Matching devices per sq. range inurl guestbook. Antenna matching devices. Antenna tuners. Schemes. Do you need an antenna tuner

Modern transceiver technology, as a rule, has broadband paths, the input and output resistances of which are 50 or 75 ohms. Therefore, to implement the declared parameters of such equipment, it is required to provide an active load with a resistance of 50 or 75 ohms for both the receiving and transmitting parts. I emphasize that the receiving path also requires a matched load!
Of course, in the receiver you can't notice it either by touch, or by color or taste without instruments. Apparently, because of this, some "foaming at the mouth" shortwaves defend the advantages of old RPUs like R-250, "Krot" and the like over modern technology. Old equipment is most often equipped with an adjustable (or tunable) input circuit, with which you can match the RPU with a wire antenna with "SWR = 1 on almost all ranges."

If a radio amateur really wants to check the quality of the matching of the "transceiver input - antenna" circuit, it is enough for him to assemble the most primitive matching device (CS), for example, a P-loop, consisting of two KPIs with a maximum capacitance of at least 1000 pF (if it is supposed to check on the LF- ranges) and coils with variable inductance. By including this SU between the transceiver and the antenna, changing the capacitance of the KPI and the inductance of the coil achieve the best reception. If, at the same time, the values of all the elements of the control system will tend to zero (to the minimum values), you can safely throw away the control system and work on the air with a clear conscience and continue, at least, listen to the ranges.

For the transmitter path, the absence of an optimal load can end more sadly. Sooner or later, the RF power reflected from the mismatched load finds a weak spot in the transceiver path and "burns out" it, or rather, any of the elements cannot withstand such an overload. Of course, it is possible to make the silo absolutely reliable (for example, remove no more than 20% of the power from transistors), but then at a cost it will be comparable to the nodes of expensive imported equipment.

For example, a 100-watt silo made in the USA as a kit for a K2 transceiver costs $359, and a tuner for it costs $239. And foreign radio amateurs go to such expenses in order to get "just some kind of coordination", which, as the experience of the author of this article shows, many of our users of transistor technology do not think about ... Thoughts about matching the transceiver with the load in the heads of such grief radio amateurs begin to appear only after an accident in the equipment.

Nothing can be done - these are today's realities. Examinations for obtaining licenses and upgrading the category of an amateur radio station are often held formally. In the best case, the applicant for a license is tested for knowledge of the telegraph alphabet. Although in modern conditions, in my opinion, it is advisable to place more emphasis on testing technical literacy - there would be less "group sex for long-distance work" and "arguing" about the advantages of UW3DI over "all sorts of Icoms and Kenwoods."

The author of the article is pleased with the fact that less and less talk is heard on the bands about problems when working on the air with transistorized power amplifiers (for example, the appearance of TVI or the low reliability of output transistors). I competently declare that if the transistor amplifier is correctly designed and correctly manufactured, and during operation the maximum operating modes of the radio elements are not constantly exceeded, then it is practically “eternal”, theoretically, nothing can break in it.

I draw your attention to the fact that if the maximum allowable parameters of transistors are not constantly exceeded, they will never fail. Short-term overload, especially transistors designed for linear amplification in the HF range, can withstand quite easily. Manufacturers of high-power RF transistors check the reliability of the manufactured product in this way - they take a resonant RF amplifier, and after the optimal mode and rated power are set at the output, a test device is connected instead of the load. Adjustment elements allow you to change the active and reactive components of the load.

If, in the optimal mode, the load is connected to the transistor under test through a line with a characteristic impedance of 75 ohms, then usually in the device under consideration, the line segment is closed by a resistor with a resistance of 2.5 or 2250 ohms. In this case, the SWR will be equal to 30:1. This SWR value does not allow obtaining conditions from a complete break to a complete short circuit of the load, but the actually provided range of changes is quite close to these conditions.

The manufacturer guarantees the serviceability of transistors intended for linear amplification of a HF signal with a load mismatch of 30:1 for at least 1 s at rated power. This time is enough for the overload protection to trip. The operation of the power amplifier at such SWR values does not make sense, because. efficiency is practically "zero", i.e. I'm talking, of course, about emergencies.

To solve the problem of matching the transceiver equipment with antenna-feeder devices, there is a fairly cheap and simple way - the use of an additional external matching device. I would like to focus the attention of happy users of "bourgeois" equipment that does not have antenna tuners (and amateur designers too) on this very important issue.

All industrial transceiver equipment (including lamp equipment) is equipped with not only filtering, but also, additionally, matching units. Take, for example, tube radio stations R-140, R-118, R-130 - their matching devices occupy at least a quarter of the volume of the station. And all transistor broadband transmission equipment, without exception, is equipped with such matchers.

Manufacturers are even going to increase the cost of this equipment - they are equipped with automatic control systems (tuners). But this automation is designed to protect radio equipment from a stupid user who vaguely imagines what and why he should turn in the SU. It is assumed that a radio amateur with a call sign must have a minimal understanding of the processes occurring in the antenna-feeder device of his radio station.

Depending on which antennas are used at an amateur radio station, one or another matching device can be used. The claim by some shortwavers that they use an antenna whose SWR is close to unity on all bands, so no DC is required, shows a lack of minimal knowledge on the subject. No one has yet been able to deceive "physics" here - no high-quality resonant antenna will have the same resistance either within the entire range, and even more so on different ranges.

What happens most often - either "inverted-V" is installed on 80 and 40 m, or a frame with a perimeter of 80 m, and in the worst case, a clothesline is used as an "antenna". Especially "talented" invent universal pins and "carrots", which, according to the peremptory assurances of the authors, "work on all bands with virtually no tuning!"

Such a structure is tuned at best on one or two bands, and that's it - go ahead, "we call - they answer, what else is needed?" It is sad that in order to increase the "operational efficiency" of such antennas, all searches lead to "radio extenders" such as the output unit from the R-140 or R-118. It is enough to listen to those who like to "work in a group for a distance" at night on 160 and 80 meters, and recently this can already be seen on 40 and 20 meters.

If the antenna has SWR = 1 on all bands (or at least on several) - this is not an antenna, but active resistance, or the device that measures SWR "shows" the ambient temperature (which is usually constant in the room).

I don’t know whether or not I succeeded in convincing the reader that the use of SU is required, but, nevertheless, I will move on to describing the specific schemes of such devices. Their choice depends on the antennas used at the radio station. If the input impedances of the radiating systems do not fall below 50 ohms, you can get by with a primitive L-type matching device - Fig. 1, because it only works in the direction of increasing resistance. In order for the same device to "lower" the resistance, it must be turned on the other way around, i.e. Swap input and output.
Automatic antenna tuners of almost all imported transceivers are made according to the scheme shown in Fig. 2. Antenna tuners in the form of separate devices of the company are often manufactured according to a different scheme (Fig. 3). A description of this scheme can be found, for example, in . In all branded control systems manufactured according to this scheme, there is an additional frameless coil L2, wound with a wire with a diameter of 1.2 ... 1.5 mm on a mandrel with a diameter of 25 mm. Number of turns - 3, winding length - 38 mm.

Using the last two schemes, you can provide SWR \u003d 1 on almost any piece of wire. However, do not forget - SWR = 1 indicates that the transmitter has an optimal load, but this in no way means high antenna performance. With the help of the control system, the scheme of which is shown in Fig. 2, it is possible to match the probe from the tester as an antenna with SWR = 1, but, except for the nearest neighbors, no one will evaluate the efficiency of such an "antenna". A conventional P-loop can also be used as a control system - Fig. 4. The advantage of this solution is that it is not required to isolate the KPI from the common wire, the disadvantage is that with a large output power it is difficult to find variable capacitors with the required gap.

When using more or less tuned antennas at the station and in the case when it is not supposed to work at 160 m, the inductance of the CS coil may not exceed 10 ... 20 μH. It is very important that it is possible to obtain small inductances up to 1 ... 3 μH.

Ball variometers are usually not suitable for these purposes, because. the inductance is tuned to a lesser extent than that of coils with a "runner". In branded antenna tuners, coils with a "runner" are used, in which the first turns are wound with an increased pitch - this is done to obtain small inductances with a maximum quality factor and a minimum turn-to-turn connection.

Sufficiently high-quality coordination can be obtained by using a "poor ham radio variometer" in the control system. These are two coils connected in series with switching taps (Fig. 5). The coils are frameless, and contain 35 turns of wire with a diameter of 0.9 ... 1.2 mm (depending on the expected power), wound on a mandrel 020 mm.

After winding, the coils are rolled into a ring and soldered with taps to the terminals of conventional ceramic switches with 11 positions. Taps for one coil should be made from even turns, for the other - from odd ones, for example - from 1,3,5,7,9,11, 15,19, 23, 27th turns and from 2.4, 6, 8 ,10, 14,18,22,28,30th turns. By turning on two such coils in series, it is possible to select the required number of turns with switches, especially since the accuracy of inductance selection is not particularly important for the control system. With the main task - obtaining small inductances - the "poor radio amateur's variometer" copes successfully.

In order for this home-made tuner to approach “bourgeois” antenna tuners in terms of its quasi-smooth tuning capabilities, for example, AT-130 from ICOM or AT-50 from Kenwood, instead of one biscuit switch, shorting the coil taps with “relays” will have to be introduced, each of which will be switched on separately toggle switch. Seven "relays", switching seven taps, will be enough to simulate a "manual AT-50".

An example of relay switching of coils is given in. The gaps between the plates in the KPI must withstand the expected stress. If low-resistance loads are used, with an output power of up to 200 ... 300 W, KPI can be dispensed with from old types of RPU. If high-resistance, you will have to select a KPI with the required clearances (from industrial radio stations).
The approach when choosing a KPI is very simple - 1 mm of the gap between the plates withstands a voltage of 1000 V. The estimated voltage can be found by the formula U = C P / R, where:

P - power,

R is the load resistance.

A switch must be installed on the radio station, with which the transceiver is disconnected from the antenna in the event of a thunderstorm (or in the off state), because. more than 50% of transistor failures are due to static electricity. The switch can be mounted either in the antenna switch or in the SU.

U-shaped matching device

The result of various experiments and experiments on the topic discussed above was the implementation of a U-shaped "matcher" - Fig.6. Of course, it is difficult to get rid of the "bourgeois tuner circuit complex" in Fig. 2 - this circuit has an important advantage, which is that the antenna (at least the central core of the cable) is galvanically isolated from the transceiver input through the gaps between the KPE plates. But the unsuccessful search for suitable KPIs for this scheme forced it to be abandoned. By the way, the P-loop scheme is also used by some companies that produce automatic tuners, for example, the American CAT1 Elekraft or the Dutch Z-11 Zelfboum.

In addition to matching, the P-loop also acts as a low-pass filter, which is very useful when working on overloaded amateur radio bands - hardly anyone will refuse additional harmonic filtering. The main drawback of the U-shaped matching device circuit is the need to use KPI with a sufficiently large maximum capacitance, which suggests the reason why such a circuit is not used in automatic tuners of imported transceivers. In T-shaped schemes, two KPIs are most often used, rebuilt by motors. It is clear that a 300 pF KPI will be much smaller, cheaper and simpler than a 1000 pF KPI.

In the control system diagram shown in Fig. 6, KPIs with an air gap of 0.3 mm from tube receivers are used. Both sections of the capacitor are connected in parallel. As an inductance, a coil with taps switched by a ceramic biscuit switch is used.

The coil is frameless, and contains 35 turns of wire 00.9 ... 1.1 mm, wound on a mandrel 021 ... 22 mm. After winding, the coil is folded into a ring and soldered to the terminals of the biscuit switch with its short taps. The taps are made from the 2nd, 4th, 7th, 10th, 14th, 18th, 22nd, 26th and 31st turns.

The SWR meter is made on a ferrite ring. The permeability of the ring when working on KB, in general, is not of decisive importance; in the author's version, a 1000НН ring with an outer diameter of 10 mm was used.

The ring is wrapped with a thin varnished cloth, and then 14 turns of PEL 0.3 wire are wound on it (without twisting, in two wires). The beginning of one winding, connected to the end of the second, forms the middle output.

Depending on the required task (more precisely, on what power is supposed to pass through the control system, and on the quality of the VD4 and VD5 LEDs), silicon or germanium detection diodes VD2 and VD3 can be used. When using germanium diodes, a higher sensitivity can be obtained. The best of them are GD507. However, the author uses a transceiver with an output power of at least 50 W, so conventional KD522 silicon diodes work perfectly in the SWR meter.

As a "know-how", in addition to the usual, on the pointer device, LED indication of the setting is used. The green VD4 LED is used to indicate the "forward wave", and red (VD5) is used to visually control the "reverse wave". As practice has shown, this is a very good solution - you can always quickly respond to an emergency. If something happens to the load during on-air operation, the red LED starts flashing brightly in time with the emitted signal.

It is less convenient to navigate by the arrow of the SWR meter - you will not constantly stare at it during the transmission! But the bright glow of red light is clearly visible even with peripheral vision. This was positively appreciated by Yuri, RU6CK, when he got such an SU (besides, Yuri has poor eyesight). For more than a year now, the author himself has been using mainly only the "LED setting" of the control system, i.e. setting the "coordinator" is reduced to the fact that the red LED goes out and the green "blazes" brightly. If you really want a more precise setting, you can "catch" it along the arrow of the microammeter. An M68501 device with a total deflection current of 200 μA was used as a microammeter. M4762 can also be used - they were installed in the tape recorders "Nota", "Jupiter". It is clear that C1 must withstand the voltage output by the transceiver to the load.

The customization of the manufactured device is performed using a dummy load, which is designed to dissipate the output power of the cascade. We connect the SU to the transceiver with a "coax" of the minimum length (as far as possible, since this cable segment will be used in the further operation of the SU and the transceiver) with the required wave impedance, to the output of the SU without any "long cords" and coaxial cables we connect the equivalent load , unscrew all the SU knobs to a minimum and use C1 to set the minimum readings of the SWR meter during "reflection". It should be noted that the output signal of the transmitter must not contain harmonics (i.e. must be filtered), otherwise the minimum may not be found. If the design is made correctly, the minimum is obtained when the capacitance C1 is close to the minimum.

Then we swap the input and output of the device and check the "balance" again. Testing is carried out on several ranges. I warn you right away, the author is not able to help every radio amateur who has not coped with setting up the described control system. If someone is unable to make a control system on their own, you can order a finished product from the author of this article. All information can be found here.

LEDs VD4 and VD5 must be chosen modern, with maximum brightness. It is desirable that the LEDs have maximum resistance when the rated current flows. The author managed to purchase red LEDs with a resistance of 1.2 kOhm and green - 2 kOhm. Usually green LEDs glow weakly, but this is not bad - after all, not a Christmas tree garland is being made. The main requirement for a green LED is that its glow should be quite clearly visible in the normal transmission mode. But the color of the glow of the red LED, depending on the preferences of the user, you can choose from poisonous crimson to scarlet.

As a rule, such LEDs have a diameter of 3 ... 3.5 mm. For a brighter glow of the red LED, the voltage is doubled - a diode VD1 is introduced into the circuit. For this reason, our SWR meter can no longer be called an accurate measuring device - it overestimates the "reflection". If you want to measure accurate SWR values, you need to use LEDs with the same resistance and make the two arms of the SWR meter exactly the same - either both with or without doubling the voltage. However, the operator is more concerned with the quality of the match between the transceiver and the antenna than with the exact value of the SWR. For this, LEDs are enough.

The proposed control system is effective when working with antennas fed through a coaxial cable. The author tested the control system on "standard", common antennas of "lazy" radio amateurs - a "frame" with a perimeter of 80 m, "inverted-V" - combined 80 and 40 m, a "triangle" with a perimeter of 40 m, a "pyramid" for 80 m.

Konstantin, RN3ZF, (he has FT-840) uses such a control system with a "pin" and "inverted-V", including on the WARC bands, UR4GG - with a "triangle" at 80 m and transceivers "Volna" and " Danube", and UY5ID, using the described control system, coordinates the silo on KT956 with a multilateral frame with a perimeter of 80 m with symmetrical power supply (an additional transition to a symmetrical load is used).

If, when setting up the control system, it is not possible to turn off the red LED (reach the minimum readings of the device), this may mean that, in addition to the main signal, the emitted spectrum contains harmonics (the control system is not able to ensure coordination at several frequencies simultaneously). Harmonics, which are located above the main signal in frequency, do not pass through the low-pass filter formed by the SU elements, are reflected, and the red LED is “lit on fire” on the way back. The fact that the control system "does not cope" with the load can only be indicated by the fact that the matching occurs at extreme values (not minimum) of the KPI and coil parameters, i.e. when there is not enough capacitance or inductance. None of the indicated users, when operating the control system with the listed antennas, had such cases on any of the ranges.

SU was tested with a "rope", i.e. with a wire antenna 41 m long. It should not be forgotten that the SWR meter is a measuring instrument only if there is a load on both sides of it, at which it was balanced. When tuning to the "rope", both LEDs are lit, so the maximum brightness of the green LED with the minimum possible brightness of the red one can be taken as the tuning criterion. Apparently, this will be the most correct setting - for the maximum return of power to the load.

I would like to draw the attention of potential users of this control system to the fact that in no case should the coil taps be switched when the maximum power is emitted. At the moment of switching, the coil circuit breaks (albeit for a fraction of a second), and its inductance changes dramatically. Accordingly, the contacts of the biscuit switch burn out and the load resistance of the output stage changes dramatically. It is only necessary to switch the button switch in the receive mode.

Information for meticulous and "demanding" readers - the author of the article is aware that the SWR meter installed in the control system is not a precision high-precision measuring device. Yes, such a goal was not set in its manufacture! The main task was to provide the transceiver with broadband transistor cascades with an optimal matched load, I repeat once again - both for the transmitter and the receiver. The receiver, like a powerful silo, fully needs high-quality coordination with the antenna!

By the way, if in your "radio" the optimal settings for the receiver and transmitter do not match, this indicates that the device was not tuned or was not really done at all, and if it was done, then most likely only the transmitter, and the receiver's bandpass filters have optimal parameters at other load values.

The SWR meter installed in the SU will show that by adjusting the SU elements we have achieved the parameters of the load that was connected to the ANTENNA output of the transceiver during its tuning. Using SU, you can safely work on the air, knowing that the transceiver is not "puffing up and begging for mercy", but has almost the same load to which it was tuned. Of course, this does not mean that the antenna connected to the control system began to work better. Don't forget about it!

For radio amateurs who dream of a precision SWR meter, I can recommend making it according to the schemes given in many foreign serious publications, or buying a ready-made device. But you have to fork out - indeed, devices manufactured by well-known companies cost from 50 USD and more than SV - I don’t take into account the Polish-Turkish-Italian ones. A successful, well-described SWR meter design is given in.

A. Tarasov, (UT2FW) [email protected]

Literature:

Bunin S.G., Yaylenko L.P. Handbook of a radio amateur-shortwave. - K .: Technique, 1984.
M. Levit. A device for determining SWR. - Radio, 1978, N6.
http://www.cqham.ru/ut2fw/

The experience of numerous contacts and communication with users of transistor technology suggests that it is rare that a radio amateur who is not constantly engaged in design makes attempts to understand the issues of matching the transceiver with the load. Thoughts about coordination in such heads begin to arise only after an accident in the equipment. There is nothing to be done - the realities of today are as follows ... Examinations for obtaining categories have not yet become popular, at best - this is the delivery of the telegraph alphabet. Although for modern conditions, in my opinion, it is more expedient to check technical literacy - there would be less “group sex for long-distance work” and “arguing” about the advantages of UW3DI over “all sorts of Ikoms and Kenwoods” ... I would like to focus the attention of happy users of bourgeois equipment without antenna tuners, and amateur designers too, on this very important issue.

The choice depends on the antennas used at the station. If the input impedances of the radiating systems do not fall below 50 ohms, you can get by with a primitive L-type matching device, Fig.1

because it only works in the direction of increasing resistance. In order for the same device to "lower" the resistance, it will need to be turned on the other way around, swapping the input and output. Automatic antenna tuners of almost all imported transceivers are made according to the scheme Fig.2.

Antenna tuners in the form of separate devices of the company are often manufactured according to the scheme, Fig.3

Using the last two schemes, you can provide SWR \u003d 1 on almost any piece of wire. We must not forget that SWR=1 indicates that the transmitter has an optimal load, but this in no way characterizes the effective operation of the antenna. With the help of the control system according to the scheme of Fig. 2, it is possible to match the probe from the tester as an antenna with SWR = 1, but apart from the nearest neighbors, no one will evaluate the efficiency of such an "antenna". As a SU, you can use the usual P-loop, Fig.4

its advantage is that it is not necessary to isolate the capacitors from the case, the disadvantage is that at high output power it is difficult to find variable capacitors with the required clearance. For SU Fig.3 there is information in p.237. All branded control systems in this circuit have an additional L2 coil, it is frameless, wire with a diameter of 1.2-1.5 mm, 3 turns, a mandrel with a diameter of 25 mm, winding length 38 mm. When using more or less band antennas at the station and if it is not supposed to work at 160m, the coil inductance may not exceed 10-20 μH. The moment of obtaining inductances of small values, up to 1-3 μH, is very important. Ball variometers are usually not suitable for these purposes, because. the inductance is tuned to a lesser extent than that of coils with a "runner". In branded antenna tuners, coils with a "runner" are used, in which the first turns are wound with an increased pitch - this is done to obtain small inductances with a maximum quality factor and a minimum turn-to-turn connection. Sufficiently high-quality coordination can be obtained by using the "poor ham radio variometer". These are two coils connected in series with switching taps, Fig.5.

The coils are frameless, wound on a mandrel with a diameter of 20 mm, a wire with a diameter of 0.9-1.2 mm (depending on the expected power), 35 turns each. Then the coils are folded into a ring and soldered with their taps to the terminals of conventional 11-position ceramic switches. Taps for one coil should be made from even turns, for the other from odd ones, for example - from 1,3,5,7,9,11,15,19,23,27th turns and from 2,4,6,8, 10,14,18,22,28,30th turns. By turning on two such coils in series, it is possible to select the required number of turns with switches, especially since the accuracy of inductance selection is not particularly important for the control system. With the main task - obtaining small inductances, the "poor radio amateur's variometer" copes successfully. By the way, in the tuner of such an expensive TRX as the TS-940, only 7 taps are used, and in the automatic antenna tuners AT-130 from ICOM - 12 taps, AT-50 from Kenwood - 7 taps - so do not think that the option described here is “primitive which does not deserve your attention. In our case, we have an even "cooler" option - accordingly, a more precise setting - 20 taps. The gaps between the plates in the KPI must withstand the expected stress. If low-resistance loads are used, KPI can be dispensed with from old types of RPU, with an output power of up to 200-300W. If high-resistance, you will have to pick up KPI from radio stations with the required clearances. The calculation is simple - 1mm can withstand 1000V, the estimated voltage can be found from the formula P \u003d U` (squared) / R, where P is power, R is load resistance, U is voltage. Be sure to have a switch on the radio station, with which the transceiver is disconnected from the antenna in the event of a thunderstorm or inoperative condition, because. more than 50% of transistor failures are due to static electricity. It can be entered either in the antenna switching shield or in the SU.

Description of the matching device.

As a result of various experiences and experiments on this topic, the author was led to the scheme of a U-shaped "matcher".

Of course, it is difficult to get rid of the “bourgeois tuner circuit complex” (Fig. 2) - this circuit has an important advantage - the antenna (at least the central core of the cable) is galvanically isolated from the transceiver input through the gaps between the KPI plates. But the unsuccessful search for suitable KPIs for this scheme forced it to be abandoned. By the way, some companies that produce automatic tuners also use the P-loop scheme - the same American KAT1 Elekraft or the Dutch Z-11 Zelfboum. In addition to matching, the P-loop also performs the role of a low-pass filter, which is quite good for overloaded amateur radio bands; probably, it is unlikely that anyone will refuse additional filtering of unnecessary harmonics. The main drawback of the P-loop circuit is the need for a KPI with a sufficiently large maximum capacitance, which makes me wonder why such circuits are not used in automatic tuners of imported transceivers. In T-patterns, two motor-tunable KPIs are most often used and it is clear that a 300pF KPI will be much smaller, cheaper and simpler than a 1000pF KPI. In the SU, KPIs from lamp receivers with an air gap of 0.3 mm are used, both sections are connected in parallel. As an inductance, a coil with taps switched by a ceramic biscuit switch is used. A frameless coil of 35 turns of wire 0.9-1.1 mm is wound on a mandrel with a diameter of 21-22 mm, folded into a ring and soldered to the terminals of the biscuit switch with its short taps. The taps are made from 2,4,7,10,14,18,22, 26,31 turns. The SWR meter is made on a ferrite ring. For HF, the permeability of the ring is generally not of decisive importance - a K10 ring with a permeability of 1000 NN is used. It is wrapped with a thin varnished cloth and 14 turns are wound on it in two wires without twisting PEL 0.3, the beginning of one winding, connected to the end of the second, forms the middle output. Depending on the required task, more precisely, on what power is supposed to pass through this control system and the quality of the emitting LEDs, silicon or germanium detecting diodes D2, D3 can be used. From germanium diodes, you can get greater amplitudes and sensitivity. The best - GD507. But since the author uses a transceiver with an output power of at least 50W, ordinary silicon KD522 is enough. As a "know-how" in this control system, LED indication of the setting is used in addition to the usual one on the pointer device. The green LED AL1 is used to indicate the "forward wave", and the red LED AL2 is used to visually control the "reverse wave". As practice has shown, this solution is very successful - you can always quickly respond to an emergency - if something happens while working with a load, the red LED starts to flash brightly in time with the transmitter, which is not always so noticeable on the SWR meter. You won’t constantly stare at the SWR meter needle during the transmission, but the bright glow of red light is clearly visible even with peripheral vision. This was positively appreciated by RU6CK when he got such an SU (besides, Yuri has poor eyesight). For more than a year now, the author himself has been using mainly only the “LED setting” of the SU - i.e. the setting is to ensure that the red LED goes out and the green one blazes brightly. If you really want a more accurate setting, you can “catch” it by the arrow of the microammeter. The device is configured using the load dummy for which the output stage of the transmitter is designed. We connect the SU to the TRX of the minimum (as far as possible - since this piece will later be used to connect them) with a coaxial cable with the required characteristic impedance, to the output of the SU without any long laces and coaxial cables equivalent, we unscrew all the SU handles to a minimum and use C1 to set the minimum readings of the SWR meter with “reflection”. It should be noted that the output signal for tuning must not contain harmonics (ie must be filtered), otherwise there will be no minimum. If the design is done correctly, the minimum is obtained in the area of \u200b\u200bthe minimum capacity C1. We swap the input-output of the device and again check the “balance”. We check the setting on several ranges - if everything is OK, then the setting to the minimum will coincide in various positions. If it doesn’t match or doesn’t “balance” - look for a better “oil” in the inventor’s head ... I only tearfully ask - do not ask the author questions on how to make or set up such a control system - you can order a ready-made one if you can’t do it yourself. LEDs must be selected from modern ones with maximum brightness of the glow at maximum resistance. I managed to find red LEDs with a resistance of 1.2kOhm and green 2kOhm. Usually green ones glow weakly - but this is not bad - we do not make a Christmas tree garland. The main task is to make it glow quite clearly in the normal mode for the transmission of the transceiver. But red, depending on the goals and preferences of the user, you can choose from poisonous raspberry to scarlet. As a rule, these are LEDs with a diameter of 3-3.5 mm. For a brighter red glow, a doubling of the voltage is applied - a diode D1 is introduced. Because of this, our SWR meter can no longer be called an accurate measuring device - it overestimates the “reflection” and if you want to calculate the exact value of the SWR, you will have to take this into account. If there is a need to precisely measure the exact values of SWR - you need to use LEDs with the same resistance and make the two arms of the SWR meter exactly the same - either with doubling the voltage, both or both without it. Only in this case will we obtain the same value of stresses coming from the arms Tr to MA. But rather, we are more concerned not with what kind of SWR we have, but with the fact that the TRX antenna circuit is consistent. For this, the indications of the LEDs are quite enough. This SU is effective when used with unbalanced antennas fed through a coaxial cable. The author carried out tests on "standard" common antennas of "lazy" radio amateurs - a frame with a perimeter of 80m, Inverted-V combined 80 and 40m, a triangle with a perimeter of 40m, a pyramid at 80m. Konstantin RN3ZF uses such a control system with a pin, Inverted-V, including on WARC bands, he has an FT-840. UR4GG is used with 80m triangle and Volna and Danube transceivers. UY5ID coordinates the silo on KT956 with a multi-sided frame with a perimeter of 80 m with symmetrical power, uses an additional "transition" to a symmetrical load. If during tuning it is not possible to turn off the red LED (to achieve the minimum readings of the device), this may indicate that, in addition to the main signal, there are more components in the emitted spectrum and the control system is not able to skip them and coordinate them simultaneously at all emitted frequencies. And those harmonics that lie above the main signal in frequency do not pass through the low-pass filter, formed by the SU elements, are reflected and the red LED is “lit on fire” on the way back. The fact that the control system does not “cope” with the load can only be indicated by the fact that the matching occurs at extreme values (not minimum) of the KPI and coil parameters - i.e. not enough capacitance or inductance. None of the users on the listed antennas on any of the ranges of such cases was noted. The use of a control system with a "rope" - a wire 41 m long was tested. It should not be forgotten that the SWR meter is a measuring instrument only if there is a load on both sides of it at which it is balanced. When tuned to the “rope”, both LEDs are lit, and as a reference point, you can take the brightest green glow with the lowest possible red. It can be assumed that this will be the most correct setting - for maximum return to the load. I would also like to note that in no case should the coil taps be switched when the maximum power is emitted. At the moment of switching, the circuit breaks (albeit for a fraction of a second) - the inductance changes sharply - accordingly, the contacts of the biscuit switch burn out and the load on the transceiver changes dramatically. Switching the hard switch must be done when the transceiver is set to RX. An M68501 device with a total deflection current of 200 μA was used as a microammeter. M4762 can also be used - they were used in tape recorders "Nota", "Jupiter". It is clear that C1 must withstand the voltage output by the transceiver in the load. Information for meticulous and "demanding" readers - the author is aware that this type of SWR meter is not a precision high-precision measuring instrument. But the manufacture of such a device was not set. The main task was to provide the transceiver with broadband transistor cascades with an optimal matched load, I repeat once again - both for the transmitter and the receiver. The receiver in the same full extent needs high-quality coordination with the antenna, as well as a powerful silo! By the way, if in your “radiv” the optimal settings for the receiver and transmitter do not match, this indicates that the setting was either not really done at all, and if it was done, then most likely only the transmitter and the receiver’s bandpass filters have optimal parameters for other load values than it was debugged on the transmitter. The task of our SWR meter is to show that by twisting the SU knobs we have achieved those load parameters that were connected to the ANTENNA output during tuning. And we can safely work on the air, knowing that now the transceiver is not “puffing up and begging for mercy”, but has almost the same load to which it was tuned. This, of course, does not mean that your antenna began to work better from this SU, do not forget about it! For those who suffer from a precision SWR meter, I can recommend making it according to the schemes given in many serious foreign publications or buying a ready-made device. But you have to fork out - indeed, devices from well-known companies cost from $ 50 and more, I do not take into account the SV-ish Polish-Turkish-Italian ones.

In amateur practice, it is not so common to find antennas in which the input impedance is equal to the feeder, as well as the output impedance of the transmitter. In the vast majority of cases, such a match cannot be detected, so specialized matching devices must be used. Antenna, feeder, as well as the output of the transmitter are included in a single system in which energy is transmitted without any loss.

How to do it?

To accomplish this rather complicated task, it is necessary to use matching devices in two main places - this is the point where the antenna connects to the feeder, and also the point where the feeder connects to the transmitter output. The most widespread today are specialized transforming devices, ranging from oscillatory resonant circuits to coaxial transformers, made in the form of separate pieces of a coaxial cable of the required length. All of these matchers are used to match impedances, ultimately minimizing overall transmission line loss and, more importantly, reducing out-of-band emissions.

Resistance and its features

In the vast majority of cases, the standard output impedance in modern broadband transmitters is 500 m. It is worth noting that many coaxial cables used as a feeder also differ in the standard impedance of 50 or 750 m. If we consider antennas for which matching devices can be used, then, depending on the design and type, the input impedance in them has a fairly wide range of values, ranging from a few ohms to hundreds and even more.

It is known that in single-element antennas, the input impedance at the resonant frequency is practically active, and the more the transmitter frequency differs from the resonant one in one direction or another, the more the reactive component of an inductive or capacitive nature will appear in the input impedance of the device itself. At the same time, multi-element antennas have an input impedance at the resonant frequency, which has a complex character due to the fact that various passive elements contribute to the formation of the reactive component.

If the input impedance is active, it can be matched to the impedance using a specialized antenna matching device. It should be noted that the losses here are practically negligible. However, as soon as a reactive component begins to form in the input impedance, the matching procedure will become more and more complex, and an increasingly complex antenna matching device will need to be used, the capabilities of which will compensate for unwanted reactivity, and it should be located directly at the point nutrition. If reactivity is not compensated for, this will adversely affect the SWR in the feeder and will also significantly increase the overall losses.

Does it need to be done?

An attempt to fully compensate for reactivity at the lower end of the feeder is unsuccessful, since it is limited by the characteristics of the device itself. Any changes in the frequency of the transmitter within the narrow sections of the amateur bands will ultimately not lead to the appearance of a significant reactive component, as a result of which there is often no need to compensate for it. It is also worth noting that the correct design of multi-element antennas also does not provide for a large reactive component of the available input impedance, which does not require its compensation.

On the air, you can often find various disputes about the role and purpose of the matching device for the antenna (“long wire” or another type) in the process of matching the transmitter with it. Some have rather high hopes for it, while others simply consider it an ordinary toy. That is why you need to correctly understand how an antenna tuner can really help in practice, and where its use will be superfluous.

What it is?

First of all, you need to correctly understand that the tuner is a high-frequency resistance transformer, with the help of which, if necessary, it will be possible to compensate for reactivity of an inductive or capacitive nature. Consider a very simple example:

A split vibrator, which at the resonant frequency has an active input impedance of 700 m, and at the same time it is used with a transmitter, having an input impedance of about 500 m. Tuners are installed at the output of the transmitter, and in this situation they will be for any antenna (including the "long cable") matching devices between the transmitter and the feeder, without any difficulties coping with their main task.

If in the future the transmitter is tuned to a frequency that differs from the resonant frequency of the antenna, then in this case, reactivity may appear in the input resistance of the device, which subsequently almost immediately begins to appear at the lower end of the feeder. In this case, the matching device "P" of any series will also be able to compensate for it, and the transmitter will again receive consistency with the feeder.

What will be at the output where the feeder connects to the antenna?

If you use the tuner exclusively at the output of the transmitter, then in this case it will not be possible to provide full compensation, and various losses will begin to occur in the device, since there will be incomplete matching. In such a situation, it will be necessary to use another one connecting between the antenna and the feeder, which will completely correct the situation and provide reactivity compensation. In this example, the feeder acts as a matched transmission line having an arbitrary length.

One more example

The loop antenna, which has an active input impedance of about 1100 m, must be matched to the transmission line at 50 ohms. The transmitter output in this case is 500 m.

Here you will need to use a matching device for the transceiver or antenna, which will be installed at the point where the feeder is connected to the antenna. In the vast majority of cases, many hobbyists prefer to use various types of RF transformers equipped with ferrite cores, but in fact, a quarter-wave coaxial transformer, which can be made from a standard 75-ohm cable, is a more convenient solution.

How to implement it?

The length of the cable section used should be calculated using the formula A / 4 * 0.66, where A is the wavelength, and 0.66 is the velocity factor used for the vast majority of modern coaxial cables. The HF antenna matching devices in this case will be connected between the 50-ohm feeder and the antenna input, and if they are rolled into a bay with a diameter of 15 to 20 cm, then in this case it will also act as a balancing device. The feeder will be fully automatically coordinated with the transmitter, as well as if their resistances are equal, and in such a situation it will be possible to completely abandon the services of a standard antenna tuner.

Another variant

For such an example, we can consider another optimal matching method - using a multiple of half a wave or a half-wave coaxial cable, in principle, with any wave impedance. It is included between the tuner located near the transmitter and the antenna. In this case, the input impedance of the antenna, which has a value of 110 ohms, is transferred to the lower end of the cable, after which, using an antenna matching device, it is transformed into a resistance of 500 m. In this case, full matching of the transmitter with the antenna is provided, and the feeder is used as a repeater .

In more severe situations, when the input impedance of the antenna is inappropriate for the wave impedance of the feeder, which, in turn, does not correspond to the output impedance of the transmitter, two HF antenna matching devices are required. In this case, one is used at the top to match the feeder to the antenna, while the other is used to match the feeder to the transmitter at the bottom. At the same time, there is no way to make some matching device with your own hands, which can be used alone to match the entire circuit.

The emergence of reactivity will make the situation even more complicated. In this case, HF band matching devices will significantly improve the matching of the transmitter with the feeder, thus providing a significant simplification of the operation of the final stage, but you should not expect more from them. Due to the fact that the feeder will be mismatched with the antenna, losses will appear, so the efficiency of the device itself will be underestimated. An activated SWR meter installed between the tuner and the transmitter will ensure that the SWR = 1 is fixed, and this effect cannot be achieved between the feeder and the tuner, since there is a mismatch.

Output

The benefit of the tuner is that it allows you to maintain the optimal mode of the transmitter in the process of working on an inconsistent load. But at the same time, an improvement in the efficiency of any antenna (including the “long wire”) cannot be ensured - the matching devices are powerless if it is mismatched with the feeder.

The P-loop, which is used in the output stage of the transmitter, can also be used as an antenna tuner, but only if there is an operational change in the inductance and each capacitance. In the vast majority of cases, both manual and automatic tuners are resonant contour tunable devices, regardless of whether they are assembled at the factory or someone decided to make a matching device for the antenna with their own hands. There are two or three regulating elements in manual ones, and they themselves are not operational in operation, while automatic ones are expensive, and for work at serious powers, their cost can be extremely high.

Broadband matching device

Such a tuner satisfies the predominant majority of variations in which it is necessary to ensure the matching of the antenna with the transmitter. Such equipment is quite effective in the process of working with antennas used on harmonics, if the feeder is a half-wave repeater. In this situation, the input impedance of the antenna is different on different bands, but the tuner allows for easy matching with the transmitter. The proposed device can easily operate at transmitter powers up to 1.5 kW in the frequency band from 1.5 to 30 MHz. Such a device can be made even with your own hands.

The main elements of the tuner are an RF autotransformer on the UNT-35 TV from the deflecting system, as well as a switch designed for 17 positions. It is possible to use cone rings from models UNT-47/59 or any other. There are 12 turns in the winding, which are wound into two wires, while the beginning of one is combined with the end of the second. In the diagram and in the table, the numbering of the turns is through, while the wire itself is stranded and enclosed in fluoroplastic insulation. In terms of insulation, the wire diameter is 2.5 mm, providing taps from each turn, starting from the eighth, if counting from the grounded end.

The autotransformer is installed as close as possible to the switch, while the connecting conductors between them must have a minimum length. It is possible to use a switch with 11 positions if the design of the transformer with a not so large number of taps is saved, for example, from 10 to 20 turns, but in this situation the resistance transformation interval will also decrease.

Knowing the exact value of the input impedance of the antenna, such a transformer can be used to match the antenna to a 50 or 750 m feeder, using only the most necessary taps. In such a situation, it is placed in a special moisture-proof box, after which it is filled with paraffin and placed directly at the feed point of the antenna. By itself, the matching device can be performed as an independent design or included in a special antenna-switching unit of some radio station.

For clarity, the label mounted on the switch handle shows the amount of resistance that corresponds to this position. To ensure full compensation of the reactive inductive component, it is possible to subsequently connect a variable capacitor.

The table below clearly indicates how the resistance depends on the number of turns you have made. In this case, the calculation was carried out based on the ratio of resistances, which is in quadratic dependence on the total number of turns made.

Description of the matching device

As a result of various experiments and experiments on this topic, the author led the author to the scheme of a U-shaped "matcher". By the way, some companies that produce automatic tuners also use the P-loop scheme - the same American KAT1 Elekraft or the Dutch Z-11 Zelfboum. In addition to matching, the P-loop also performs the role of a low-pass filter (by the way, this is what we need!), Which is quite good for overloaded amateur radio bands, probably, hardly anyone will refuse additional filtering of unnecessary harmonics.

The main drawback of the P-loop circuit is the need for a KPI with a sufficiently large maximum capacitance, which makes me wonder why such schemes are not used in automatic tuners of imported transceivers - just take a look at the cost of KPIs with small and large capacitance. In T-patterns, two motor-tunable KPIs are most often used, and it is clear that 300pF KPIs (which are required for a T-pattern) will be much smaller, cheaper and simpler than 1000-2000pF KPIs.

In our control system, KPIs from lamp receivers with an air gap of 0.3 mm are used, both sections are connected in parallel. As an inductance, a coil with taps switched by a ceramic biscuit switch is used. A frameless coil of 35 turns of wire 0.9-1.1 mm is wound on a mandrel with a diameter of 21-22 mm, folded into a ring and soldered to the terminals of the biscuit switch with its short taps. The taps are made from 2,4,7,10,14,18,22, 26,31 turns. The SWR meter is made on a ferrite ring. For HF, the permeability of the ring is generally not of decisive importance - a K10 ring with a permeability of 1000 NN is used. and 14 turns are wound on it in two wires without twisting PEL 0.3, the beginning of one winding, connected to the end of the second, forms the middle output. Depending on the required task, more precisely, on how much power is supposed to be passed through this control system and the quality of the emitting LEDs, silicon or germanium detecting diodes D2, D3 can be used.

From germanium diodes, you can get greater amplitudes and sensitivity. The best - GD507. But since the author uses a transceiver with an output power of at least 50W, ordinary silicon KD522 is enough. As a "know-how" in this control system, LED indication of the setting is used in addition to the usual one on the pointer device. The green (blue) LED AL1 is used to indicate the "forward wave", and the red LED AL2 is used to visually control the "reverse wave". As practice has shown, this solution is very successful - you can always quickly respond to an emergency - if something happens while working with a load, the red LED starts to flash brightly in time with the transmitter, which is not always so noticeable on the SWR meter. You won’t constantly stare at the SWR meter needle during the transmission, but the bright glow of red light is clearly visible even with peripheral vision. This was positively appreciated by RU6CK when he got such an SU (Yuri has a vision problem). For a sufficient number of years, and the author himself uses mainly only the "LED setting" of the SU - i.e. the setting is to ensure that the red LED goes out and the green one blazes brightly.

If you really want a more precise setting, then you can “catch” it by the arrow of the microammeter. The device is tuned using a 50Ω dummy load, which is designed for the transmitter output stage. We connect the SU to the TRX of the minimum (as far as possible - since this piece will be used to connect them in the future) with a coaxial cable with the required characteristic impedance, to the output of the SU without any long laces and coaxial cables equivalent to the load, we unscrew all the SU handles on minimum and set using C1 the minimum reading of the SWR meter with "reflection".

I note that C6 plates need to be introduced a little and the capacitance of C6 will depend on the length of the coax from TRX to SU and the workmanship of all "wiring" in the SU itself, i.e. With the capacitance C6, we compensate for the reactivity introduced by the coax and wiring in the SU. It is necessary to balance the SWR meter several times with capacitor C1 at the lowest possible capacitance C6. It should be noted that the output signal for tuning should not contain harmonics (i.e., it should be filtered), otherwise there will be no minimum. If the design is done correctly, the minimum is obtained in the area of \u200b\u200bthe minimum capacity of C1 and C6. We swap the input-output of the device and check the "balance" again. We check the setting on several ranges - if everything is OK, then the setting to the minimum will coincide in various positions.

If it doesn’t match or doesn’t “balance” - look for a better “oil” in the inventor’s head ... J I only tearfully ask - do not ask the author questions on how to make or set up such a control system - you can order a ready-made one if you can’t do it yourself. LEDs must be selected from modern ones with maximum brightness of the glow at maximum resistance. I managed to find red LEDs with a resistance of 1.2kOhm and green 2kOhm. The main task is to make it glow quite clearly in the normal mode for the transmission of the transceiver. But red, depending on the goals and preferences of the user, you can choose from poisonous raspberry to scarlet. As a rule, these are LEDs with a diameter of 3-3.5 mm. For a brighter red glow, a doubling of the voltage is applied - a diode D1 is introduced. Because of this, our SWR meter can no longer be called an accurate measuring device - it overestimates the "reflection" and if you want to calculate the exact SWR value, you will have to take this into account. If there is a need to measure exact SWR values, you need to use LEDs with the same resistance and make the two arms of the SWR meter exactly the same - either with doubling the voltage, both or both without it. Only in this case will we obtain the same value of stresses coming from the arms Tr to MA. But rather, we are more concerned not with what kind of SWR we have, but with the fact that the TRX antenna circuit is consistent. For this, the indications of the LEDs are quite enough. This SU is effective when used with unbalanced antennas fed through a coaxial cable. The author carried out tests on "standard" widespread antennas of "poor" radio amateurs - a frame with a perimeter of 80m, Inverted-V combined 80 and 40m, a triangle with a perimeter of 40m, a pyramid at 80m.

Konstantin RN3ZF uses such a control system with a pin, Inverted-V, including on WARC bands, he has an FT-840. UR4GG is used with 80m triangle and "Volna" and "Danube" transceivers. UY5ID coordinates the silo on KT956 with a multi-sided frame with a perimeter of 80 m with symmetrical power, uses an additional "transition" to a symmetrical load. If during tuning it is not possible to turn off the red LED, this may indicate that, in addition to the main signal, there are still components in the emitted spectrum and the control system is not able to skip them and coordinate them simultaneously at all emitted frequencies. And those harmonics that lie above the main signal in frequency do not pass through the low-pass filter, which is formed by the control system elements, are reflected and the red LED is “lit on fire” on the way back. The fact that the CS does not "cope" with the load can only be indicated by the fact that the matching occurs at extreme values (not minimum) of the KPI and coil parameters - i.e. not enough capacitance or inductance. None of the users on the listed antennas on any of the ranges of such cases was noted.

The use of a control system with a "rope" - a wire 41 m long was tested. It should not be forgotten that the SWR meter is a measuring instrument only if there is a load on both sides of it at which it is balanced. When tuned to the "rope", both LEDs are lit, and as a reference point, you can take the brightest glow of green (blue), with the minimum possible red. It can be assumed that this will be the most correct setting - for maximum return to the load. If you are constantly working for the "rope", then remember that for its effective operation, you should create a second "pole", i.e. EARTH! As a last resort, a heating battery can serve as the ground, at best - a tuned counterweight. When you connect the second "pole" to the control system - the ground - then the readings of the LEDs and the device will become more "meaningful".

I would also like to note that in no case should the coil taps be switched when the maximum power is emitted. At the moment of switching, the circuit breaks (albeit for a fraction of a second) - the inductance changes sharply - accordingly, the contacts of the biscuit switch burn out and the load on the transceiver changes dramatically. Switching the hard switch should only be done when the transceiver is set to RX. A device with a total deflection current of 200 μA was used as a microammeter. It is clear that C1 must withstand the voltage output by the transceiver in the load.

Information for meticulous and "demanding" readers - the author is aware that this type of SWR meter is not a precision high-precision measuring instrument. But, the task of manufacturing such a device was not set! The main task was to provide the transceiver with broadband transistor cascades with an optimal matched load, I repeat once again, both for the transmitter and the receiver. The receiver in the same full extent needs high-quality coordination with the antenna, as well as a powerful silo! By the way, if in your "radiva" the optimal settings for the receiver and transmitter do not match, this indicates that the transceiver was not tuned or was not really done at all, and if it was done, then most likely only the transmitter. And the bandpass filters of the receiver have optimal parameters for other load values than it was debugged on the transmitter.

The task of our SWR meter is to show that by turning the SU knobs we have achieved the parameters of the load that we connected to the ANTENNA output during tuning. And we can safely work on the air, knowing that now the transceiver is not "puffing up and begging for mercy", but has almost the same load to which it was tuned. This, of course, does not mean that your antenna began to work better from the use of this SU, do not forget about it! For those who suffer from a precision SWR meter, I can recommend making it according to the schemes given in many serious foreign publications or buying a ready-made device. But you have to fork out - indeed, only SWR meters (!) From well-known companies cost from $ 50 and more, I don’t take into account SW-ish Polish-Turkish-Italian ones.

A good and complete article on the manufacture of an SWR meter was in the Radio magazine No. 6 1978, by M. Levit (UA3DB). If it seems that one of the LEDs AL1 or AL2 "shines in the eye" too brightly, you need to enter in series with it and select a current-limiting resistor according to the brightness of the glow. Only, after this change in the scheme, it will be necessary to re-check the setting of the control system. Because The arms of the SWR meter are loaded mainly with the resistance of the LEDs, and with their change, the balance of the SWR meter is likely to be disturbed.

The choice depends on the antennas used at the station. If the input impedances of the radiating systems do not fall below 50 ohms, you can get by with a primitive L-type matching device, Fig.1

Antenna tuners in the form of separate devices of the company are often manufactured according to the scheme, Fig.3

Description of the matching device.

As a result of various experiences and experiments on this topic, the author was led to the scheme of a U-shaped "matcher".

A.Tarasov UT2FW