Antenna matching devices. Tuners
ACS. Antenna tuners. Scheme. Reviews of branded tuners
In amateur radio practice, it is not so often possible to find antennas in which the input impedance is equal to the characteristic impedance of the feeder, as well as the output impedance of the transmitter.
In the vast majority of cases, such a correspondence cannot be detected, so it is necessary to use specialized antenna matching devices. The antenna, feeder and transmitter output (transceiver) are part of a single system in which energy is transmitted without any loss.
Do you need an antenna tuner?
From Alexey RN6LLV:
In this video I will tell novice radio amateurs about antenna tuners.
Why do you need an antenna tuner, how to use it correctly in conjunction with an antenna, and what are the typical misconceptions about the use of a tuner among radio amateurs.
We are talking about a finished product - a tuner (produced by the company), if you want to build your own, save money or experiment, then you can skip the video and see further (below).
Just below are reviews of branded tuners.
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All-range matching device (with separate coils)
Variable capacitors and biscuit switch from R-104 (BSN unit).
In the absence of the specified capacitors, you can use 2-section ones from broadcast radio receivers, connecting the sections in series and isolating the body and axis of the capacitor from the chassis.
You can also use a regular biscuit switch, replacing the rotation axis with a dielectric one (fiberglass).
Details of tuner coils and components:
L-1 2.5 turns, AgCu wire 2 mm, coil outer diameter 18 mm.
L-2 4.5 turns, AgCu wire 2 mm, outer diameter of the coil 18 mm.
L-3 3.5 turns, AgCu wire 2 mm, outer diameter of the coil 18 mm.
L-4 4.5 turns, AgCu wire 2 mm, outer diameter of the coil 18 mm.
L-5 3.5 turns, AgCu wire 2 mm, outer diameter of the coil 18 mm.
L-6 4.5 turns, AgCu wire 2 mm, outer diameter of the coil 18 mm.
L-7 5.5 turns, PEV wire 2.2 mm, outer diameter of the coil 30 mm.
L-8 8.5 turns, PEV wire 2.2 mm, outer diameter of the coil 30 mm.
L-9 14.5 turns, PEV wire 2.2 mm, outer diameter of the coil 30 mm.
L-10 14.5 turns, PEV wire 2.2 mm, outer diameter of the coil 30 mm.
Source: http://ra1ohx.ru/publ/skhemia_radioljubitelju/soglasujushhie_ustrojstva_antennye_tjunery/vsediapazonnoe_su_s_razdelnymi_katushkami/19-1-0-652
Simple matching of LW antenna - "long wire"
It was urgent to launch 80 and 40 m in someone else's house, there was no access to the roof, and there was no time to install an antenna.
I threw a vole a little over 30 m from the third floor balcony onto a tree. I took a piece of plastic pipe with a diameter of about 5 cm and wound about 80 turns of wire with a diameter of 1 mm. I made taps at the bottom every 5 turns, and at the top every 10 turns. I assembled this simple matching device on the balcony.
I hung a field strength indicator on the wall. I turned on the 80 m range in QRP mode, picked up a tap on top of the coil and used a capacitor to tune my “antenna” to resonance according to the maximum indicator readings, then picked up a tap at the bottom to the minimum of the VAC.
There was no time, and therefore I didn’t put up biscuits. and “ran” along the turns with the help of crocodiles. And the entire European part of Russia responded to such a surrogate, especially at 40 m. No one even paid attention to my vole. This is of course not a real antenna, but the information will be useful.
RW4CJH info - qrz.ru
Matching device for low frequency range antennas
Radio amateurs living in multi-storey buildings often use loop antennas on the low frequency bands.
Such antennas do not require high masts (they can be stretched between houses at a relatively high altitude), good grounding, a cable can be used to power them, and they are less susceptible to interference.
In practice, a triangle-shaped frame is convenient, since its suspension requires a minimum number of attachment points.
As a rule, most shortwave operators tend to use such antennas as multi-band antennas, but in this case it is extremely difficult to ensure acceptable matching of the antenna with the feeder on all operating bands.
For more than 10 years I have been using a Delta antenna on all bands from 3.5 to 28 MHz. Its features are its location in space and the use of a matching device.
Two vertices of the antenna are fixed at the roof level of five-story buildings, the third (open) is on the balcony of the 3rd floor, both of its wires are inserted into the apartment and connected to a matching device, which is connected to the transmitter with a cable of arbitrary length.
At the same time, the perimeter of the antenna frame is about 84 meters.
The schematic diagram of the matching device is shown in the figure on the right.
The matching device consists of a broadband balun transformer T1 and a P-circuit formed by a coil L1 with taps and capacitors connected to it.
One of the options for transformer T1 is shown in Fig. left.
Details. Transformer T1 is wound on a ferrite ring with a diameter of at least 30 mm with a magnetic permeability of 50-200 (non-critical). The winding is carried out simultaneously with two PEV-2 wires with a diameter of 0.8 - 1.0 mm, the number of turns is 15 - 20.
The P-circuit coil with a diameter of 40...45 mm and a length of 70 mm is made of bare or enameled copper wire with a diameter of 2-2.5 mm. Number of turns 13, bends from 2; 2.5; 3; 6 turns, counting from the left according to the L1 output circuit. Trimmed capacitors of the KPK-1 type are assembled on studs in packages of 6 pieces. and have a capacitance of 8 - 30 pF.
Setup. To configure the matching device, you need to connect the SWR meter to the cable break. On each band, the matching device is adjusted to a minimum SWR using adjusted capacitors and, if necessary, selecting the position of the tap.
Before setting up the matching device, I advise you to disconnect the cable from it and set up the output stage of the transmitter by connecting an equivalent load to it. After this, you can restore the connection between the cable and the matching device and perform final adjustments to the antenna. It is advisable to split the 80-meter range into two sub-bands (CW and SSB). When tuning, it is easy to achieve an SWR close to 1 on all ranges.
This system can also be used on the WARC bands (you just need to select the taps) and on 160 m, accordingly increasing the number of coil turns and the perimeter of the antenna.
It should be noted that all of the above is true only when the antenna is directly connected to the matching device. Of course, this design will not replace the “wave channel” or “double square” at 14 - 28 MHz, but it is well tuned on all bands and removes many problems for those who are forced to use one multi-band antenna.
Instead of switchable capacitors, you can use KPE, but then you will have to tune the antenna every time you switch to another band. But, if this option is inconvenient at home, then in field or hiking conditions it is completely justified. I have repeatedly used reduced versions of “delta” for 7 and 14 MHz when working in the “field”. In this case, two peaks were attached to trees, and the supply was connected to a matching device lying directly on the ground.
In conclusion, I can say that using only a transceiver with an output power of about 120 W for operation on the air without any power amplifiers, with the described antenna on bands 3.5; 7 and 14 MHz have never experienced any difficulties, while I usually work on a general call.
S. Smirnov, (EW7SF)
Design of a simple antenna tuner
Antenna tuner design from RZ3GI
I offer a simple version of an antenna tuner assembled in a T-shape.
Tested together with FT-897D and IV antenna at 80, 40 m.
Built on all HF bands.
Coil L1 is wound on a 40 mm mandrel with a pitch of 2 mm and has 35 turns, a wire with a diameter of 1.2 - 1.5 mm, taps (counting from the ground) - 12, 15, 18, 21, 24, 27, 29, 31, 33, 35 turns.
Coil L2 has 3 turns on a 25 mm mandrel, winding length 25 mm.
Capacitors C1, C2 with C max = 160 pf (from the former VHF station).
The built-in SWR meter is used (in FT - 897D)
Inverted Vee antenna for 80 and 40 meters - built on all bands.
Yuri Ziborov RZ3GI.
Tuner photo:
"Z-match" antenna tuner
A great many designs and schemes are known under the name “Z-match”, I would even say more designs than schemes.
The basis of the circuit design from which I based is widely distributed on the Internet and offline literature, it all looks something like this (see right):
And so, considering the many various schemes, photographs and notes posted on the Internet, I came up with the idea of building an antenna tuner for myself.
My hardware magazine was at hand (yes, yes, I am a follower of the old school - old school, as young people say) and on its page a diagram of a new device for my radio station was born.
I had to remove a page from the magazine “to get to the point”:
It is noticeable that there are significant differences from the original source. I did not use inductive coupling with the antenna with its symmetry; for me, an autotransformer circuit is enough because There are no plans to power the antennas with a balanced line. For ease of setup and control of antenna-feeder structures, I added general scheme SWR meter and Wattmeter.
Having finished calculating the circuit elements, you can begin prototyping:
In addition to the housing, it is necessary to manufacture some radio elements; one of the few radio components that a radio amateur can make himself is an inductor:
And here is what happened as a result, inside and outside:
The scales and markings have not yet been applied, the front panel is faceless and not informative, but the main thing is that it WORKS!! And this is good…
R3MAV. info - r3mav.ru
Matching device similar to Alinco EDX-1
I borrowed this antenna matching device circuit from the branded Alinco EDX-1 HF ANTENNA TUNER, which worked with my DX-70.
Details:
C1 and C2 300 pf. Air dielectric capacitors. Plate pitch 3 mm. Rotor 20 plates. Stator 19. But you can use dual KPIs with a plastic dielectric from old transistor receivers or with an air dielectric 2x12-495 pf. (as in the picture)
You ask: “Won’t it sew?” The fact is that the coaxial cable is soldered directly to the stator, and this is 50 Ohms, and where should the spark jump with such a low resistance?
It is enough to stretch a line 7-10 cm long from the capacitor with a “bare” wire, and it will burn with a blue flame. To remove static, the capacitors can be bypassed with a 15 kOhm 2 W resistor (quote from “Power amplifiers of the UA3AIC design”).
L1 - 20 turns of silver-plated wire D=2.0 mm, frameless D=20 mm. Bends, counting from the top end according to the diagram:
L2 25 turns, PEL 1.0, wound on two ferrite rings folded together, dimensions D outer = 32 mm, D int = 20 mm.
Thickness of one ring = 6 mm.
(For 3.5 MHz).
L3 has 28 turns, and everything else is the same as L2 (For 1.8 MHz).
But, unfortunately, at that time I could not find suitable rings and did this: I cut rings out of plexiglass and wound wires around them until they were filled. I connected them in series - it turned out to be the equivalent of L2.
On a mandrel with a diameter of 18 mm (you can use a plastic sleeve from a 12-gauge hunting rifle), 36 turns were wound turn to turn - this turned out to be an analogue of L3.
Everything is visible in the photo. And the SWR meter too. SWR meter from the description of Tarasov A. UT2FW “HF-VHF” No. 5 for 2003.
Matching device for delta, square, trapezoid antennas
Among radio amateurs, a loop antenna with a perimeter of 84 m is very popular. It is mainly tuned to the 80M band and with a slight compromise it can be used on all amateur radio bands. This compromise can be accepted if we are working with a tube power amplifier, but if we have a more modern transceiver, things will no longer work there. A matching device is needed that sets the SWR on each band, corresponding to the normal operation of the transceiver. HA5AG told me about a simple matching device and sent me a short description of it (see picture). The device is designed for loop antennas of almost any shape (delta, square, trapezoid, etc.)
Short description:
The author tested the matching device on an antenna, the shape of which is almost square, installed at a height of 13 m in a horizontal position. The input impedance of this QUAD antenna on the 80 m band is 85 Ohms, and on harmonics it is 150 - 180 Ohms. The characteristic impedance of the supply cable is 50 Ohms. The task was to match this cable with the antenna input impedance of 85 - 180 Ohms. For matching, transformer Tr1 and coil L1 were used.
In the range of 80 m, using relay P1, we short-circuit coil n3. In the cable circuit, coil n2 remains switched on, which, with its inductance, sets the input impedance of the antenna to 50 Ohms. On other bands P1 is disabled. The cable circuit includes n2+n3 coils (6 turns) and the antenna matches 180 Ohms to 50 Ohms.
L1 – extension coil. It will find its application on the 30 m band. The fact is that the third harmonic of the 80 m band does not coincide with the permitted frequency range of the 30 m band. (3 x 3600 KHz = 10800 KHz). Transformer T1 matches the antenna at 10500 KHz, but this is still not enough, you also need to turn on the L1 coil and in this connection the antenna will already resonate at a frequency of 10100 KHz. To do this, using K1, we turn on relay P2, which at the same time opens its normally closed contacts. L1 can also serve in the 80 m range, when we want to work in the telegraph area. On the 80 m band, the antenna resonance band is about 120 kHz. To shift the resonance frequency, you can turn on L1. The switched on coil L1 noticeably reduces the SWR at the 24 MHz frequency, as well as at the 10 m band.
The matching device performs three functions:
1. Provides symmetrical power to the antenna, since the antenna web is isolated at HF from the ground through transformer coils Tr1 and L1.
2. Matches the impedance in the manner described above.
3. Using coils n2 and n3 of transformer Tr1, the antenna resonance is placed in the corresponding, permitted frequency bands by range. A little more about this: If the antenna is initially tuned to a frequency of 3600 kHz (without turning on the matching device), then on the 40 m band it will resonate at 7200 kHz, on 20 m at 14400 kHz, and on 10 m at 28800 kHz. This means that the antenna needs to be extended in each range, and the higher the frequency of the range, the more extension it requires. Just such a coincidence is used to match the antenna. Transformer coils n2 and n3, T1 with a certain inductance, the more the antenna extends, the higher the frequency of the range. In this way, on 40 m the coils are extended to a very small extent, but on the 10 m band they are extended to a significant extent. The matching device puts a correctly tuned antenna into resonance on each band in the region of the first 100 kHz frequency.
The positions of switches K1 and K2 by range are indicated in the table (right):
If the input impedance of the antenna on the 80 m range is set not in the range of 80 - 90 Ohms but in the range of 100 - 120 Ohms, then the number of turns of coil n2 of transformer T1 must be increased by 3, and if the resistance is even higher, then by 4. The parameters of the remaining coils remain unchanged changes.
Translation: UT1DA source - (http://ut1da.narod.ru) HA5AG
SWR meter with matching device
In Fig. shown on the right circuit diagram a device that includes an SWR meter, with which you can tune a CB antenna, and a matching device that allows you to bring the resistance of the tuned antenna to Ra = 50 Ohms.
Elements of the SWR meter: T1 - antenna current transformer wound on a ferrite ring M50VCh2-24 12x5x4 mm. Its winding I is a conductor threaded into a ring with antenna current, winding II is 20 turns of wire in plastic insulation, it is wound evenly around the entire ring. Capacitors C1 and C2 are of the KPK-MN type, SA1 is any toggle switch, PA1 is a 100 μA microammeter, for example, M4248.
Elements of the matching device: coil L1 - 12 turns PEV-2 0.8, internal diameter - 6, length - 18 mm. Capacitor C7 - type KPK-MN, C8 - any ceramic or mica, operating voltage of at least 50 V (for transmitters with a power of no more than 10 W). Switch SA2 - PG2-5-12P1NV.
To set up the SWR meter, its output is disconnected from the matching circuit (in point A) and connected to a 50-ohm resistor (two MLT-2 100 Ohm resistors connected in parallel), and a CB radio station operating for transmission is connected to the input. In the direct wave measurement mode - as shown in Fig. 12.39 position SA1 - the device should show 70...100 µA. (This is for a 4 W transmitter. If it is more powerful, then “100” on the PA1 scale is set differently: by selecting a resistor that shunts PA1 with resistor R5 shorted.)
By switching SA1 to another position (reflected wave control), adjusting C2 achieves zero readings of PA1.
Then the input and output of the SWR meter are swapped (the SWR meter is symmetrical) and this procedure is repeated, setting C1 to the “zero” position.
This completes the adjustment of the SWR meter; its output is connected to the seventh turn of the L1 coil.
The SWR of the antenna path is determined by the formula: SWR=(A1+A2)/(A1-A2), where A1 is the readings of PA1 in the forward wave measurement mode, and A2 is the reverse wave. Although it would be more accurate to talk here not about SWR as such, but about the magnitude and nature of the antenna impedance reduced to the station’s antenna connector, about its difference from the active Ra = 50 Ohm.
The antenna path will be adjusted if by changing the length of the vibrator, counterweights, sometimes the length of the feeder, the inductance of the extension coil (if any), etc. the minimum possible SWR is obtained.
Some inaccuracy in antenna tuning can be compensated for by detuning the L1C7C8 circuit. This can be done with capacitor C7 or by changing the inductance of the circuit - for example, by introducing a small carbonyl core into L1.
As experience in tuning and matching CB antennas of various configurations and sizes (0.1...3L) shows, under control and with the help of this device it is not difficult to obtain SWR = 1... 1.2 in any part of this range.
Radio, 1996, 11
Simple antenna tuner
To match the transceiver with various antennas, you can successfully use a simple hand-held tuner, the diagram of which is shown in the figure. It covers the frequency range from 1.8 to 29 MHz. In addition, this tuner can work as a simple antenna switch, which also has an equivalent load. The power supplied to the tuner depends on the gap between the plates of the variable capacitor C1 used - the larger it is, the better. With a gap of 1.5-2 mm, the tuner could withstand power up to 200 W (maybe more - my TRX did not have enough power for further experiments). You can turn on one of the SWR meters at the tuner input to measure SWR, although this is not necessary when the tuner works together with imported transceivers - they all have a built-in SWR measurement function (SVR). Two (or more) RF connectors of the PL259 type allow you to connect the antenna selected using the S2 “Antenna Switch” slide switch for operation with the transceiver. The same switch has an “Equivalent” position, in which the transceiver can be connected to an equivalent load with a resistance of 50 Ohms. Using relay switching, you can enable the Bypass mode and the antenna or equivalent (depending on the position of the S2 antenna switch) will be directly connected to the transceiver.
As C1 and C2, standard KPE-2 with an air dielectric of 2x495 pF from industrial household receivers are used. Their sections are threaded through one plate. C1 involves two sections connected in parallel. It is mounted on a 5 mm thick plexiglass plate. In C2 – one section is involved. S1 – biscuits HF switch with 6 positions (2N6P biscuits made of ceramics, their contacts are connected in parallel). S2 - the same, but in three positions (2Н3П, or larger number positions depending on the number of antenna connectors). Coil L2 - wound with bare copper wire d=1mm (preferably silver-plated), a total of 31 turns, winding with small pitches, outer diameter 18 mm, bends from 9 + 9 + 9 + 4 turns. Coil L1 is the same, but 10 turns. The coils are installed mutually perpendicular. L2 can be soldered with leads to the contacts of the biscuit switch by bending the coil into a half ring. The tuner is installed using short thick (d=1.5-2 mm) pieces of bare copper wire. Relay type TKE52PD from the radio station R-130M. Naturally, the best option is to use higher frequency relays, for example, the REN33 type. The voltage for powering the relay is obtained from a simple rectifier assembled on a TVK-110L2 transformer and a KTs402 (KTs405) diode bridge or the like. The relay is switched by toggle switch S3 “Bypass” type MT-1, installed on the front panel of the tuner. Lamp La (optional) serves as a power-on indicator. It may turn out that in the low frequency ranges there is not enough capacity C2. Then, in parallel with C2, using relay P3 and toggle switch S4, you can connect either its second section or additional capacitors (select 50 - 120 pF - shown in the dotted line in the diagram).
According to the recommendation, the KPI axes are connected to the control handles through sections of durite gas hose, which serve as insulators. To fix them, water clamps d=6 mm were used. The tuner was made in a housing from the Elektronika-Kontur-80 kit. The somewhat larger housing dimensions than the tuner described in leave sufficient scope for improvements and modifications of this circuit. For example, a low-pass filter at the input, a 1:4 matching balun transformer at the output, a built-in SWR meter and others. For efficient work The tuner should not be forgotten about its good grounding.
A simple tuner for tuning a balanced line
The figure shows a diagram of a simple tuner for matching a symmetrical line. An LED is used as a setting indicator.
When working in the field, at the dacha or on an expedition, it is not always possible to use resonant antennas for each band. The choice of their design depends on the location of the radio station and the availability of supports for installing the antenna.
In many cases, it is possible to use only non-resonant wire antennas, or it is difficult to tune the antennas to resonance due to the lack of necessary instruments and time for this. To successfully work with non-resonant antennas, it is necessary to use matching devices (MD).
Fig.1.
The control systems used in QRP expeditions have their own characteristics. They must be light in weight, have high efficiency and withstand power up to 50 watts. Most known matching devices incorporate variable inductance.
It is difficult to create a small-sized control system using variable inductances, which must have sufficiently large dimensions for the control system to operate effectively.
Therefore, two matching devices were made using only variable capacitors to configure them. One was designed to operate in the frequency range 1.8-14 MHz, the other for the range 18-30 MHz.
The control system circuit for 1.8-14 MHz is shown in Fig. 1, and for 18-30 MHz - in Fig. 2. When the low-frequency control system operates at 160 meters in parallel with C1, an additional capacitor C2 with a capacity of 560 pF is switched on.
When working on 40, 30 and 20 meters, the L2 part of the coil is used. C1 and C4 (Fig. 1) are variables, dual with an air dielectric with a maximum capacity of 495 pF. Sections of these capacitors are connected in series to increase the operating voltage.
The control system uses variable capacitors of the KPV type with a maximum capacitance of 100 pF for operation in high-frequency ranges. Each control system has an RF ammeter in the antenna circuit. The transformer used in it contains 20 turns of secondary winding. Primary winding- antenna wire threaded through the ring.
For current transformer you can use ferrite ring external diameter from 7 to 15 millimeters and permeability 400-600. You can also use high-frequency ferrites with a permeability of 50-100, in this case it is easier to obtain a linear frequency response of the antenna current meter.
Fig.2.
To linearize the frequency response of the current meter, it is necessary to use a shunt resistor R1 of the smallest possible value. But the smaller it is, the lower the sensitivity of the antenna current meter. The compromise value of this resistor is 200 Ohms. In this case, the sensitivity of the ammeter is 50 mA.
It is advisable to use standard instruments to check the correctness of the ammeter readings when working on different ranges. Using resistor R2, you can proportionally reduce the readings of the device. This makes it possible to measure the current of both high-impedance and low-impedance antennas.
The current of high-impedance antennas lies in the range of 50-100 mA with a power supplied to them of 10-50 W.
The inductors for the control system in Fig. 1 are wound on a frame with a diameter of 30 mm, L1 - 5 turns of PEL 1.0 in the lower part of L2, winding length 12 mm, L2 - 27 turns of PEL 1.0 with a tap from the 10th turn counting from the grounded end, winding length 55 mm. Inductors for the control system in Fig. 2 are on a frame with a diameter of 20 mm, L1 - 3 turns of PEV 2.0, winding length 20 mm, L2 - 14.5 turns of PEV 2.0 with a winding length of 60 mm.
Settings
The SU is used as follows. Connect it to the transceiver, ground and antenna. The coupling capacitor C4 (Fig. 1) or SZ (Fig. 2) is brought to a minimum. Using C1, the circuit is tuned to resonance according to the maximum glow of the VL1 neon. Then, by increasing the capacitance of the coupling capacitor and decreasing the capacitance of the loop capacitor C1, we achieve maximum current transfer to the antenna. Matching devices (Fig. 1, Fig. 2) provide matching of loads with resistance from 15 ohms to several kiloohms.
The control system for low-frequency ranges was made in a case made of foil fiberglass with dimensions of 280 * 170 * 90 mm, the control system for high-frequency ranges was made in the same case with dimensions of 170 * 70 * 70 mm.
Even 10...15 years ago there were practically no problems with the use of matching devices (CDs), and accordingly there were almost no descriptions of such devices in amateur radio literature.
The point is probably that previously in the USSR almost everyone used homemade tube equipment, the output stage of which could be matched with almost anything.
Transistor RAs produce much more harmonics than tube ones. And often the low-Q P-circuit at the output of the transistor PA cannot cope with their filtering. In addition, we must take into account that the number of TV channels has increased many times compared to what it was just a few years ago!
Purpose of the matching device
The control system ensures the transformation of the transmitter output impedance into the antenna impedance. It is irrational to use a control system with a tube power amplifier that has a P-circuit with all three continuously variable elements, since the P-circuit provides matching over a wide range of output impedances. Only in cases where the elements of the P-circuit exclude adjustment, the use of control system is beneficial.
In any case, the control system significantly reduces the level of harmonics, and its use as a filter is fully justified.
If you have good tuned resonant antennas and good PA, there is no need to use a matching device. But when one antenna operates on several bands, and the radio antenna does not always produce what is needed, the use of control system gives good results.
Principles for constructing a matching device
The classic control system has the form shown in Fig. 1. As you can see, it consists of a matching circuit (MC), which is made according to one of the well-known schemes (the MC itself is often called a “matching device”, “ATU”), an SWR meter, an RF bridge showing the degree of antenna mismatch, an equivalent antenna R 1, and control loads R2, R3. Without all this “environment” the control system is just a coordination chain, nothing more.
Fig.1
Let's look at the principle of operation of the device. In position S 1 “Bypass”, the transmitter output is connected to S2, which makes it possible to either directly connect the antenna, or connect one of the load equivalents (R2 or R3) to the output and check the possibility of matching the transmitter with it. In the "Setting" position, the transmitter operates at a matched load. Also, the RF bridge is switched on through resistance R4. Based on the balance of this bridge, the antenna is tuned using a matching circuit. Resistors R2 and R3 make it possible to check whether it is possible to configure the matching circuit on them. Having configured the CA, turn on the “Operation” mode. In this mode, the matching circuit is further adjusted to the minimum readings of the SWR meter.
Below we will consider the main CAs used in practice.
Matching circuit on a parallel circuit
One of the most effective and easily implementable CAs is shown in Fig. 2. The transmitter is connected via coil L1 and capacitor C1. L1 is from a quarter to a sixth of the number of turns of L2 and is wound in its lower part. L1 must be separated from L2 by high-quality insulation.
Fig.2
In this scheme, the transmitter is connected to the DS only by magnetic flux, and here the issue of lightning protection of the output stage is automatically resolved. Capacitor C1 for operation at 1.8 MHz. must have a maximum capacitance of 1500 pF, and for operation at 28 MHz - 500 pF. C2 and C1 should have the maximum possible gap between the plates. The load resistance range is from 10 ohms to several kiloohms. High efficiency operation is ensured in two adjacent ranges, for example 1.8 and 3.5 MHz. To operate effectively in multiple bands, it is necessary to switch L1 and L2. At low powers (up to 100 W), it is most effective and simple to make a set of replacement coils and install them using plinth panels from old radio tubes. Any experiments related to connecting L1 and L2 coils in parallel to reduce their inductance for operation in the HF range, connecting to the taps of these coils, or “tricky” parallel connection of the coils significantly reduces the efficiency of this DS at HF. The coil data for the circuit in Fig. 2 is given in Table 1.
Table 1
Although symmetrical antennas are rarely used at present, it is worth considering the possibility of operating this DS for a symmetrical load (Fig. 3).
Fig.3
Its only difference from the diagram in Fig. 2 is that the voltage for the load is removed symmetrically. L1 should be located symmetrically relative to L2. Capacitors C 1 and C2 must be on the same axis. It is necessary to take measures to reduce the influence of the capacitive effect on L2, i.e. it should be located far enough from the metal walls. L2 data for the circuit in Fig. 3 are given in Table 2.
table 2
There are also designs of a simplified version of this CA.
Fig.4
Figure 4 shows an asymmetrical circuit, Figure 5 shows a symmetrical one. But, unfortunately, as experience shows, these circuits cannot provide such careful coordination as in the case of using capacitors C3 (Fig. 2) or C3.1, C3.2 (Fig. 3).
Fig.5
Particular care must be taken in the construction of multi-band digital systems operating on this principle (Fig. 6). By reducing the quality factor of the coil and large capacity taps "to ground" the efficiency of such a system in the HF ranges is low, but the use of such a system in the ranges of 1.8...7 MHz is quite acceptable.
Fig.6
Setting up the CA shown in Fig. 2 is simple. Capacitor C1 is placed in the maximum position, C2 and C3 in the minimum position, then with the help of C2 the circuit is adjusted to resonance, and then, increasing the connection with the antenna with the help of C3, they achieve maximum power output to the antenna, all the while adjusting C2 and, according to opportunities, C1. You should strive to ensure that, after configuration, the C3 CA has maximum capacity.
T-shaped matching circuit
This scheme (Fig. 7) has become widespread when working with asymmetrical antennas.
Fig.7
For normal operation of this DS, smooth adjustment of the inductance is necessary. Sometimes even half a turn is critical to matching. This limits the use of tapped inductance or requires individual selection of the number of turns for a specific antenna. It is necessary that the capacitance of C1 and C2 to ground be no more than 25 pF, otherwise the efficiency may decrease by 24...28 MHz. It is necessary that the "cold" end of the L1 coil be thoroughly grounded. This CA has good parameters: Efficiency - up to 80% when transforming 75 Ohms into 750 Ohms, the ability to match loads from 10 Ohms to several kiloohms. Using only one variable inductance of 30 μH, you can cover the entire range from 3.5 to 30 MHz, and by connecting 200 pF constant capacitors in parallel with C1, C2, you can work at 1.8 MHz.
Unfortunately, variable inductance is expensive and complex in design. W3TS proposed a switchable "digital inductance" (Fig. 8). Using such inductance, you can clearly set its desired value using switches.
Another attempt to simplify the design was made by the AEA company, making a matching device according to the diagram shown in Fig. 9. Indeed, the diagrams in Fig. 7 and Fig. 9 are equivalent. But structurally it is much simpler to use one grounded high-quality capacitor instead of two isolated ones, and replace the expensive variable inductance with cheap permanent inductors with taps. This DS worked well from 1.8 to 30 MHz, transforming 75 Ohms into 750 Ohms and into 15 Ohms. But when working with real antennas, the discreteness of inductance switching sometimes affected it. If there are 18, or better yet 22, position switches, this design center can be recommended for practical use. In this case, it is necessary to reduce the length of the coil leads to the switch to a minimum. Switches for 11 AEA AT-30 TUNER L1-L2-25 Turns, dia. coils 45 mm winding pitch 4 mm taps from each turn along the length of 10 turns then after 2 turns of positions make it possible to make a central coil only for working on a part amateur bands- from 1.8 to 7 or from 10 to 28 MHz.
Fig.9
It is convenient to construct the coil as shown in Fig. 10. Its frame is a strip made of double-sided fiberglass with cuts for the turns of the coil. A switch is installed on this bar (for example 11P1N). Taps from the coil go to the switch on both sides of the fiberglass strip.
Fig.10
When working with symmetrical antennas, together with a T-shaped matching device, use a 1:4 or 1:6 balun transformer at the output of the central station. Such a solution cannot be considered effective, because many symmetrical antennas have a large reactive component, and ferrite transformers perform very poorly with reactive loads. In this case, it is necessary to apply measures to compensate for the reactive component or use a CS (Fig. 3).
U-shaped matching scheme
U-shaped CS (or U-circuit), the diagram of which is given in Fig. 11, is widely used in amateur radio practice.
Fig.11
In real conditions, when the transmitter output is 50...75 Ohms, and matching must be done in a wide range of load resistances, the parameters of the P-circuit change tens of times. For example, at 3.5 MHz with Rin = Rn = 75 Ohm, the inductance L1 is approximately 2 μH, and C1, C2 - 2000 pF each, and with Rin = 75 Ohm and RH of several kiloohms, the inductance L1 is approximately 20 μH, the capacitance C1 is about 2000 pF, and C2 - tens of picofarads. Such large variations in the values of the elements used limit the use of the P-circuit as a central circuit.
It is advisable to use variable inductance. Capacitor Cl may have a small gap, and C2 should have a gap of at least 2mm for every 200W of power.
Increasing the efficiency of the matching device
A device called an “artificial earth” helps increase transmitter efficiency, especially when using random antennas. This device is effective when using random antennas and poor radio grounding. This device brings the radio station's grounding system (in the simplest case, a piece of wire) to a resonant state. Since ground parameters are part of the antenna system parameters, improving ground efficiency improves antenna performance.
Conclusion
The matching device should not be used more often than it is really needed. You should select the type of control system that you need. For example, there is no point in making a broadband device to operate in the range of 1.8...30 MHz, if in reality you do not “build” antennas for 1...2 bands, or if you use surrogate antennas on these bands. Here it is much more efficient to perform its own separate control system for each range. But of course, if you are using a transceiver with a non-adjustable output, and most of your antennas are surrogate, then an all-band control system is needed here.
All of the above applies to the “artificial earth” device.
Fig.12
Literature
1. Podgorny I. (EW1MM). HF Grounding / Amateur Radio KB and VHF. - 1995. - No. 9.
2. Grigorov I. (RK3ZK). Matching device on a coaxial cable / Radio amateur. - 1995. - No. 7.
3. Podgorny I. (UC2AGL). Antenna tuner/Amateur radio. -1994.-No. 2.
4. Podgorny I. (UC2AGL). Antenna tuner/Amateur radio. -1991.-No. 1.
5. Grigorov I. (UZ3ZK). Universal matching device // Radio amateur. - 1993. - No. 11.
6. Padalko S. (RA6LEW). Antenna switching-matching device / Radio amateur. - 1991. - No. 12.
7. Orlov V. (UT5JAM). All-band matching device for LW/Amateur Radio. -1992. - No. 10.
8. Villemagne P. (F9HY). Matching device for LEVY/ /Amateur radio antennas. - 1992. - No. 10.
9. Podgorny I. (EW1MM). Universal antenna matching device / Radio amateur. - 1994. - No. 8.
HF antenna matching devices are necessary for the installation of amateur and professional radio points. As a rule, the cost of such equipment is low. They are sold openly, and to buy matching devices for HF antennas, no special permission is required.
Application area
HF antenna tuners are necessary for almost all people who practice radio communications. HF antenna tuners tend to buy and install in the following categories:
- fishermen, hunters, tourists and other outdoor enthusiasts;
- Truckers and taxi drivers also prefer to install an antenna tuner for the transceiver in their cars;
- Today, Russia cannot boast that there is a stable coating throughout its entire territory. cellular communications. In many populated areas, the only means of communication is a radio station, complete with which people tend to buy a matching device for an HF transmitter.
Based on the above, it becomes clear that an integral part of amateur radio points are not only transceivers, walkie-talkies and antennas, but also tuners. As a rule, the price of such devices is low and affordable for a radio amateur with average income.
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