a conductor section of 0.5 mm. Taps are made from 2, 4, 8, 12 and 20 turns. The transformer T1 is made on a magnetic core of two rings of standard size K40x25x25 from ferrite 2000NN. The windings contain 12 turns of MGTF wire with a conductor cross-section of 0.5 mm. The T2 transformer is made on two ferrite (2000NN) rings of standard size K16x8x6 folded together. Each winding consists of 8 turns of MGTF wire with a conductor section of 0.15 mm2. The winding of T1 and T2 was carried out simultaneously with three wires.
Transformerless RA on GU-29
I.Avgustovsky (RV3LE)
The idea of building a push-pull amplifier based on vacuum tubes is not new, and the circuitry of this amplifier, in principle, is no different from the circuitry of building push-pull amplifiers on transistors. It should be noted that current lamps work best in this circuit, i.e. lamps with low internal resistance, which are capable of providing a significant pulse of anode current at a low supply voltage. These are 6P42S, 6P44S and 6P45S lamps. However, I also managed to build an amplifier with good characteristics on a GU-29 lamp.
The range of amplified frequencies is 3.5 ... 29.7 MHz.
The power supplied to the anode circuit is 150 W.
The efficiency is 65%.
Output power at the equivalent antenna 75 Ohm in the ranges:
o 3.5 ... 21 MHz - 100 W;
o 24 MHz - 90 W;
o 28 MHz - 75 watts.
The power consumed from the mains at the rated voltage in the mains and the maximum output power is 200 W.
Dimensions:
o width - 160 mm;
o height - 150 mm;
o depth - 215 mm.
Weight - no more than 2 kg.
A distinctive feature of this amplifier is its transformerless power supply circuit. The advantages of such a power scheme are obvious - with a power input of 150 W, taking into account the efficiency of the power supply, a power transformer with an overall power of at least 200 W is required. In this case, the dimensions and weight of the power source itself are comparable to the parameters of the power amplifier itself and far exceed the dimensions and weight of an amplifier with a power input of 500 W on 6P45S lamps.
I made this amplifier as an experimental one back in 1994, but from the very first day of operation it showed itself so well that it works to this day without any alterations. During this time, more than 10,000 QSOs were made on it. All correspondents invariably note the excellent signal quality. Despite the fact that my antennas are only 2 ... 3 meters away from the collective television antennas, TVIs are completely absent.
I also want to note that the GU-29 lamp in this design is operated in a very severe mode (input power - 150 W), but despite this, for two and a half years of operation, I did not find any deterioration in power characteristics. Consider schematic diagram(fig. 1).
The input signal is applied to the primary winding of a broadband transformer based on the T1 line. The non-inductive resistor R1 is the active load of the power amplifier of the transceiver itself and allows you to obtain a linear frequency response of the latter.
The amplified antiphase signal from the anodes of the lamp goes to the transformer T2, at the midpoint primary winding which is supplied with anode voltage. The load of the amplifier is switched on through a conventional P-circuit, the signal to which is removed from the secondary winding of the transformer T2.
The amplifier is powered through a rectifier assembled according to the voltage doubling scheme on diodes VD1, VD2 and capacitors C10, C11 (Fig. 2).
The screen grid voltage (+225 V) is stabilized. The bias voltage is obtained from a separate rectifier VD5, C9 from the secondary winding of the filament transformer T3.
You should pay special attention to the fact that none of the sources supplying the amplifier (~ 6.3V, 0, -Ucm, +225 V, + 600 V) is not connected to the chassis! The chassis of the amplifier is used as a common wire for high frequency only.
Amplifier parts and designs
Since the power supply circuits are galvanically isolated from the chassis through transformers T1 and T2, special attention should be paid to the carefulness of their manufacture. Transformer T1 is wound on a ferrite ring of the M30VCh brand with an outer diameter of 16 mm (20 mm is possible). Previously, sharp edges are removed from the ring with fine sandpaper. Then the ring is wrapped with at least three layers of fluoroplastic tape. The winding of the transformer is carried out simultaneously with three wires in fluoroplastic insulation MGTF-0.12 without twisting. The number of turns is 12.
The T2 transformer is similar in design to T1, but is made on two M30VCh rings folded together with an outer diameter of 32 mm (36 mm is possible). The windings of the T2 transformer also contain 3x12 turns of MGTF-0.14 wire without twisting. The ends of the windings are fixed with threads. You should not use polyethylene film as insulation due to its non-heat resistance.
I do not give the parameters of the P-contour, they are easy to calculate using the available methods. In the author's version, the L3 coil is wound on a fluoroplastic ring with an outer diameter of 70 mm and a cross-section of 15x15 mm2 with a silver-plated wire with a diameter of 1.5 mm and is held with its taps on a ceramic biscuit of the SA1.2 range switch. Capacitor C5 is an air-dielectric trimmer type KPV-150. C8 - standard two-piece PBC 2x12 ... 495 pF from broadcast receivers.
All blocking capacitors C1 ... C4, C12 ... C14 are of the KSO type for a voltage of at least 500 V or similar with a nominal value of 0.01 ... 0.1 μF.
In the power supply (Fig. 2), the VD1 and VD2 diodes are KD226G or KD203A, which allow a large current pulse, which is inevitable at the moment of power-on, since this design does not have a large inductance in the form of a power transformer. The charging current of capacitors C10 and C11 reaches tens of amperes within a few milliseconds, therefore, a resistor R6 is installed to protect the diodes VD1 and VD2 from breakdown. Its value is not critical and can range from 330 Ohm to 1 kOhm. A few seconds after turning on the amplifier, it is shorted by the SA3 "Anode" toggle switch. Resistors R7 and R8 serve to equalize the voltage across capacitors C10 and C11.
Transistor VT1 and Zener diodes VD3 and VD4 are mounted on small heat sinks isolated from the chassis. Trimmer resistor R9 - any type, but with good insulation. Filament transformer - with an overall power of at least 20 W and with well-insulated windings.
Anticipating the question of readers about possible replacements of ferrite rings for transformers T1 and T2, I want to say the following: rings with a permeability of 30 HF can be replaced without damage to any of the specified standard sizes with a permeability of 20 HF ... 50 HF. I have not experimented with rings with a permeability of 100 NN ... 600 NN, and rings with a permeability of 1000 NN ... 3000 NM will obviously not work here.
The power supply unit and the amplifier lamp have galvanic contact with the mains, so care should be taken during the setup process. Once again I draw your attention: the "0V" circuit must not have contact with the chassis! The input (before T1) and output (after T2) amplifier circuits are absolutely safe and must be connected to the chassis according to the diagram.
Linear Power Amplifier for SSB / CW / AM
With an input power of 200 W, the output power is 120 ... 130 W. The amplifier operates on two GU-50 pentodes according to the scheme with three grounded gridsThe input impedance of the amplifier is 50 ... 70 Ohm, which allows it to be connected to the exciter with a piece of coaxial cable with the same characteristic impedance.
To achieve a current of 200 mA at an anode voltage of 1200 V, an excitation power of 7 ... 10 W is required. The quiescent current is several milliamps. The peak power (input) can be increased by amplifying SSB signals to 400 W without hazard to lamps, since the average input power will be about 200 W. Choke DR1 with an inductance of about 300 ... 500 μH should be designed for a current of 200 ... 250 mA
I bring to your attention an amplifier from Yuri Malyshev
Wideband amplifier designed for vocals or for mid-high frequency path in a 2-way club system.Can also be used as stage monitors.
Brief characteristics:
1.Frequency range 40-30000Hz (at zero)
2.Output power 2x170W (for outputs iron from TS-250 or PL20x40x100) On 6P45S lamps (preferably pairs) or 6P42S. You can use 4P44s, but already two in the shoulder and must be matched.
3.Sensitivity -0dB (0.775V)
4.Noise level -80dB
5. The harmonic coefficient is 1.5%, it is possible and much less with accurate balancing of the final stage.
6. Forced blowing of output lamps.
7.Power tr-r - paired TS-250 or twin on PL2040100 (preferable)
8. Execution "REC" - new
The circuit has been worked out and tested for many years. Several variants of amplifiers have been released (for 10 years about a thousand in Kharkov, under different names)
I will give you the output data, then I will write detailed measurements of it in the operation of the amplifier. And the correction from the calculated data is usually no more than 5% of the number of turns in the primary and secondary. Compared to your classics, I still check everything in a "live" product!
So, the iron from TS-250.TS-180, although the same in size, is much worse. Two frames made of fiberglass, although due to poverty (but rather laziness), you can take a frame from a press frame
On each coil, the primary with a wire of 0.355 -4 sections of 360 vit. Each section is two layers. On two coils, respectively, 2880vit.
Secondary 4-ohm 5sections 130vit each coil 0.45.Total 10sections. On top of each coil there is a home engine on the 8th 55vit.wire 1.06. It is easy to see that the coefficient of tr-tions on the 4th = 22.15
Insulation is desirable LAVARIL. Of the many hundreds of exits for 25 years, not one burned out, at least not seen such breakdowns.
Here I found a very interesting table on the detailed measurement of the amplifier with this transformer.
Briefly 28Hz-182W (output power) at Kg-6%.
28Hz-169W at Kg-3.4%
28Hz-156W already Kg-2.3%
30Hz -182W (4th load everywhere) -Kg-3%
40Hz-182W Kg-1.7%
1000Hz 182W Kg-1.3%
10kHz 182W Kg-1.3%
20kHz 182w Kg-1.5%
40kgk 182w Kg-2.0%
60kHz 156W Kg = 4.3%
100kHz approx 100W in the lamps, a blue glow is observed and it is after about 2 minutes. fails.
And in normal operation, it serves for years with a good Jamikon fan, for example, with a height of about 100mm. The height of the front panel of the amplifier is 3U-standard. Width-19 "(482mm).
The instruments then were the G3-102 generator, the C6-8 distortion meter, the C1-83 oscilloscope, and the V3-33 voltmeter at the output.
And here is the diagram of the output transformer. The primary color is red. In the section there are two layers of 0.355 wire, 180vit. in the layer.
Secondary grid feeding
