Amateur radio designs and sale of radio equipment.

As usual, first some background. I somehow decided to get an amplifier for my favorite VHF band, 1200 MHz. But I felt sorry for paying 16-20 thousand rubles for ready-made amplifiers (for example, from Tokyo Hy-Power, PROCO, etc.). And indeed, a thing that is needed 1-2 times a year at competitions like Field Day somehow does not fit with the amount of $700.

So I decided to make the amplifier myself. But the word “self” does not mean “completely itself from 0”, but on ready-made Mitsubishi RA18H1213G modules. It was, of course, possible to completely assemble it from “0” using transistors or tubes, but now it’s not 1980, after all!

DIYers, don't be offended! I am a DIYer myself, I have made everything with my own hands - from the first detector receiver in 1985 to microprocessor control units and frequency synthesizers recently. But doing something that you can easily buy inexpensively is quite a big stupidity and a waste of precious time, which is quite small and which can be spent wisely. O greater benefit.

It seems to me that currently the most optimal ratio of result to cost is obtained by manufacturing an amplifier at 1200 MHz by using something already ready.

And so, for the purpose of conversion to 1200 MHz, an S-50 amplifier was purchased at a Japanese auction for 2000 rubles.

Here is a photo of the completely finished amplifier:

As mentioned earlier and as can be seen from the photo, the amplifier model S-50 of an unknown Japanese company at 900 MHz was taken as the basis (the so-called Personal Radio range - a la 27 MHz in the Japanese version with 5 watt radio stations and a 5-digit personal calling code). The S-50 amplifier included a 3-stage power amplifier 5 -> 50W on 3 powerful transistors, as well as a reception amplifier on 1 transistor, which experienced people identified as MGF-1301.

Here is a photo of a 3-stage PA with 3 transistors that was installed there previously:

I carefully removed this 900 MHz 3-stage power amplifier board from the case, and easily rebuilt the reception amplifier from 900 to 1200 MHz by unsoldering the capacitor at the input. In principle, a reception amplifier is a rather useless thing if it is installed directly next to the transceiver. Now, if only it were on the roof, closer to the antenna... But since it is there, let it be, at least to compensate for losses in the connecting cables and amplifier switches.

By the way, the OMRON GY-154P relays installed in the switching and receiving part of the S-50, although designed to operate at frequencies of 900 MHz maximum, have characteristics acceptable from my point of view at a frequency of 1295 MHz: the measured SWR was 1.6. Perhaps OMRON G6Y or G6Z relays would be better suited here, with operating frequencies up to 2-2.5 GHz, but I was just too lazy to solder them. Maybe I'll try it in the future. I have the G6Z relays themselves, 2 of them.

For the basic circuit of the 1200 MHz amplifier, we took the 7L1WQG amplifier design on two RA18H1213G modules, see Appendices 1 and 2.

The 1200 MHz amplifier printed circuit board was purchased at a Japanese auction for 2000 rubles. It is still sold there, see Appendix 7. You could, of course, try to make it yourself, but it seemed to me that it would be somehow difficult to make a double-sided board with metallization of the through holes at home.

The RA18H1213G-101 modules themselves, 2 pieces, were purchased from the company Sycamore, from whom I had a pleasant experience working with. The modules ultimately cost 2050 rubles. per piece including postage. Here I would like to highlight the question of how the RA18H1213G “simply” modules differ from the RA18H1213G-101? There was no clear answer to this question at the time of manufacture of this amplifier. The RA18H1213G modules were “simply” significantly more expensive than the RA18H1213G-101. The sellers themselves usually vaguely denied that this was to differentiate between new and old batches of goods. It was experimentally found that the RA18H1213G-101 modules reach operating mode at a voltage at the transistor gates of about 4-4.2 volts, and the RA18H1213G “simply” at 5 volts, judging by information from the Internet. This is also indicated by the layout of the 7L1WQG amplifier printed circuit board. I myself haven’t “simply” touched the RA18H1213G modules, so if I’m wrong, correct me.

If you apply 5 volts to the RA18H1213G-101 module, it will switch to Super A mode - the quiescent current of each module will be about 7-8 amperes!

In general, we consider the main costs for this amplifier: 2000 rubles (for S-50) + 2000 rubles (for printed circuit board) + 4100 rubles (for 2 RA18H1213G modules) = 8100 rubles. I think it's acceptable :)

To be fair, we need to add a fan with a beautiful grille (300 rubles) and a 1.5 meter power cord (90 rubles), but these are, in principle, trifles.

I want to say something special about the power cord - initially from the factory this cord had a cross-section of 2.5 square meters. mm., which was clearly not enough: over a length of 2 m, 1.4 volts dropped at a current of 20 A. That's as much as 10%! I found this unacceptable and changed it to 1.5 meters with a cross section of 4 square meters. mm. Now for a loss of 0.6 volts at a current of 20 a. you can just ignore it :)

As I wrote above, the RA18H1213G-101 modules are designed for a bias voltage of 4-4.2 volts, and the design of the 7L1WQG printed circuit board is designed for RA18H1213G modules, which operate at a bias of 5 volts. The 5 volt voltage is taken there from the 5 volt integrated voltage stabilizers initially installed on the board. In order to reduce the voltage from 5 to 4 volts, I had to install ordinary 500 Ohm trimming resistors (clearly visible in the 7th photo). The PCB design made this easy. But even a quiescent current of a couple of amperes is too high for a Field Day, and such a “stove” is not needed at home either. Therefore, a voltage of 12-13 volts is supplied to the 5-volt stabilizers at the time of transmission through a transistor switch on a P-N-P transistor 2SB1367 (penultimate photo).

The unit for smooth control of the fan rotation speed was made on the power regulator present in the amplifier, consisting of a variable resistor on the front panel and a composite transistor 2SD1590 (last photo). From my point of view, it is much more convenient to have a smooth control of the fan speed than to turn it on only at the moment of transmission, as is done in most transceivers, or to have it spinning constantly.

I used the 3 LEDs in the amplifier to indicate the inclusion of the power amplifier (green), the reception amplifier (yellow) and the indication of the transition to transmission (red).

A few words about the design of 7L1WQG. In the 9th photo you can see a trimming capacitor of several picofarads for fine-tuning the input of each module.

In the 8th photo you can see a 1 pf capacitor connected to the amplifier output. Needed to obtain maximum power at a given frequency. Recommended capacity - 0.5...2 pF.

Well, in conclusion, I will intimidate you a little for your own benefit, my dear readers :)

Let's imagine that you assembled such an amplifier and received a power of about 60 watts at 1.2 GHz. Amazing!

Now imagine that you are using a Yagi-type antenna with an average gain of 18 Dbi for a frequency of 1200 MHz (this is about 60 times the power).

Let's imagine that the losses in a short piece of good cable from the amplifier to the antenna are equal to 0.

Now let’s estimate the effective radiated power: 60 watts * 60 times = 3600 watts. 3.6 kilowatts! That's more than a microwave!

To sharpen the sensations, I will change the conditions a little: let our amplifier have not 2, but 4 RA18H1213G modules inside, this is 120 watts at the output. And let our antenna be a stack of 4*48 elements. 26 decibels of gain! This is 1500 times the power. 120 * 1500 = 180 kilowatts! The number is simply monstrous!

SO NEVER STAND IN THE DIRECTION OF THE RADIATION OF MICROWAVE ANTENNAS! AND STRICTLY AVOID DIRECTING MICROWAVE RADIATION INTO YOUR EYES - YOU CAN GO BLIND!

Current consumption - 46 mA. The bias voltage V bjas determines the output power level (gain) of the amplifier

Fig. 33.11. Internal structure and pinout of TSH690, TSH691 microcircuits

Rice. 33.12. Typical inclusion of TSH690, TSH691 microcircuits as an amplifier in the frequency band 300-7000 MHz

and can be adjusted within 0-5.5 (6.0) V. The transmission coefficient of the TSH690 (TSH691) microcircuit at a bias voltage V bias = 2.7 V and a load resistance of 50 Ohms in a frequency band up to 450 MHz is 23 (43) dB, up to 900(950) MHz - 17(23) dB.

Practical inclusion of TSH690, TSH691 microcircuits is shown in Fig. 33.12. Recommended element values: C1=C5=100-1000 pF; C2=C4=1000 pF; C3=0.01 µF; L1 150 nH; L2 56 nH for frequencies not exceeding 450 MHz and 10 nH for frequencies up to 900 MHz. Resistor R1 can be used to regulate the output power level (can be used for an automatic output power control system).

The broadband INA50311 (Fig. 33.13), manufactured by Hewlett Packard, is intended for use in mobile communications equipment, as well as in consumer electronic equipment, for example, as an antenna amplifier or radio frequency amplifier. The operating range of the amplifier is 50-2500 MHz. Supply voltage - 5 V with current consumption up to 17 mA. Average gain

Rice. 33.13. internal structure of the ΙΝΑ50311 microcircuit

10 dB. The maximum signal power supplied to the input at a frequency of 900 MHz is no more than 10 mW. Noise figure 3.4 dB.

A typical connection of the ΙΝΑ50311 microcircuit when powered by a 78LO05 voltage stabilizer is shown in Fig. 33.14.

Rice. 33.14. broadband amplifier on the INA50311 chip

Shustov M. A., Circuitry. 500 devices on analog chips. - St. Petersburg: Science and Technology, 2013. -352 p.

In this article I will describe the methodology for selecting, remaking and customizing industrial samples of products with which I have repeatedly worked. Of all the criteria, the most fully described and, most importantly, easily repeatable option will be taken.

Chapter 1. Method for selecting the type of amplifier.

There are two ways to approach this problem. The first way is a completely homemade finished structure. The second way is when the amplifier is based on an industrial design of the most critical design unit, and further work is carried out independently. Let's focus on this option. The main part in the original design, with an output power of up to 1 kW, is the resonator, as the most complex and critical component.

Let's consider the advantages of an industrial design.

1. Professionally turned on lathe and milling equipment with great precision.
2. Large mass due to the thick walls of the resonator, which improves the mechanical, temporal and frequency stability of the parameters.
3. High quality factor.
4. Inhomogeneity and scattering of the field into the surrounding space are reduced to a minimum.
5. The components for setting it up and connecting it to the antenna are professionally and precisely made.

Flaws:

1. As a consequence of the above, it is weight and the ability to be transported quickly and easily.
2. Difficult to acquire, there are fewer and fewer of them every day.

I will not consider the case with transistor amplifiers because even according to preliminary estimates, it is three to four times more expensive, and the “whims” of the module are great. Strict requirements for the power supply at low voltages and high currents. Protection must be fast, and, if possible, against everything that can be foreseen. When adding output power (not bad when dividing input power), it is advisable to use a circulator for each module. Addition bridges with ballast loads are also needed to absorb the reflected signal, then we can still talk about the reliability of the amplifier. In my opinion, today it is even easier to solve the problem using a lamp.

Having studied the assortment of different blocks and remade a sufficient number of copies, it turns out that the choice is extremely small. The best example is the power amplifier from TRRS R-410M(M1). For this purpose, block 310B of rack 300BM1 is ideally suited. Power amplifier blocks from aviation radio stations R-824, R-831M (R-831 is not suitable at all), R-834(M), R-844M, Sprut-1 have similar parameters. The experience of restructuring shows that it is much easier to lower the resonance frequency than to increase it, as required by the above aviation radio stations. They are designed in such a way that this is a big problem. The technical specifications for these radio stations already allow for a reduction in output power at the HF edge of the range (389.975 MHz). The design of the resonator, although simpler, still has a separation capacitance in the anode, and this is not the best solution. The RF choke in the anode will also add its own capacitance. In addition, a corrective inductance (in the R-831M) is also included in the anode, designed to equalize the load characteristics of the lamp, and this is an additional capacitance to the resonator. With such a set of capacitances, it is no longer possible to tune the resonator to 432 MHz, despite the fact that all unnecessary low-pass filters are disabled. The designers had great difficulty reaching 390 MHz. So aviation radios are not the best solution to the problem for 432 MHz.

Let's return to the R-410M(M1). Developed at MNIRTI, it was produced at the Vladimir Elektropribor plant for almost 30 years, until 1989. During this time, 11 series of radio stations (changes and modifications) were produced.

The 300BM1 rack is a power amplifier rack. In the output stage of the rack there are 2 amplifier blocks 310B on the left and 2 blocks 310B on the right. They are rocked by one block 310B, in turn these blocks are rocked by blocks 320B. The stand operates on two parabolas with horizontal and vertical polarization each. The principle of dual and quadruple reception and transmission is used. In the FM mode, the 310B block delivers 650 W (each) for a long time, this is determined by the protection installed at the factory (block 330 - anode power supply and its protection), with an anode current of 0.4-0.5 A (this mode is recommended by the manufacturer as a mode lamp life, according to reference data). The adjustment is operational, using a potentiometer, up to a maximum anode current of no more than 0.9 A (anode voltage + 2500 V). This is a standard power supply.

So, the 310B block is assembled on a GS-35B lamp according to a scheme with a common grid. Anode voltage +2500 V, anode current 0.7 A, output power about 1 kW. The resonator is smoothly tuned in two ranges.

1. 476 - 525 MHz. (channels 1 to 50)
2. 576 - 625 MHz. (channels 51 to 100)

Resistors R1 and R2 in the cathode circuit create a bias on the lamp grid, but the initial anode current is not large, because World Cup mode was used. With an output power close to 1 kW, to increase efficiency. and reducing swing (with an old lamp), it may be necessary to increase the initial anode current, reducing the value of R1 and R2 to 100-120 Ohms each. But it is best to replace the resistors in the cathode with a chain of zener diodes of the D-815A type. They can easily select the desired initial anode current and ensure that the lamp is turned off during reception (there are a huge number of similar circuits in amplifiers). Resistor R6 is connected to the cathode circuit by the contacts of relay P1, when 27 V is supplied to it. The “work” - “hardening” toggle switch is in the hardening position, and the lamp is locked. The toggle switch is located in block 320 and at the same time from block 330 (anode power supply), only half of the anode voltage is supplied to the lamp anode from the midpoint of the anode transformer (+1250 V). Thus, one half-set can be used at a time for training lamps, which is often done. Resistor R4 is a shunt when measuring the anode current, and R3 is a shunt when measuring the grid current. The anode power supply (block 330) has current protection in the range of 0.4-0.9 A. with operational adjustment.

The resonators of block 310B have the following design. Both resonators are directed in one direction, towards the cathode - this is the best arrangement (unlike aviation radio stations, where the anode resonator is directed in the other direction).

The anode-grid resonator (anode) has a length of about a quarter of the wavelength. The cathode grid resonator (cathode) is about three-quarters of the wavelength long. Only with this combination of resonator lengths can feedback circuits (FOC) be introduced, increasing the stability of the amplifier; at both lengths of a quarter wave, this cannot be done, such amplifiers are prone to self-excitation. Amplifier load 75 Ohm. For a load of 50 Ohms, it is necessary to connect a half-wave section of the 75 Ohm cable between the amplifier and the 50 Ohm cable, because a half-wave section of cable “transmits” a load of 50 Ohms from one end of the cable to the other, i.e. to the amplifier and the matching will be as required.

Advantages of one-sided resonator design:

1. You don't need a stable, high-voltage, microwave isolation capacitor with good TKE in the lamp anode. It introduces losses and degrades the characteristics of the resonator.
2. There is no need for an anode choke, which adds its own capacitance to the resonator, which is also bad.
3. The massive radiator of the lamp is not under HF potential and does not in any way affect the tuning of the resonator (which cannot be said about aviation radio stations, where the massive radiator has a large capacitance in the anode and it is no longer possible to increase the frequency of the resonator). The leakage of the RF field through the radiator is minimized, which makes it easier to blow around the lamp.
4. The anode is grounded at HF ​​using the simplest structural container made of fluoroplastic tape, and power is supplied directly to the anode of the lamp.

This design allows you to make full use of the RF properties of the lamp, which makes setup easier.

Chapter 2. Tuning the resonator, block 310B to a frequency of 432 MHz.

Remaking the block is so simple that it can be done by any person who knows how to work with their hands and will treat it carefully. The method described below is very simple, it is not exclusive, it is widely known to many radio amateurs and approved by them, I am only systematizing it in this article based on my experience.

Only the anode resonator is subject to modification. The tuning frequency of the anode resonator must be shifted slightly downward in frequency. To do this, you need to lengthen it a little or add a small adjustable capacitance to the resonator. It is easier to lengthen the resonator. The experience of remaking many copies shows that it is enough to lengthen it by 14-18 mm. To do this, it is necessary to turn the anode plunger in the opposite direction and the length of the anode chamber will increase. At the same time, in order for the plunger to move as far back as possible (towards the input connector) and rest against the centering washer of the anode resonator, the three rods driving the plunger must be shortened by exactly 20 mm. This must be done slowly and carefully. Unfold the plunger and reassemble the resonator in reverse order. The general view of the block is shown in photo 1 and photo 2.

2.1. Resonator disassembly sequence.

Unsolder the filament (green) and cathode (yellow) wires from the unit support post. Photo 3 shows the outer part of the anode resonator.

1. Anode flange 5, steel, next to it is a sealing stocking made of braided shielded wire (reduces RF field leakage).

2. Take out the anode ring 7 (current collection) with the anode separation capacitance C1, made of fluoroplastic -4 (according to technical specifications), pos. 6 and pos. 8. Handle 8 with care - this is a 0.28 mm thick ring made up of 14 chords (half rings) each 0.02 mm thick. If some of them are torn, which happens quite often when the lamp is removed without a puller, cut out new ones.
P.S. There are two different designs for this anode part.

3. Unscrew the four M3 screws and remove the antenna probe 10 with connector from the anode cylinder 9.

4. At the back of anode cylinder 9, unscrew six M4x15 screws (from the end) and slowly pull it forward (towards container C1).
P.S. There are two mounting options, not only from the rear end, but also from the side with M3x10 screws.
A section of the outer part of the anode resonator is shown in Fig. 1.

5. On the grid resonator 11 (the internal cavity of the anode resonator) two negative feedback loops (NFLs) are visible, which is necessary to increase the stability of the amplifier from self-excitation. Handle the loops carefully, see photo 4.

6. Rotating the anode adjustment gear, lower plunger 12 almost close to the OOS loops. Next, use a powerful screwdriver to unscrew the three M4x12 countersunk screws on the gearbox and release the rods 14 from the gearbox, see photo 5.

7. Unscrew the grid resonator from the cathode resonator using five M3x10 screws in the rear part, at the input connector, around the perimeter.
P.S. There are two versions of this rear part of the resonator.

8. Unscrew the three M3x10 screws holding the centering washer 13 of the anode resonator, see Fig. 2 and photo 5, so that it is in a free position. Mark it on the outside with a mark so that you can see how it stood before for reassembly. If washer 13 is not unscrewed, then when you remove the grid resonator, the tips of the screws can cut the fluoroplastic washer 16. Take this into account when reassembling.

9. Slowly pull the grid resonator forward (towards the lamp).
Figure 2 shows a cross-section of the grid resonator.

10. So the mesh cylinder is released, see Fig. 2. and photo 5. It shows that plunger 12 is directed backwards by sliding contacts (towards the gearbox). Next, unscrew, rotating along the axis, rods 14 from plunger 12. Take out washer 13 back (towards the gearbox), then plunger 12. So the unit is disassembled, see photo 6.

11. Wash everything that has been disassembled (except for the inside of the cathode resonator). Take different flute brushes and wash everything with soap and water. Resonators should shine. Where the eaten points are marked on the body, carefully use a scalpel to scrape them out and deep scratches too. Next, but not much, very soft and preferably with a good imported eraser, polish them and the oxides too. Don't rub too much, just a little. This is necessary so that when adjusting the plunger does not add more scratches to you.

12. Cathode resonator 15 cm. Photo 7. can be cleaned with cotton wool soaked in alcohol using a thin long screwdriver. There is a worm inside to move its plunger.

Figure 3 shows a cross-section of the cathode resonator. It is about three-quarters of a wavelength long, and to reduce its size, it was folded in half. For ease of adjustment, both halves are placed coaxially, i.e. one inside the other, this makes it easier for the plunger to move. Only the internal part of the resonator is rebuilt, the external part is not rebuilt. The lamp is connected through capacitor C2 to their common point, i.e. almost to the middle of the three-quarter line, and the input connector is completely included in the line (resonator). If the worm works hard, then by moving it to the lamp, you can drop a little oil and drive it along its entire length. This must be done carefully, without damaging the fluoroplastic tape (capacitor C2). Be sure to check with a tester for a short circuit (some resistance) of the cathode to the housing; there should not be one.

Shorten rods 14 to a length of 20 mm (a little more is possible, but all three are synchronous) in any way convenient for you. It is necessary to take into account that they are made of tool steel grade 40X and are hardened (cemented) on the outside. Hardening depth is about 0.4 mm. Personally, I trim from the narrow side on a lathe with a carbide cutter, then grind it to a diameter of 4 mm. and cut the thread with a die, pressing it from behind. Three rods take about 40-60 minutes if you work slowly.

The resonator is assembled in the reverse order.

2.2. Resonator reassembly sequence.

Chapter 3. Final amplifier assembly.

When finalizing the amplifier, you need to decide how it will be used. It can be used with a separate feeder for transmission, or with one common feeder, according to the classical scheme. Both cases have their pros and cons. Each radio amateur decides for himself what to do.

Let's consider the first case with a separate feeder. If the feeder is 75 Ohm, then no questions arise here; we use direct connection. If the feeder is 50 Ohms, then between the amplifier and the rear (front) panel with antenna connectors, you need to solder sections of 75 Ohm cable, half a wavelength in the cable at a frequency of 432 MHz. (as well as the length of a multiple of half a wave - this is a wave, one and a half waves, etc.), but not a quarter wave. On the amplifier side, the cable is soldered to the standard 75 Ohm connectors, and on the rear panel to the connectors you need.

For a cable with continuous polyethylene insulation, the lengths of the segments are equal to:
228 mm. - half wave, 456 mm. - wave, 684 mm. - one and a half waves, etc.
For a cable with continuous fluoroplastic insulation, the lengths of the segments are equal to:
241 mm. - half wave, 482 mm. - wave, 723 mm. - one and a half waves, etc.

The soldered connectors fit into the length of the cable length.

The second case is with one feeder. If the feeder is 75 Ohm, then REV-15 relays with a classic switching circuit are used. If the feeder is 50 Ohm, then it is necessary to use the same sections of cables as in the case of one feeder. Next is the REV-15 relay, and again the same sections of cable from the relay to the rear panel. Between the relays there is the same 75 Ohm piece of cable. This option with the REV-15 relay is much cheaper than with a 50 Ohm cable and the REV-14 relay. At the same time, the coordination in both options does not differ from each other in any way. But in Moscow, at the Mitinsky radio market, there are a lot of REV-15 relays and you can buy them for 200 rubles, and you still need to look hard for the REV-14 relay and cheaper than 1500 rubles. difficult to find.

Cooling the amplifier is carried out as follows. At the back of the anode flange it is necessary to attach a turbine operating on suction from the lamp, with a capacity of at least 150-200 cubic meters per hour, but 250-280 cubic meters per hour is better. And it’s quite good if you also blow air with a small turbine into the cathode pipe. The air will pass through the cathode resonator and exit out of the grid resonator (cylinder on the sides). It is better to install it directly inside the resonator, discarding the flexible air duct. It is better to make the transition between the cathode nozzle and the turbine outlet gentle in order to exclude vortex flows inside that slow down the air movement.

In this article, I briefly summarized my work experience and my vision of the task in such amplifiers, but everyone has the right to make a decision at their own discretion.

I wish you success.

Alexander. RV3AS. e-mail: This e-mail address is being protected from spambots. To view it, you must have JavaScript enabled

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