HF amplifier made with the left hand. Power amplifier on IRF630 for HF radio station

Power amplifier based on IRF630 for HF radio station The IRF630 was taken as the basis of the amplifier as the cheapest and most common transistors. Their price ranges from $0.45 to $0.7.
Their main characteristics: UCi max = 200 V; 1s max. = 9 A; U3i max = ±20 V; S = 3000 mA/V; Szi = 600...850 pF (depending on the manufacturer); SSI - no more than 250 pF (actually measured SSI on 10 transistors from different manufacturers - about 210 pF); dissipated power Рс – 75 W.

IRF630 transistors are designed to operate in pulsed circuits (scanning computer monitors, switching power supplies), but when put into a mode close to linear, they also give good performance in communication equipment. According to the results of my “laboratory work”, the frequency response of these transistors, if you try to compensate the input capacitance to the maximum extent, is no worse than that of the KP904. In any case, installing them instead of KP904, I got much better results both in terms of frequency response, linearity and gain, and in operational reliability.

The power amplifier on the IRF630 for an HF radio station was tested with a supply voltage of 36-50 V, but it worked most reliably and efficiently with a supply voltage of 40 V, from a stabilized source. The amplifier was designed for an output power of 80 W in order to maintain operational reliability, although more than 100 W could be pumped out of it. True, the reliability of the transistors decreased.

Considering the input capacitance of the IRF630 and the fact that these transistors are controlled not by current, but by voltage, unlike bipolar ones. In this amplifier, it was not possible to eliminate some of the frequency response rollover above 18 MHz (Pout 30 MHz; 0.7Pout max), although circuit engineering measures were taken. But this is inherent in many circuits, including bipolar transistors.

The linear characteristics of the amplifier are good, efficiency; 55%, which confirms the data presented in the article mentioned above. The most important thing is the low cost of components, including transistors. Which can be freely purchased at radio markets and from companies involved in the repair of computer monitors and power supplies. To obtain the calculated power, a signal of no more than 5 V (rms) into a 50 Ohm load must be applied to the amplifier input.

If necessary, the gain can be reduced. By reducing the resistance R1, R12, R13 (Fig.), the remaining characteristics will remain virtually unchanged. But do not forget that the breakdown voltage of the transistor gate does not exceed 20 V, i.e. Uin.eff.max. need to be multiplied by 1.41.

A pre-amplifier is assembled on VT1, which is covered by two OOS circuits - R1, C6 (linearizes the operation of the transistor and prevents self-excitation by reducing the gain) and R5, C7 * (frequency-dependent OOS, correcting the frequency response in the “upper” ranges). At VT2, VT3, a push-pull final stage is assembled with separate bias setting circuits and OOS circuits similar to the first stage.

P-filters L2, C32, SZZ, C37, C38 and L3, C35, C36, C40, C41 serve to bring the output resistance VT2, VT3, which is about 15 Ohms, to 25 Ohms. At the same time, it is a low-pass filter with a cutoff frequency of about 34 MHz. After the power addition transformer TZ, the output impedance of the amplifier becomes 50 Ohms. VD1-VD6 – detector of the ALC system and overvoltage indicator in the drain circuit of the output transistors, assembled on VD7, VD8, R21, C39 (when the peak voltage at the drains VT2, VT3 reaches more than 50 V, the VD7 LED “lights up”, which indicates an increased SWR ).

By activating the control voltage for the ALC circuits, which will change the power level. Depending on the output voltage level, the LED will not “light up”. In any case, you need to remember that the transistor output stages must be connected to the antenna through a matching device. After all, an antenna is not an active load, and behaves differently on each band, even if it is written that it works on all bands.

The installation of the power amplifier on the IRF630 for the HF radio station is made on a board made of double-sided fiberglass, on which rectangular contact pads for the circuit nodes and the “common wire” are cut out with a scalpel. A strip of metallization of the “common wire” is left along the contour of the board.

The contact pads of the “common wire” are connected by through jumpers with continuous metallization of the second side of the board after 2…3 cm. The parts are placed in the order shown in the diagram (Fig.). About a dozen amplifiers were made this way. During the adjustment process, they showed good repeatability, high-quality and reliable operation.

Power amplifier switching board on IRF630 for HF radio station:

performed in any way and connected by wires to the amplifier, the relays are located at the input and output of the amplifier, and their control is connected to the switching board. The adjusted resistors R1, R2, R3 (Fig. 2) must be used multi-turn, having previously installed their motors in the lower position according to the diagram. To ensure that when setting the quiescent current, a sudden movement does not damage the transistors.

Resistors are introduced into the source circuits of all transistors (Fig. 1), which reduce their slope by a “constant”, and thereby additionally protect them. These measures were taken after, having gained experience working with such transistors and throwing a dozen and a half in the trash, I realized that such a DC slope was not needed. Setting the initial current of each output transistor separately is done so that there is no need to sort through a bunch of transistors.

The quiescent currents of VT1 are preliminarily set to about 150 mA and VT2, VT3 - 60-80 mA, but the same in each arm, and more precisely, using a spectrum analyzer. But, as a rule, it is enough to simply set the quiescent currents correctly.

Now let's talk about how to install transistors. The housing of these transistors (TO-220) resembles the “plastic” KT819 with a drain outlet on a metal substrate and a metal flange. There is no need to be afraid of this and you can mount them on the radiator next to the power amplifier board on opposite sides through mica spacers. But the mica must be of high quality and pre-treated with a heat-conducting paste free of sand. The author draws attention to this due to the fact that not only constant voltage is applied to mica, but also HF voltage.

The structural capacitance of the fastener through mica is included in the capacitance of the P-filters, as well as the output capacitance of the transistors. It is better to press the transistors to the radiator not through a hole in the flange, but with a duralumin plate that presses two output transistors at once, which ensures better heat transfer and does not disturb the mica. VT1 has the same fasteners, only at the beginning of the board.

Transformers are wound on ferrite rings of the NN grade and, depending on availability, with a permeability from 200 to 1000. The dimensions of the rings must correspond to the power, I used 600NN K22x10.5x6.5. Winding was carried out using PELSHO-0.41 wire for T1 (5 turns in three wires, 4 twists per centimeter) and PEL-SHO-0.8 for T2 (4 turns in two wires, 1 twist per centimeter), TZ (6 turns per two wires, 1 twist per centimeter). Due to the fact that it is not always possible to find a wire of the required diameter in silk insulation. Winding can also be done with PEV-2 wire, making sure to “ring” the windings together after winding the transformer.

Before winding, the rings are wrapped in a layer of varnished cloth.

The winding data for each transformer depends on the brand and size of the rings used, and in the case of using other rings they can easily be calculated using formula 12 [S.G. Bunin and L.P. Yaylenko. “Handbook of shortwave radio amateurs”, Kiev, “Technique”, 1984, p. 154], where the value of Rk for T1 is 50, for T2 -15, for TZ - 25.

L2, L3 each have 5 turns of PEV-1.5 wire on a mandrel with a diameter of 8 mm, winding length 16 mm. If this data is completely saved, there is practically no need to adjust the filters. L1 - a standard 100 µH inductor must withstand a current of at least 0.3 A (for example, D-0.3). The capacitors in the output low-pass filters are tubular or any high-frequency capacitors with the appropriate reactive power and operating voltage. Similar requirements apply to C26 -C31.

All other capacitors must also be rated for the appropriate operating voltages. After turning on and setting all DC modes, connect the load and adjust the amplifier's frequency response using the GSS and a tube voltmeter or frequency response meter (the author used X1-50). By selecting C7, C10, C19-C22, you can correct the characteristic in the region of 14-30 MHz (Fig. 1). To “level” Pout on the HF bands, you may additionally need to select the number of cue balls for T1 and T2.

The tube HF power amplifier is assembled using 4 GU-50 lamps. Connected in parallel according to a circuit with common grids, and is designed to operate in the ranges of 80, 40, 30, 20, 15 and 10 m. If the amplifier is installed in accordance with the requirements for such devices, neutralization of the throughput capacitance of the lamps is not required. The maximum output power of the amplifier is 350 - 400 W. Two power transformers are used to power the amplifier. The outputs of the rectifiers on diodes VD1 - VD4 and VD5 - VD8 are connected in parallel and loaded onto a capacitive filter (electrolytic capacitors C1 - SZ). A high-resistance resistor and a small capacitor are connected in parallel to each rectifier diode. This increases the electrical “strength” of the rectifiers and reduces output voltage ripple. The anode voltage is approximately 1000 V.
Amplifier

A constant voltage of +15 V is obtained at the output of the half-wave rectifier VD9-C4 and is used to power relays and LEDs indicating the operating mode of the amplifier.
The filament voltage is supplied to the lamp heaters through the inductor Dr6.
A low-pass filter C6-L1-C7 with a cutoff frequency of about 30 MHz is installed at the amplifier input. However, given that the input impedance of the amplifier is quite low and varies depending on the range. It is advisable to install a matching device between the amplifier and the transceiver. An amplifier well matched to the transceiver with a low excitation power (about 50 W) allows you to obtain an output power of 400 W (and even more!). And it provides a spectrally pure signal at the output (of course, if the transceiver and amplifier are working properly and operating in nominal modes).

If a tube HF power amplifier will be used with a transceiver,

at the output of which a P-circuit is installed. Then, when using a short connecting cable between these devices, a matching device is not required. A traditional P-circuit is installed at the output of the amplifier, but since The “anode” capacitor of variable capacitance C11 has a small initial and maximum capacitance; capacitor C12 is connected in parallel to it in the range of 80 m.
When the contacts of switch S2.1 are closed, relay K1 is activated, with the help of the contacts of which the transceiver output is connected to the amplifier input. The amplifier output is to the antenna, and the cathodes of the lamps VL1 - VL4 are to the common wire (through resistor R2).

The anode choke Dr7 is wound on a 40 mm ribbed ceramic frame and contains 30 turns of 0.5 mm wire.
Resistor R2 consists of two 1 Ohm resistors connected in parallel.
Coil L1 is frameless, wound with 0.1 mm wire on a 12 mm mandrel and contains 11 turns, coil L2 - 9 turns of 3 mm silver-plated wire wound on a ribbed ceramic frame. The position of the taps is selected when setting the SWR at the output of the amplifier and should not exceed 2. In addition, it is recommended to connect the antenna to the amplifier through low-pass filters, and to use forced cooling during long-term operation in transmit mode.

The diagram in Splan format can be downloaded

tube, transistor

As practice shows, few radio amateurs work QRP, while most sooner or later begin to dream of increasing the transmitter power. That's when and the question arises about preference to a lamp or a transistor. Long-term practice of operating both of them has shown that tube amplifiers are much simpler to manufacture and less critical to operating conditions, and the weight of the anode transformers is practically compensated by the weight of the radiators necessary for cooling powerful transistors, which are more capricious in operation, especially to overloads, so experiments with they are quite expensive. It is easier to make a power supply with a power of 2 kW at 2000 V at a current of 1 A than 20 V at a current of 100 A. The presence of small-sized electrolytic capacitors designed for high voltage and large capacity allows you to create small-sized high-voltage sources for tube amplifiers directly from the network without using power transformers.

The power amplifier is one of the main attributes of a contestant's and DX-man's radio station. Depends on his choice results in competitions and ratings.

HF power amplifiers on tubes, transistor HF power amplifiers

An output amplifier (power amplifier - PA) is an amplifier loaded onto an antenna. The output amplifier consumes most of the power. The operation of the PA mainly determines the energy performance of the entire radio station, so the main requirement for the output stage is to obtain high energy performance. In addition, good filtering of higher harmonics is very important for the output amplifier.

A good modern HF power amplifier is a rather complex and labor-intensive device, as evidenced by world prices for branded PAs, at least in relation to the cost of middle-class transceivers produced by the same companies. This is explained, firstly, by the high cost of the lamps themselves used in the PA, and secondly, also by the high percentage of manual labor in their manufacture.

ACOM-1000

The ACOM 1000 HF power amplifier is one of the most worthy HF power amplifiers in the world. The output power of ACOM 1000 is at least 1000 W on all amateur radio bands from 160 to 6 meters.

Without antenna tuner

The amplifier functions as an antenna tuner with an SWR of up to 3:1, thus allowing you to change antennas faster and use them over a larger frequency band, saving tuning time.

One output tube 4CX800A (GU-74B)

The amplifier uses a high-performance metal-ceramic tetrode produced by the Svetlana plant with an anode dissipation power of 800 W (with forced air cooling and grid control).

Technical characteristics of the ACOM 1000 power amplifier:

• Frequency range: all amateur radio bands from 1.8 to 54 MHz; extensions and/or changes upon request.
• Output power: 1000 W peak (PEP) or push mode, no operating mode restrictions.
• Intermodulation distortion: better than 35 dB below peak rated power.
• Hum and Noise: Better than 40 dB below peak rated power.

Harmonic Suppression:

• 1.8 - 29.7 MHz - better than 50 dB below peak rated power.
• 50 – 54 MHz - better than 66 dB below peak rated power.

Input and output impedance:

• nominal: 50 ohms, unbalanced, UHF connectors (SO239);
• input circuit: wideband, SWR less than 1.3:1 in a continuous frequency band of 1.8-54 MHz (no need for tuning and switching);
• pass-through SWR less than 1.1:1 in the continuous frequency band 1.8-54 MHz;
• Output matching capabilities: better than 3:1 SWR or greater at reduced power levels.

• RF gain: 12.5 dB typical, frequency response less than 1 dB (with 50 - 60 W input signal at rated output power).
• Supply voltage: 170-264 V (200, 210, 220, 230 and 240 V taps, 100, 110 and 120 V taps on request, with tolerance +10% - 15%), 50-60 Hz, single phase, Consumption 2000 VA at full power.
• Meets the safety requirements of EEC countries and the requirements for electromagnetic compatibility parameters, as well as the rules of the US Federal Communications Commission (FCC) (the unit is installed on the 6, 10 and 12 m bands).
• Dimensions and weight (in working condition): 422x355x182 mm, 22 kg
• Requirements for environmental parameters during operation:
• temperature range: 0...+50°С;
• relative air humidity: up to 75% at a temperature of +35°C;
• altitude: up to 3000 m above sea level, without deterioration of technical parameters.

ACOM-1011

The ACOM 1011 power amplifier is developed on the basis of the well-known ACOM 1010.

The outstanding performance characteristics of the latter have been noted by many radio amateurs around the world.

At the WRTC Championship in Brazil, teams used the ACOM 1010 amplifier and it was recognized as the most optimal for both stationary use and DXpeditions.

The main differences between the two amplifiers:

• The ACOM 1011 uses two 4CX250B tubes, currently produced by many of the most renowned tube manufacturers, and provides the same power output as a single GU-74B tube.
• The lamp warm-up time has been reduced to 30 seconds.
• The tube panels are custom made by ACOM and designed specifically for installation in this amplifier.
• The ACOM 1011 uses a new fan designed and manufactured specifically for ACOM based on the well-known and proven fans used in the ACOM 1000 and ACOM 2000 models. It uses similar components, which provides better cooling and quieter operation of the amplifier overall compared to with ACOM 1010.
• ACOM 1011 has some differences both outside and inside. The more durable metal construction improves its performance during transport and DXpedition work.

ACOM-2000

Automatic power amplifier ACOM 2000A is an HF amplifier with the most advanced technical characteristics in the world of amplifiers manufactured for amateur radio applications. The ACOM 2000A is the first amateur radio power amplifier to combine a fully automated setup process with sophisticated digital control capabilities. The new amplifier has an improved design and produces maximum permitted power in all radiation modes and operates on all amateur radio HF bands.

Cutting-edge technology improves classic amplifier design

Fully automatic setup

The automatic tuning functions of the ACOM 2000A amplifier are a real breakthrough in the field of HF power amplifier design. There is no need to think about using an antenna tuner with an SWR of up to 3:1 (2:1 in the 160 meter range). The process of matching the actual characteristic impedance with the optimal lamp load is fully automated. This process lasts no more than one second and does not require much experience.

QSK – full duplex mode

Full duplex operation (QSK) is based on a built-in vacuum relay. The sequence of switching from transmitting to receiving mode is provided by a dedicated microprocessor.

Remote control

Only the remote control should be located near the operator. The amplifier itself can be placed up to 3 m (10 ft) away. GLE functions include: amplifier status on the LCD display, control of all functions, measurement and/or monitoring of the twenty most important parameters of the amplifier, operational technical information, troubleshooting suggestions, recording of the number of operating hours, password protection.

Protection

• Continuous monitoring and protection of such parameters and functions as:
• all lamp voltages and currents,
• supply voltages,
• overheat,
• pumping based on input signal,
• insufficient amount of cooling air,
• internal and external RF sparking (in amplifier, antenna switch, tuner or antennas),
• sequence of switching from transmit to receive T/R,
• switching the antenna relay during transmission,
• quality of matching with the antenna,
• reflected power level,
• saved data,
• inrush current of the supply voltage network,
• Lid lock for operator safety.

Technical characteristics of the ACOM 2000A power amplifier:

• Output power: 1500-2000 W in push mode or SSB mode - no time limit. Continuous radiation mode - 1500 W output power - no time limit when using an additional cooling fan.
• Frequency range: all amateur radio bands from 1.8 to 24.5 MHz. 28 MHz band only with modifications for licensed radio amateurs.
• Reranging/Tuning: Initial output matching occurs in less than 3 seconds (typically 0.5 seconds). The process of adjusting to previously agreed upon settings/band switching takes less than 0.2 seconds to move to another part of the same range, and less than 1 second when moving to another range.
• Non-volatile storage device (memory) for configuring up to 10 antennas per frequency segment.
• Drive signal power: typically 50 Watts with 1500 Watts output power.
• Input impedance: nominal 50 Ohm. SWR<1.5:1.
• Output tolerance: up to 3:1 VSWR (2:1 at 160 meters) at full output power before high VSWR protection circuit is activated. Higher SWR values ​​are matched at lower output power.
• Harmonic Content: At least 50 dB below peak at 1500 Watts.
• Intermodulation Interference: At least 35 dB below peak at 1500 Watts.
• T/R Switching and Keying: Vacuum Relay: Capable of Full Duplex (QSK) operation.
• Output tubes and circuits: tetrodes 4CX800A/GU74B (2 pcs.), resistive grid, PI-L output circuit with negative RF feedback. Adjustable screen grid voltage.
• Automatic Level Control (ALC): Negative grid voltage control, -11V maximum, rear panel adjustable.
• The remote control unit provides monitoring of all operating parameters of the amplifier.
• Protection: limiting the current of the control and screen grid, due to power surges (the possibility of smooth switching is provided), shutdown when the reflected power value is exceeded, when sparking in the RF circuit, access is password protected if necessary, correction of alternating switching between transmit and receive modes (T/R) , removal of lamp cooling air, blocking and grounding device for the high voltage circuit when opening the cover.
• Fault diagnosis: remote control display, plus indicators, plus information device "INFO Box" for the last 12 events. Computer interface (RS-232), plus remote telephone polling line function.
• Cooling: Full forced airflow inside the case. Rubber insulated fan.
• Transformer: 3.5 KVA with Unisil-Ha strip core.
• Power supply requirements: 100/120/200/220/240 Volts AC. 50-60 Hertz. 3500 VA, single phase, at full power.
• Overall dimensions: HF unit: length 440 mm, height 180 mm, depth 450 mm, remote control unit: length 135 mm, height 25 mm, depth 170 mm
• Transported in two cardboard boxes, total weight 36 kg.
• There are no controls on the HF unit, with the exception of the ON/OFF switch.

Alpha-9500

The Alpha-9500 is no ordinary linear amplifier, but the culmination of over 40 years of design and engineering.

Alpha-9500 is an advanced technology, auto-tuning linear amplifier easily provides 1500W of output power with a minimum input power of only 45W.

SPECIFICATIONS:

All amateur bands from 1.8 - 29.7 MHz

• Output power: 1500 W minimum, on all bands and types of radiation
• 3rd order IM:< -30 дБн
• SWR allowed: 3:1
• Power input: 45-60 W to achieve rated full power
• Lamp: one 3CX1500/8877 - high power and performance triode with a dissipation power of 1500 W provides the declared power in all frequency ranges, in all modes, in all duty cycles.
• Cooling: Forced air from two fans
• Antenna Outputs: Comes standard with 4 SO-239 connectors, but can be changed to N type on the rear panel by removing 4 screws.
• Antenna selection: internal antenna 4-port switch with 1 or 2 outputs per band
• Calibrated Wattmeter: The Bruene Wattmeter allows you to simultaneously measure forward and reverse power and display this information in an easy-to-read front panel bar graph. It also uses the information to simultaneously control the amplifier's gains.
• Protection mechanisms: high-voltage blocking and power supply blocking.
• Bypass Mode: There are two "ON" power switches on the front panel of the ALPHA-9500.
• "ON1" activates the Wattmeter and antenna switch without turning off the power to the amplifier itself, and sets the amplifier to bypass mode.
• The amplifier itself is turned on with the "ON2" button.
• Input: Comes standard with SO-239 BIRD connector, but can be changed to BIRD N type
• Tuning/switching ranges: Automatic, plus manual control
• Power: 100, 120, 200, 220, 240 VAC, 50/60 Hz, automatic selection. At 240 VAC, the amplifier draws up to 20 amps.
• Interface: serial port and USB. Full remote control function.
• Protection: Protection against all common faults.
• Display: The display shows histograms of power, SWR, grid current, plate current, plate voltage and gain - all at once. The digital instrument panel can display input power, plate current, plate voltage, grid current, SWR, filament voltage and PEP output.
• Tx/Rx switching: two Gigavac proprietary vacuum relays allow QSK to QRO operation.
• Output power: 1500 W.
• Weight: 95 lbs
• Dimensions: 17.5"W X 7.5"H X 19.75"D

Ameritron AL-1500

Ameritron AL-1500 is one of the most powerful linear amplifiers, covering all HF and WARC ranges.

It uses a manually tuned amplifier, which is designed around a single 3CX1500/8877 ceramic tube and has an efficiency of at least 62-65%.

With an input power of 65 W, it produces the legal maximum power with a large margin, up to 2500 watts.

The amplifier features a Hypersil ® transformer, dual backlit instruments, adjustable ALC, delay time adjustment, current protection and more.

Price (approximately in the Russian Federation) = $3650

Ameritron AL-572X

The Ameritron AL-572 amplifier is made using four 572B tubes using a common grid design. The Ameritron AL-572 amplifier uses tube capacitance neutralization, which improves performance and stability in the HF ranges. The lamps are installed vertically, which significantly reduces the risk of interelectrode short circuits

To match the input of the Ameritron AL-572 amplifier with the output of the transmitter, separate P-circuits are installed at the input for each of the operating ranges. The use of a tuned input equalizes the load on the output stage of the transceiver and allows you to get an SWR close to 1 on all bands. Additional adjustment of the circuits is possible through the holes in the rear panel of the amplifier.

The anode power supply is assembled using a voltage doubling transformer circuit and uses high-capacity electrolytic capacitors. The anode transformer is wound on a prefabricated steel core made of plates coated with high temperature resistant silicone coating, providing high power density with low weight. The anode no-load voltage is 2900 volts, at full load about 2500 volts. To reduce the temperature inside the Ameritron AL-572 case, a low-speed computer-type fan is used to circulate air at a low noise level.

Details of the Ameritron AL-572 output circuit (frameless coils made of thick wire, anode capacitor with ceramic insulators and a large gap between the plates, range switch on a ceramic dielectric) ensure reliable operation and high efficiency of the oscillatory system. The handles of variable capacitors are equipped with verniers with retardation and rotor position indication.

The Ameritron AL-572 amplifier also has an ALC system, a switch for operating and bypass modes, an indication of transmission operation and instruments for measuring the voltage of the anode power source / anode current and the value of the grid current. Both measuring instruments are backlit. For QSK operation, it is possible to install an additional QSK-5 module.

Price (approximately in the Russian Federation) = $2240

Specifications

• Peak output power: SSB 1300 Watts, CW 1000 Watts
• Excitation power from the transceiver 50-70 Watts
• Lamps: 4 572B lamps with neutralization in inclusion with a common grid
• Power supply: mains 220 volts
• Dimensions: 210x370x394 mm
• Weight: 18 kg
• Manufacture: USA

Ameritron AL-800X

Tube power amplifier for HF transceivers

Operating frequency range: from 1 to 30 MHz

Output power: 1250 Watts (peak)

Built on a 3CX800A7 tube

Price (approximately in the Russian Federation) = $2900

Ameritron AL-80BX

The Ameritron AL-80B linear power amplifier is made using a 3-500Z tube using a common grid design. The lamp is installed vertically, which significantly reduces the risk of interelectrode short circuits.

To match the input of the Ameritron AL-80B amplifier with the output of the transmitter, separate P-circuits are installed at the input for each of the operating ranges. The use of a tuned input equalizes the load on the output stage of the transceiver and allows you to get an SWR close to 1 on all bands. Additional adjustment of the circuits is possible through the holes in the rear panel of the amplifier.

The anode power supply of the Ameritron AL-80B amplifier is assembled using a transformer circuit with voltage doubling and uses high-capacity electrolytic capacitors. The anode transformer is wound on a prefabricated steel core made of plates coated with high temperature resistant silicone coating, providing high power density with low weight. The anode no-load voltage is 3100 volts, at full load about 2700 volts. To reduce the temperature inside the case, a low-speed computer-type fan is used, which ensures air circulation at a low noise level.

The details of the output circuit of the Ameritron AL-80B amplifier (frameless coils made of thick wire, an anode capacitor with ceramic insulators and a large gap between the plates, a range switch on a ceramic dielectric) ensure reliable operation and high efficiency of the oscillatory system. The handles of variable capacitors are equipped with verniers with retardation and rotor position indication.

The Ameritron AL-80B amplifier also has an ALC system, a switch for operating and bypass modes, an indication of transmission operation and instruments for measuring the voltage of the anode power supply/anode current and the magnitude of the grid current. For QSK operation, it is possible to install an additional QSK-5 module.

Price (approximately in the Russian Federation) = $1990

Specifications

• Operating ranges: 10-160 meters, including WARC
• Peak output power: SSB 1000 Watts, CW 800 Watts
• Excitation power from the transceiver 85-100 Watts
• Lamps: 3-500Z lamp with neutralization in inclusion with a common grid
• Input and output impedance: 50 ohms
• Power supply: mains 220 volts
• Dimensions: 210x370x394 mm
• Weight: 22 kg
• Manufacture: USA

Ameritron AL-811

The Ameritron AL-811 HX linear power amplifier is made using four 811A lamps (a complete analogue is the G-811 lamp) according to a circuit with a common grid. The lamps are installed vertically, which significantly reduces the risk of interelectrode short circuits.

To match the amplifier input with the transmitter output, separate P-circuits are installed at the input for each of the operating ranges. The use of a tuned input equalizes the load on the output stage of the transceiver and allows you to get an SWR close to 1 on all bands. Additional adjustment of the circuits is possible through the holes in the rear panel of the amplifier.

The anode power source is assembled using a transformer bridge circuit and uses high-capacity electrolytic capacitors. The anode transformer is wound on a prefabricated steel core made of plates with a high-temperature resistant silicone coating, providing high power density with low weight (8 kg). The anode no-load voltage is 1700 volts, at full load about 1500 volts. To reduce the temperature inside the case, a low-speed computer-type fan is used, providing air circulation at a low noise level.

The amplifier also has an ALC system, a switch for operating and bypass modes, an indication of transmission operation and instruments for measuring the voltage of the anode power source/anode current and the value of the grid current. For QSK operation, it is possible to install an additional QSK-5 module.

Price (approximately in the Russian Federation) = $1200

Specifications

• Peak output power - in SSB mode 800 Watt, in CW mode 600 Watt (excitation power from the transceiver 50-70 Watt)
• Input and output impedance - 50 Ohm
• Operating ranges - 10-160 meters, including WARC
• 4 811A lamps included with a common grid
• Adjustable ALC output
• Supply voltage 240 volts, commutable
• taps for mains power 100/110/120/210/220/230 volts
• Weight 15 kg

Ameritron AL-82X

The Ameritron AL-82X linear power amplifier is made using two 3-500Z tubes using a common grid design. The Ameritron AL-82 amplifier uses tube capacitance neutralization, which improves performance and stability in the HF ranges. The tubes in the Ameritron AL-82 amplifier are mounted vertically, which significantly reduces the risk of interelectrode short circuits.

To match the input of the Ameritron AL-82X amplifier with the output of the transmitter, separate P-circuits are installed at the input for each of the operating ranges. The use of a tuned input of the Ameritron AL-82 amplifier equalizes the load on the output stage of the transceiver and allows you to get an SWR close to 1 on all bands. Additional adjustment of the circuits is possible through the holes in the rear panel of the amplifier.

The anode power supply of the Ameritron AL-82 amplifier is assembled using a voltage-doubling transformer circuit and uses high-capacity electrolytic capacitors. The anode transformer is wound on a prefabricated steel core made of plates coated with high temperature resistant silicone coating, providing high power density with low weight. The anode no-load voltage is 3800 volts, at full load about 3300 volts. To reduce the temperature inside the Ameritron AL-82 amplifier, a low-speed computer-type fan is used to circulate air at a low noise level.

Details of the output circuit (frameless coils made of thick wire, an anode capacitor with ceramic insulators and a large gap between the plates, a range switch on a ceramic dielectric) ensure reliable operation and high efficiency of the oscillatory system. The handles of variable capacitors are equipped with verniers with retardation and rotor position indication.

The Ameritron AL-82X amplifier also has an ALC system, a switch for operating and bypass modes, an indication of transmission operation and instruments for measuring the voltage of the anode power source/anode current and the value of the grid current. Both measuring instruments are backlit. For QSK operation, it is possible to install an additional QSK-5 module.

Price (approximately in the Russian Federation) = $3000

Ameritron AL-82X Amplifier Specifications

• Operating ranges 10-160 meters, including WARC
• Peak output power: SSB 1800 Watts, CW 1500 Watts
• Excitation power from the transceiver 100 Watt
• Lamps: 2 lamps 3-500Z lamps with neutralization in inclusion with a common grid
• Input and output impedance 50 Ohm
• Power supply 220 volts
• Dimensions 250x432x470 mm
• Weight 35 kg
• Made in USA

Ameritron ALS-1300

Ameritron offers its new solid-state amplifier ALS-1300.

The amplifier output power is 1200W in the frequency range 1.5 - 22 MHz.

The amplifier does not require time to rebuild; 8 pcs MRF-150 FETs are used as output transistors.

The amplifier uses a fan whose rotation speed is controlled by temperature sensors to ensure minimal noise.

The ALS-500RC remote control can be used with the ALS-1300 amplifier

Ameritron ALS-500M

The amplifier uses four powerful 2SC2879 bipolar transistors

The amplifier is made without the use of vacuum tubes, so it does not require preheating

The amplifier does not need to be adjusted. Switching ranges from 1.5 to 29 MHz is carried out with one knob

The amplifier monitors the load resistance and if it deviates more than the permissible norm, “bypass” is activated

The amplifier has a built-in current consumption indicator that allows you to monitor the collector current of the output transistors

To bypass the amplifier, you do not need to disconnect it. You just need to switch it to the “off” position

The weight of the amplifier is only 3.9 kg with dimensions of 360x90x230 mm

When operating the amplifier in stationary mode, it is recommended to use a power source with an output voltage of 13.8 V and an operating current of at least 80 A.

Price (approximately in the Russian Federation) = $1050

Technical characteristics of the ASL-500M power amplifier:

• Frequency range: 1.5 - 30 MHz
• Output power: 500 W peak (PEP) or 400 W in CW mode
• Drive signal power: typically 60-70 W
• Supply voltage: 13.8 V, consumption 80 A
• Harmonic Rejection: 1.8 – 8 MHz – better than 60 dB below peak rated power, 9 – 30 MHz – better than 70 dB below peak rated power
• When operating the amplifier in stationary mode, it is recommended to use a power source with a maximum output current of at least 80A.

Ameritron ALS-600

No setup, no fuss, no worry - just plug and play

Includes 600 W output power, continuous frequency range 1.5-22 MHz, instantaneous band switching, no warm-up time, no child-hazardous lamps, maximum SWR protection, completely silent, very compact.

The revolutionary AMERITRON ALS-600 amplifier is the only linear amplifier in ham radio that uses four reliable RF power TMOS FETs - delivering unsurpassed solid-state quality and requiring no tuning. Price includes non-tuned FET amplifier and 120/220 VAC, 50/60 Hz power supply for home use.

You get instant range switching, no setup required, no warm-up time, no fuss! The ALS-600 amplifier provides a maximum 600 W envelope output power and 500 W CW power over a continuous frequency range of 1.5 to 22 MHz

The ALS-600 amplifier is completely silent. The low-speed, low-volume fan is so silent that it is difficult to detect its presence, unlike the noisy blowers found in other amplifiers. The ALS-600 amplifier has small dimensions: 152x241x305 mm - it takes up less space than your radio! Weighs only 5.7 kg.

The two-pointer SWR and power meter with backlight allows you to read the values ​​of SWR, maximum power of the incident and reflected waves simultaneously. The Operate/Standby switch allows you to operate in low power mode, but you can instantly switch to full power mode if needed.

You get the ability to control the ALC system from the front panel! This unique AMERITRON system allows you to adjust the power output on a convenient front panel indicator. Additionally, you get LED indicators for transmit, ALC and SWR on the front panel. The 12 VDC output jack allows you to power low-current accessories. Enjoy 600 watts of non-tuning solid state amplifier power. A pair of RJ45 remote control interface jacks on this amplifier allow you to control the ALS-600 amplifier either manually using the ALS-500RC compact remote control unit, or automatically using the ARI-500 automatic band selector. The Automatic Band Switch reads band data from your transceiver and automatically changes the ALS-600 amplifier's bands when the bands on the transceiver change.

Price (approximately in the Russian Federation) = $1780

Expert 1K-FA

Fully automatic 1KW transistor linear amplifier.

Built-in power supply and automatic antenna tuner. Dimensions: 28x32x14 cm (including connection connectors).

Weight about 20 kg.

The Expert 1K-FA amplifier uses two processors, one of which is designed to automatically adjust the output P-circuit. (System S.A.T.s) More than 13,000 software elements provide a unique set of technical characteristics not found in other models.

Possibility of easy connection to all models of Icom, Yaesu, Kenwood transceivers, automatic antenna tuner, control of antenna characteristics, immediate broadcasting. Similar results when working with models from other companies and homemade equipment. The operator's functions are limited to rotating the frequency control knob in the transceiver.

From 1.8 MHz to 50 MHz including WARC bands. Fully transistor design. 1 kW PEP in SSB mode (nameplate value). 900 W in CW mode (rated value) 700 W PEP in the 50 MHz band (rated value).

Automatic selection of full/half power by operator command in CW and SSB modes, for digital types of operation and providing automatic amplifier protection. Does not require time to warm up.

The amplification elements are not subject to aging (CMOS transistors are used). Built-in automatic antenna tuner. It is possible to match antennas up to SWR values ​​of 3:1 on HF, and 2.5:1 on 6 meters. Switching up to 4 antennas (SO239 connectors). Switching bands, antennas and all adjustments are carried out in 10 milliseconds. When working only from the transceiver, adjustments, switching of bands and antennas are carried out in the “standby” mode. Availability of two entrances. SO 239 connectors are used.

Drive power 20 W.

Continuous monitoring of temperature, overcurrent and voltage, SWR level, reflected power level, maximum RF tuner voltage, input power “pumping”, imbalance of amplifier stages. Full duplex mode (QSK). Low noise operation. The amplifier and transceiver can be turned on and off independently. The large LCD display displays a large amount of information.

Connection via RS 232 port for control via PC. For ease of carrying, the amplifier fits into a small bag. Possible to work on field days and DX expeditions.

BLA 1000

RM BLA-1000 is a new transistor amplifier, with an output power of up to 1000W, which implements all the most advanced achievements in amplifier design. The output stage of the amplifier is made of two super-power field-effect (MOSFET) transistors MRF-157. A 2-cycle bridge amplification circuit (Push-Pull type), operating in AB2 mode, provides high gain and good amplifier efficiency while maintaining high linearity.

For the convenience of covering all operating ranges, there are 2 antenna ports on the rear panel of the amplifier. For example, you can connect high-frequency range antennas to one port, and low-frequency range antennas to the second.

To control the linearity of the amplifier, there is an ALC input on the rear panel. The possibility of both automatic control of the ALC level and from the transceiver has been implemented. ALC parameters can be adjusted manually using 2 resistors. The release time of the transmit relay (RX-delay) can be adjusted in the range of 0...2.5 seconds in steps of 10 ms.

Switching the “Receive/Transmit” mode can be done either from the transceiver or automatically (Int. VOX). For this purpose, there is an RC connector - “PTT” on the rear panel of the amplifier.

The amplifier is powered by its built-in switching power supply. The amplifier's high output power is obtained by feeding the transistors with high voltage - 48 Volts. In this case, the current consumption at the signal peak can reach 50 Amperes.

One of the interesting features of this amplifier is its ability to operate in fully automatic mode. In this mode, you do not need to switch not only the “Receive/Transmit” mode, but also the operating range of the amplifier. The frequency meter built into the microprocessor will automatically determine the transmission frequency and select the desired low-pass filter. This function will be especially useful for using the amplifier in “unattended areas” or “enclosed spaces” of industrial radio communication structures.

Price (approximately in the Russian Federation) = $4590

Technical characteristics of the power amplifier RM BLA-1000

• Frequency range 1.5-30 and 48-55 MHz
• Supply voltage 220-240 Volts; 15.5 A
• Input power 10-100 Watt
• Output power 1000 Watt
• Impedance Input/Output 50 Ohm
• Overall dimensions 495 x 230 x 462 mm
• Weight 30 kg

BLA 350

New, inexpensive amplifier RM BLA-350. An ideal solution for a beginner or intermediate radio amateur who has decided to amplify the signal of his transceiver or protect the output stage for little money. Due to the built-in powerful power supply, the amplifier takes up little space on the table.

The output stage of the amplifier is made of two powerful field-effect (MOSFET) transistors SD2941. A 2-cycle bridge amplification circuit (Push-Pull type), operating in AB2 mode, provides high gain and good amplifier efficiency while maintaining high linearity. Additional purity of the output signal is provided by 7 low-pass filters of the 7th order, which is an important parameter for basic amplifiers.

Thanks to microprocessor control, the control of the amplifier operating modes is fully automated and temperature, SWR and input power control is implemented. Flexible configuration of protection and alarm parameters is possible when threshold values ​​are exceeded.

Switching of the “Reception/Transmission” mode can be controlled either from the transceiver or automatically (Int. VOX). For this purpose, there is an RC connector - “PTT” on the rear panel of the amplifier.

One of the interesting features of this amplifier is its ability to operate in fully automatic mode. In this mode, you do not need to switch not only the “Reception/Transmission” mode, but also the operating range of the amplifier. The frequency meter built into the microprocessor will automatically determine the transmission frequency and select the desired low-pass filter. This function will be especially useful for using the amplifier in “unattended areas” or “enclosed spaces” of industrial radio communication structures.

Price (approximately in the Russian Federation) = $1090

Technical characteristics of the power amplifier RM BLA-350

• Frequency range 1.5-30 MHz (Including WARC bands)
• Modulation types AM/FM/SSB/CW/DIGI
• Supply voltage 220-240 Volts; 8 A
• Input power 1-10 Watt
• Output power 350 Watt
• Impedance Input/Output 50 Ohm
• Overall dimensions 155 x 355 x 270 mm
• Weight 13 kg

Elecraft KPA-500

The power amplifier is designed to operate on all amateur radio HF bands from 160 to 6 meters (including WARC bands) in all operating modes. The KPA-500 automatically tunes to your transceiver's frequency.

An all-solid-state amplifier with a power of 500 W on powerful FET transistors, has the same dimensions as the Elecraft K3 transceiver and fits perfectly into the line of devices of this company.

The amplifier has an alphanumeric display, a bright LED indicator and a reliable, powerful built-in power supply. The device works with any transceiver that uses a grounded PTT output. When pumping or increasing the SWR, the power is automatically reduced by 2.5 dB, and when the problem is eliminated, it returns to the nominal value.

The amplifier provides ultra-fast, silent QSK using a high-power PIN diode switch. The device has a six-speed temperature-controlled fan. When using the optional KPAK3AUX cable, enhanced integration with the K3 transceiver is provided:

• manual control buttons on the KRA500 panel control the ranges and drive level on the K3;
• data on switching ranges is transmitted from K3 before the start of transmission;
• PTT is transmitted via cable, no separate control is required;
• K3 detects the current state of the amplifier and adjusts the drive level according to one of two memory states on each band.

When the Internet is connected, the presence of new firmware versions is automatically detected from the company server via the RS232 port.

HLA-150

Price (approximately in the Russian Federation) = $520

• Input power: 1 - 8 W.
• Output Power: 150W CW or 200W PEP in SSB.
• Supply voltage: 13.8 V.
• Maximum current consumption: up to 24 A.
• Dimensions: 170x225x62 mm, weight 1.8 kg.

HLA-300

The amplifier has microprocessor control, a frequency range of 1.5-30 MHz, LED indicators of output power and operating range, automatic TX/RX switching. Band switching can be done automatically or manually. The amplifier has band filters on the output that are switched manually when the range changes.

In the event of a malfunction of the amplifier or antenna-feeder system, or an increase in the level of spurious emissions, the protection system will automatically turn off the amplifier and/or connect the transceiver directly to the antenna (“bypass” mode). To manually enable the bypass mode, simply turn off the power to the amplifier.

Input power 5 - 15 W.

Output power 300 W CW or 400 W PEP in SSB.

Supply voltage 13.8 V.

Maximum current consumption up to 45 A.

Dimensions 450x190x80 mm, weight 3 kg. Price (approximately in the Russian Federation) = $750

OM Power OM 1500

Linear power amplifier for operation on all amateur bands from 1.8 to 29 MHz (including WARC bands) + 50 MHz with all types of modulation. Equipped with a ceramic tetrode GS-23B.

Specifications:

Operating frequency range: amateur bands from 1.8 to 29.7 MHz, including WARC bands + 50 MHz.

Output Power: 1500+ Watts in SSB and CW modes on HF bands, 1000 Watts in SSB and CW modes on 50 MHz, 1000+ Watts in RTTY modes

Input Power: Typical 40 to 60 Watts for full power output.

Input Impedance: 50 ohms at SWR< 1.5: 1

Gain: 14 dB, Output Impedance: 50 Ohms, Maximum SWR: 2:1

SWR boost protection: automatic switch to STANDBY mode when reflected power exceeds 250 W

Intermodulation distortion: 32 dB of rated output power.

Harmonic Suppression:< -50 дБ относительно мощности несущей.

Lamp: GS-23B ceramic tetrode. Cooling: Centrifugal fan.

Power supply: 1 x 210, 220, 230 V - 50 Hz. Transformers: 1 toroidal transformer 2.3 KVA

Peculiarities:

Antenna switch for three antennas

Memory for errors and warnings - easy operation

Automatic anode current adjustment (BIAS) - no adjustment required after lamp replacement

Automatic adjustment of fan speed depending on temperature

Full QSK with silent relay

Smallest and lightest 1500W amplifier on the market

Dimensions (WxHxD): 390 x 195 x 370 mm, Weight: 22 kg

OM Power OM 2500 HF

The Russian-made GU84b tetrode is used to obtain an output power of up to 2700 Watts.

The amplifier uses a GU84B tetrode in a circuit with a grounded cathode (the input signal is fed to the control grid). The amplifier exhibits excellent linearity between the control grid bias voltage and the screen grid voltage. The input signal is fed to the control grid using a wideband transformer with an input impedance of 50 ohms. This input circuit provides an acceptable SWR value (less than 1.5:1) on all HF bands.

The output stage of the amplifier is a Pi-L circuit. The variable capacitor on ceramic insulators for circuit tuning and load matching is divided into two parts and designed specifically for this amplifier. This allows you to fine-tune the amplifier and easily return to previously tuned positions after changing the range.

The high anode voltage consists of 8 voltage sources of 300V/2A each. Each source has its own rectifier and filter. Safety resistors are used in the anode voltage circuit to protect the amplifier from overload. The grid voltage is stabilized by a circuit of IRF830 MOSFETs and is 360V/100mA. The control grid voltage -120V is stabilized by zener diodes.

Main technical characteristics of the power amplifier OM2500 HF

• Output Power: 2500 Watts in CW and SSB modes, 2000 Watts in RTTY, AM and FM modes
• < 2.0: 1 входное - 50 Ом при КСВ < 1,5:1
• RF gain: no less than 16 dB
• Protection units: when SWR, anode and grid currents increase, or when the amplifier is configured incorrectly, providing a soft start to protect fuses, blocking the switching on of dangerous voltages when the amplifier covers are removed
• Dimensions and weight (in working condition): 485x200x455 mm, 38 kg

OM Power OM2000 HF

The power amplifier is designed to operate on all HF bands from 1.8 to 29 MHz (including WARC bands) in all operating modes.

High frequency block:

The amplifier uses a GU-77B tetrode according to a circuit with a grounded cathode with excitation supplied to the control grid. The amplifier has excellent linearity because the control grid bias and screen grid voltage are well stabilized. The input signal is fed to the control grid through a broadband matching device with an input impedance of 50 Ohms. This solution ensures matching of the amplifier input with an SWR of no worse than 1.5:1 on any HF band.

Power supply

Using a unit made of relays and powerful resistors, a powerful rectifier is soft-started. The high-voltage unit is composed of eight sections providing 350 volts at a current of 2 amperes, each of which has its own rectifier and filter. Safety resistors are installed in the anode voltage circuit to protect the amplifier from overload.

Amplifier protection

Main technical characteristics of the OM2000 HF power amplifier

• Frequency range: all amateur radio bands from 1.8 to 29.7 MHz;
• Output power, no less: 2000 W in CW and SSB modes, 1500 W in RTTY, AM and FM modes
• Intermodulation distortion: no more than -32 dB from peak rated power.
• Harmonic suppression: greater than 50 dB peak rated power.
• Characteristic impedance: output - 50 Ohm, for asymmetric load, at SWR< 2.0: 1 входное - 50 Ом при КСВ < 1,5:1
• RF gain: no less than 17 dB
• Supply voltage: 230V – 50Hz, one or two phases
• Transformers: 2 toroidal transformers, 2KVA each
• Dimensions and weight (in working condition): 485x200x455 mm, 37 kg

OM Power OM2500 A

The power amplifier is designed to operate on all HF bands from 1.8 to 29 MHz (including WARC bands) in all operating modes. The OM2500 A automatically tunes to the transceiver frequency.

High frequency block

The amplifier uses a GU-84B tetrode according to a circuit with a grounded cathode with excitation supplied to the control grid. The amplifier has excellent linearity because the control grid bias and screen grid voltage are well stabilized. The input signal is fed to the control grid through a broadband matching device with an input impedance of 50 Ohms. This solution ensures matching of the amplifier input with an SWR of no worse than 1.5:1 on any HF band.

The amplifier output has a Pi-L circuit enabled. Each of the variable capacitors, designed to adjust the circuit and load, is made of ceramic insulators and is divided into two sections. This solution allows you to more accurately tune the amplifier and easily return to the previous settings after changing the range.

Power supply

The amplifier is powered by two two-kilowatt toroidal transformers.

Using a unit made of relays and powerful resistors, a powerful rectifier is soft-started. The high-voltage unit is composed of eight sections providing 420 volts at a current of 2 amperes, each of which has its own rectifier and filter. Safety resistors are installed in the anode voltage circuit to protect the amplifier from overload.

The voltage for the screen grid is provided by a parallel stabilizer assembled on high-voltage transistors of the BU508 type, which provides a voltage of 360 volts at a current of up to 100 mA. The bias for the control grid (-120 volts) is also stabilized.

Amplifier protection

The device provides continuous monitoring and protection of all circuits in case of disturbances in the operation of the amplifier. The protection unit is located on the control board installed in the subpanel.

Main technical characteristics of the power amplifier OM2500 A

• Frequency range: all amateur radio bands from 1.8 to 29.7 MHz;
• Output power, no less: 2500 W in CW and SSB modes, 2000 W in RTTY, AM and FM modes
• Intermodulation distortion: no more than -32 dB from peak rated power.
• Harmonic suppression: greater than 50 dB peak rated power.
• Characteristic impedance: output - 50 Ohm, for asymmetric load, at SWR< 2.0: 1, входное - 50 Ом при КСВ < 1,5:1
• RF gain: no less than 17 dB
• Manual or automatic setting
• Tuning speed on the same range:< 0.5 сек.
• Tuning speed when tuning to another range:< 3 сек.
• Supply voltage: 230V – 50Hz, one or two phases. Transformers: 2 toroidal transformers, 2KVA each
• Protection units: if SWR, anode and grid currents increase, if the amplifier is configured incorrectly, providing a soft start to protect fuses, blocking the switching on of dangerous voltages when the amplifier covers are removed
• Dimensions and weight (in working condition): 485x200x455 mm, 40 kg

OM Power OM3500 HF

The OM3500 HF power amplifier is designed to operate on all HF bands from 1.8 to 29 MHz (including WARC bands) in all operating modes. The amplifier has a GU78B ceramic tetrode.

The amplifier uses a GU78B tetrode in a circuit with a grounded cathode (the input signal is fed to the control grid). The amplifier exhibits excellent linearity between the control grid bias voltage and the screen grid voltage. The input signal is fed to the control grid using a wideband transformer with an input impedance of 50 ohms. This input circuit provides an acceptable SWR value (less than 1.5:1) on all HF bands. The output stage of the amplifier is a Pi-L circuit. The variable capacitor on ceramic insulators for circuit tuning and load matching is divided into two parts and designed specifically for this amplifier. This allows you to fine-tune the amplifier and easily return to previously tuned positions after changing the range.

The amplifier's power supply consists of two 2KVA toroidal transformers. The soft start mode occurs using relays and resistors.

Amplifier protection:

Constant monitoring and protection of anode and grid voltages and currents is carried out in case of incorrect amplifier settings, a soft start mode is implemented to protect fuses.

Technical characteristics of the power amplifier OM3500 HF:

• Frequency range: all amateur radio bands from 1.8 to 29.7 MHz;
• Output Power: 3500 Watts in CW and SSB modes, 3000 Watts in RTTY, AM and FM modes
• Intermodulation distortion: better than 36 dB below peak rated power.
• Harmonic Rejection: Better than 55 dB below peak rated power.
• Characteristic impedance: output - 50 Ohms, for asymmetric load, input - 50 Ohms at SWR< 1,5:1
• RF Gain: Typical 17 dB
• Supply voltage: 2 x 230V – 50Hz, one or two phases
• Transformers: 2 toroidal transformers, 2.5 KVA each
• Dimensions and weight (in working condition): 485x200x455 mm, 43 kg

RM KL500

Amplifier RM KL500 HF range (3-30) MHz, input power 1-15 W, output 300 W with electronic switching technology and polarity reversal protection. It has six output power levels and a 26 dB antenna preamplifier.

Frequency: HF

Voltage: 12-14 Volts

Current consumption: 10-34 Amps

In. power: 1-15 W, SSB 2-30 W

Exit Power: 300W Max (FM) / 600W Max (SSB-CW)

Modulation: AM-FM-SSB-CW

Six power levels

Fuses: 3×12 A

Size: 170x295x62 mm

Weight: 1.6 kg Price (approximately in the Russian Federation) = $340

YAESU VL-2000

Great power combined with high reliability.

8 massive CMOS field-effect transistors of the VRF2933 type, connected in a push-pull circuit, provide the necessary output power in the range from 160 to 6 m. Two large fans with a continuous rotation speed control system effectively cool the PA and low-pass filter unit, providing years of reliable and silent operation .

Two large pointer instruments.

The left instrument shows the output power or SWR. Right – current consumption and supply voltage.

The monitoring system provides reliable and quick troubleshooting in the system.

In high-power devices, mains voltage fluctuations, temperature violations, high SWR levels, and exceeding the level of the RF drive signal at the input are monitored.

The built-in automatic high-speed antenna tuner matches your antenna to an SWR level of 1.5 or better in less than 3 seconds (according to the passport).

Two input and four output connectors allow integrated selection of the transmitter and the required antenna.

For example, two input connectors allow you to connect an HF transceiver to the first (INPUT 1), and a 6 m range transceiver to the second (INPUT 2). In this case, the output connectors can be connected to various antenna switching devices available at the station. Automatic selection of the required antenna can be performed for the transmitter connected to input 1 (INPUT 1), often eliminating the need for additional antenna switches. When the “DIRECT” toggle switch located on the rear panel is turned on, the amplified signal from input 2 (INPUT 2) is fed directly to the “ANT DIRECT” connector, bypassing the output switching system. In addition, the VL-2000 PA can be used in the SO2R system.

Automatic range switching for quick transitions.

Most modern Yaesu transceivers allow you to exchange data about the current range between the transceiver and the VL-2000 PA, which allows you to automatically change the range in the PA when you change the latter in the transceiver. To automatically change the range when using other types of transmitters, the VL-2000 PA has an automatic range detection function using a built-in frequency meter, which ensures an immediate change of range the first time an RF signal is applied to the PA input.

Specifications

• Range: 1.8-30; 50-54 MHz
• Antenna switch: ANT 1-ANT 4, ANT DIRECT
• Power: (1.8-30 MHz) 1.5 KW, (50-54 MHz) 1.0 KW
• Consumption: 63 A
• Supply voltage 48 V
• Types of work: SSB, CW, AM, FM, RTTY
• Range switching: manual/automatic
• Output transistor: VRF2933
• Output stage operating mode: Class-AB, Push-pull, Power Combine
• Spurious emissions: -60 dB
• Input power: 100 to 200 W
• Temperature: -10 +40 C
• Dimensions 482x177x508 mm, Weight: 24.5 kg
• Power supply: Output voltages: +48 V, +12 V, -12 V. Output current: +48 V 63 A, +12 V 5.5 A, -12 V 1A,
• Dimensions: 482x177x508 mm. Weight: 19 kg

tagPlaceholder Tags:

Many shortwave operators are convinced that everything is known about tube amplifiers. And even more... Maybe. But the number of low-quality signals on the air is not decreasing. Quite the contrary. And the saddest thing is that all this is happening against the backdrop of an increase in the number of industrial imported transceivers in use, the transmitter parameters of which are quite high and meet the requirements of the FCC (American Federal Communications Commission). However, some of my colleagues on the air, who have come to terms with the fact that you can’t make the FT 1000 “on the knee” and use RAs designed according to the canons of thirty years ago (GU29 + three GU50s), etc., are still confident that according to RA “we ahead of the rest." Let me note that “they are there, abroad,” not only buying, but also constructing RAs that are worthy of attention and repetition.

As you know, KB power amplifiers use circuits with a common grid (OC) and a common cathode (CC). The output stage with OS is almost a standard for radio amateurs in the CIS. Any lamps are used here - both those specially designed to work in a circuit with OS, and lamps for linear amplification in circuits with OK. Apparently, this can be explained by the following reasons:
- the circuit with OS is theoretically not prone to self-excitation, because the grid is grounded either by HF or galvanically;
- in the circuit with feedback, linearity is 6 dB higher due to negative current feedback;
- RA with OS provide higher energy levels than RA with OK.

Unfortunately, what is good in theory is not always good in practice. When using tetrodes and pentodes with a high slope of the current-voltage characteristic, the third grid or beam-forming plates of which are not connected to the cathode, the RA with OS can self-excite. If installation is unsuccessful, low-quality components (especially capacitors) and poor matching with the transceiver, conditions for phase and amplitude balance are easily created to obtain a classic self-oscillator on HF or VHF using a circuit with OS. In general, matching a transceiver with an RA according to the OS scheme is not as simple as it is sometimes written. Often cited figures, such as 75 ohms for four G811s, are only theoretically correct. The input impedance of the PA with feedback depends on the excitation power, anode current, P-circuit settings, etc. Changing any of these parameters, for example increasing the SWR of the antenna at the edge of the range, causes mismatch at the input of the stage. But that's not all. If a tuned circuit is not used at the input of the PA with OS (and this is a common occurrence in homemade amplifiers), then the excitation voltage becomes asymmetrical, because The current from the exciter flows only during the negative half-cycles of the input voltage, and this increases the level of distortion. Thus, it is possible that the above factors will negate the advantages of the OS scheme. But, nevertheless, RA with OS are popular. Why?

In my opinion, due to excellent energy performance: when it is necessary to “pump up power”, there is no price for a circuit with OS. In this case, the linearity of the amplifier is the last thing people think about, referring to what is firmly understood - “the distortions introduced by the cascade depend little on the choice of the operating point on the characteristic.” For example, a GU74B lamp designed for linear amplification of single-sideband signals in a typical connection in a circuit with OK should have a quiescent current of about 200 mA, and it is unlikely that it will be possible to obtain an output power of more than 750 W (at Ua = 2500 V) without risking the longevity of the lamp, t .To. the power dissipation at the anode will be limiting. It’s another matter if the GU74B is turned on with the OS - the quiescent current can be set to less than 50 mA, and an output power of 1 kW can be obtained. It was not possible to find information about measuring the linearity of such RAs, and arguments like “many QSOs were conducted on this amplifier, and correspondents invariably noted the high quality of the signal” are subjective and therefore unconvincing. Power of more than 1 kW in the above example is provided by the popular industrial ALPHA/POWER ETO 91B, using a pair of GU74B lamps with OK in the operating mode recommended by the manufacturer with known intermodulation characteristics. Apparently, the developers of this amplifier were concerned not only with economic considerations (another lamp increases the cost and complexity of the design), but also with the compliance of the PA parameters with the standards and requirements of the FCC.

The advantage of RA with OS is the absence of the need to stabilize the voltages of the screen and control grids. This is true only for a circuit in which the specified grids are directly connected to a common wire. Such inclusion of modern tetrodes can hardly be considered correct - not only is there no data on the linearity of the cascade in this mode, but also the power dissipation on the grids, as a rule, exceeds the permissible one. The excitation power for such a circuit is about 100 W, and this causes increased heating of the transceiver, for example, during intensive work on a general call. In addition, with a long connecting cable, it is necessary to use a switched P-circuit at the amplifier input in order to avoid high SWR values ​​and related problems.

The disadvantages of circuits with OK include the need to stabilize the voltages of the screen and control grids; however, in modern tetrodes in AB1 mode, the power consumed by these circuits is small (20...40 W), and the voltage stabilizers on currently available high-voltage transistors are quite simple. If the power transformer does not have the necessary voltages, you can use suitable low-power transformers by connecting them the other way around - with the secondary winding to a filament voltage of 6.3 or 12.6 V. Another disadvantage of the OK circuit is the high power dissipation at the anode during transmission pauses. One of the possible ways to reduce it is shown in Fig. 1 (simplified diagram from).

The excitation voltage is supplied through a capacitive divider to the full-wave rectifier VD1, VD2 and then to the comparator DA1. Triggering of the comparator transfers the lamp from the closed state to the operating mode. During transmission pauses, there is no excitation voltage, the lamp is locked, and the power dissipated at the anode is negligible.

In my opinion, RA with OS can be used on KB with outdated lamps - to reduce the cost of the design, or with lamps specially designed to work in such a connection. The use of a tuned LC circuit of low quality factor or a P-circuit at the input is mandatory. This is especially true for transceivers with wideband transistor output stages, the normal operation of which is possible only with a matched load. Of course, if the output stage of the transceiver has a customizable P-circuit or antenna tuner, and the length of the connecting cable does not exceed 1.5 m (i.e., it represents a capacitance for the frequency range used), such a circuit can be considered as an input for the PA. But in any case, the use of a P-circuit at the RA input significantly reduces the likelihood of self-excitation on VHF. By the way, this is exactly how the vast majority of PAs with OS described in foreign literature and produced by industry for shortwave frequencies are implemented. For radio amateurs who are planning to create an RA with a power of 500 W or more, it is recommended to use lamps specially designed for linear amplification of radio frequency signals in a circuit with OK. This recommendation becomes especially relevant when using expensive “branded” transceivers - in RA with OS, during self-excitation, there is significant power of RF or microwave oscillations at the input, which can lead to failure of either the output stage or the input circuits of the transceiver (depending on switching of the RX - TX circuit at the moment of self-excitation). Alas, this is not the author’s fantasy, but real cases from practice.

And one more problem cannot be ignored when considering tube RAs - with the light hand of V. Zhalnerauskas and V. Drozdov, schemes for constructing the transmitting part of the transceiver have become popular, when, after a bandpass filter, linear amplification of the radio frequency signal by transistor stages without intermediate filtering is used to excite the tube amplifier. Structurally, the transceiver is simplified, but the price of such simplicity is an increased content of spurious emissions if such circuits are not carefully configured.

The situation gets even worse when the output power of the transceiver is not enough to “drive”, for example in the case of the GU74B with OK with a wideband input circuit on a 1:4 transformer. The required gain is usually achieved by an additional broadband stage. If a low IF is used, and after a two- or three-loop DFT, the transmitting path has a gain of 40...60 dB in power, and the P-loop is the only selective circuit of this path, then sufficient suppression of spurious emissions is not ensured. The effects can be heard on the amateur bands every day, such as second harmonics almost equal in power to the main signal. Listen, for example, to the 3680...3860 kHz section, and you will almost certainly hear second harmonic signals from SSB stations on the 160-meter range. The RA itself also has a certain nonlinearity, so even when a spectrally pure radio frequency signal is supplied to it, harmonics are inevitably present at the output. A single P-circuit can be recommended for output power up to 1 kW. At higher power, foreign amateur and industrial PAs use the P-L circuit shown in Fig. 1 - its filtration coefficient is twice as high.

Let us now consider circuit solutions that demonstrate a rather demanding approach to the design of RA.

The publication introduces us to the American version of the homemade RA on the GU74B. George T. Daughters, AB6YL, having decided to remake the Dentron MLA2500 industrial amplifier, originally built on triodes according to the OS circuit, opted for the GU74B lamp (American designation - 4СХ800А). For this project, he considered it optimal to use the mode of supplying the excitation signal to the control grid, where the input power is dissipated by a fifty-ohm resistor between the grid and the common wire. This eliminated the need for customized input circuits and easily provided broadband. The low impedance of the control grid circuit helps avoid self-excitation and provides the transceiver's output stage with a stable resistive load with low SWR. In addition, the very popular commercial amplifier ALPHA/POWER 91B with an output power of 1500 W uses a pair of 4CX800A in this connection - this is an already proven circuit!

The amplifier circuit is shown in Fig. 2.

The large input capacitance of the 4CX800A (about 50 pF) requires the use of inductive compensation, especially in high frequency ranges. Wirewound resistor R1B 6 W/6 Ohm provides the necessary inductance and, together with non-inductive R1A and R1C, complements the load resistance to the required 50 Ohm/50 W. According to AB6YL measurements, at frequencies below 35 MHz the input SWR is less than 1.1.

The energy performance of the amplifier can be improved by connecting a non-inductive resistor R2 with a resistance of up to 30 Ohms between the cathode and the common wire. This resistor provides negative feedback, which reduces the quiescent current and slightly improves linearity; the level of fifth-order components decreases by approximately 3 dB.

The parameters of the P-circuit are not given, because Components from Dentron - MLA2500 were used.

The 4СХ800А filament must be turned on at least 2.5 minutes before the excitation and supply voltages are applied.

Specifications for 4СХ800А/ГУ74Б, supplied to the American market, recommend a bias voltage on the control grid of about -56 V with a screen voltage of +350 V. The control grid power supply consists of a low-power transformer T2, connected in reverse - to the secondary winding, used as the primary, A voltage of 6.3 V is supplied from the main transformer T1, which provides about 60 V AC voltage. At the output of the parametric stabilizer VD9, R12 there is a voltage of -56 V. Any control grid current causes nonlinear distortion leading to splatter. The grid current detector is assembled on an operational amplifier DA1, connected according to a comparator circuit. When the grid current exceeds a few milliamps, the voltage drop across R16 increases, causing the comparator to operate and the red LED to glow.

The screen grid is powered by a voltage stabilizer (VT1, VT2, VD7) with protection against excess current consumption. Relay contacts K2 switch the screen grid between the common wire (via R13) in receive mode and +350 V in transmit mode. Resistor R9 prevents voltage surges when switching the relay. The screen grid current is indicated by the PA1 pointer device, because For tetrodes, the screen grid current is a better indicator of resonance and tuning than the anode current. In transmit mode, the anode quiescent current should be 150...200 mA, while the screen grid current is about -5 mA (if a device without a zero in the middle is used, the arrow will move to the left all the way). The amplifier operates in linear mode and does not need ALC (as long as there is no control grid current) with an anode current of 550...600 mA and a screen grid current of approximately 25 mA. If the screen grid current at resonance exceeds 30 mA, it is necessary to increase the connection to the load or reduce the excitation power. When tuning tetrode amplifiers, it must be remembered that the anode current increases with increasing excitation power; The screen grid current is maximum at resonance or weak connection with the load. When adjusting the amplifier for maximum output power, you should not exceed the parameters specified in the specifications for optimal linearity. The required amplifier excitation power decreases in high frequency ranges. This is explained by the influence of the cathode-heater capacitance, which shunts resistor R2, reducing the environmental impact. This must be kept in mind to avoid over-exciting the amplifier on 15 and 10 meters. (Or use an RF choke in the filament circuit. Ed.)

The amplifier parameters with an input power of about 45 W are given in Table 1. (The output power value seems to be somewhat overestimated. Editor's note.) Before turning off the amplifier after a session, you need to leave it in the standby position for about three minutes - the fan should cool the lamp.

Table 1
Anode voltage 2200 V
Anode quiescent current 170 mA
Maximum anode current 550 mA
Screen grid current maximum 25 mA 0
Power dissipation at the anode without signal 370 W
Power supplied 1200 W
Output power 750W

Part two

The desire to provide reliable and durable performance of a highly linear power amplifier was clearly demonstrated by Mark Mandelkern, KN5S. Schematic diagrams of the amplifier and auxiliary circuits are shown in Fig. 3...8.

Do not be surprised by the abundance of semiconductor devices - their use is justified and deserves attention, especially the use of protection circuits. (However, it cannot be said that all of them are absolutely necessary. Ed.)

When designing the RA, the following goals were pursued:
- power supply of the lamp heater from a stabilized DC source; use of automatic heating and cooling timers;
- measurement of all parameters, including anode current and voltage, without inconvenient switching;
- the presence of stabilized sources of bias and screen voltage, allowing voltage adjustment within a wide range;
- ensuring operability under significant fluctuations in network voltage (this is especially true when working in the field using an electric current generator).

The power source for the heater of powerful generator lamps is rarely given due attention, but it largely determines the longevity of the lamp and the stability of the output power. Warming up of the heater should occur gradually, avoiding current surges through the cold filament. In transmission mode, when intense electron emission occurs, it is very important to ensure a constant filament voltage and, accordingly, a constant cathode temperature. These are the main reasons for using a stabilized power source with a current limiter for incandescent lamps, which eliminates the current surge at the moment of switching on.

The power supply diagram is shown in Fig. 4. The output voltages allow the following adjustment ranges: from 5.5 to 6 V (filament), from 200 to 350 V (screen grid) and from -25 to -125 V (control grid).

The filament voltage stabilizer uses the popular LN723 microcircuit in a typical connection. The significant filament current of the 4CX1000 tetrode (about 9 A) and the connection of the cathode and heater inside the lamp required separate large-section conductors for the high-current circuit (A- and A+); Through the S- and S+ circuit, the output voltage is supplied to the stabilizer comparison circuit. It is best to solder the FU1 10 A fuse rather than use a fuse holder.

The heater control circuit is shown in Fig. 5. The circuit eliminates the use of the amplifier during warm-up and protects the heater from increased voltage if the stabilizer malfunctions. Protection is provided by turning off the heater using relay K2 (Fig. 4). In addition, the air flow sensor through the lamp SA2 (Fig. 4) monitors the performance of the fan. If there is no air flow, this will also cause relay K2 and the filament voltage regulator to turn off.

The warm-up timer (DA3 in Fig. 5) is set to five minutes. According to the specifications, three minutes is enough, but longer heating will extend the life of the lamp. The timer starts only after voltage appears on the heater. This is determined by the comparator DA2.2 connected to point S+. So, for example, if a fuse is blown, the timer will not start until you replace the fuse. When the voltage is exceeded (for example, when the control transistor VT1 breaks down), the trigger on DA2.3 is activated and the transistor VT2 closes, disconnecting the voltage from the winding of relay K2 (point HR in Fig. 5). Capacitor SZ ensures the initial setting of the trigger and, accordingly, the opening of transistor VT2 when the supply voltage is applied.

Along with the warm-up timer, the amplifier needs a timer for the tube to cool down before turning off (DA4). When the amplifier is turned off, the +12 V circuit discharges faster than the +24 V circuit (which has a minimum load in receive mode). A voltage of +24 V appears at the DA2.1 output and the cooling timer starts. After startup, there is a low voltage level at pin 7 of DA4, which triggers relay K1 (Fig. 4), through the contacts of which the operation of the +12/-12 V and +24 V stabilizers is ensured. After approximately three minutes, a high level appears at pin 7, relay K1 returns to its original state, and the amplifier is finally de-energized. The +24 RLY circuit eliminates the operation of the cooling timer if for some reason the amplifier was turned off and immediately turned on. For example, the passage of radio waves ends and the range seems dead - you turn off the amplifier. Suddenly an interesting correspondent appears - the power switch is again in the ON position! When entering transmit mode, the +24RLY voltage forces DA2.1 to a low state and resets the cooling timer.

As in the case of filament voltage, the screen grid voltage stabilizer rarely receives attention when designing a PA. But in vain... Powerful tetrodes, due to the phenomenon of secondary emission, have a negative screen grid current, so the power source of this circuit must not only supply current to the load, but also consume it when the direction changes. Series stabilizer circuits do not provide this, and when a negative screen grid current appears, the series stabilizer transistor may fail. Having lost several high-voltage transistors when setting up the amplifier, radio amateurs come to the decision to install a powerful resistor with a resistance of 5...15 kOhm between the screen grid and the common wire, resigning themselves to useless power dissipation. The use of a parallel voltage stabilizer, which can not only supply, but also receive current, allows for trouble-free operation, but it is advisable to use overcurrent protection.

The screen grid voltage stabilizer is assembled using transistors VT3, VT4 (Fig. 4). Instead of VT3 type 2N2222A, you can use a high-voltage one, excluding the parametric stabilizer R6, VD5, but in this case the stabilization coefficient may deteriorate, because high-voltage transistors have low gain. The output voltage is determined by the sum of the stabilization voltage VD11 and the voltage at the base-emitter junctions of transistors VT3, VT4 (15+0.6+0.6=16.2 V), multiplied by the coefficient determined by the voltage divider R11,R12,R13 (12. ..20) at the output of the stabilizer.

The shunt transistor is mounted directly on an aluminum plate measuring 70x100x5 mm, which, in turn, is mounted on the side wall using ceramic insulators. Resistor R7 limits the peak current through shunt transistor VT4 to about 100 mA.

The RECEPTION-TRANSMIT circuit (Fig. 6) checks six signals: the presence of air flow through the lamp (+12N), the state of the OPERATE-STANDBY switch, the completion of filament heating, the presence of anode voltage, the presence of bias voltage and the state of the overload protection circuit. The reception-transmission switching circuit provides a delay in the operation of the short-circuit relay of 50 ms (Fig. 4) when switching to transmission and a delay in turning off the coaxial relay of 15 ms when switching to reception. If vacuum relays are used, the relay timing can be easily changed for full QSK.

The op-amps of the receive-transmit switching circuit in Fig. 6 use very simple R-C networks to obtain the switching delay. In transmit mode, there is a voltage of about +11 V at the output of DA1.4, which provides a quick charge of capacitor C4 through the diode VD8 of the Kant antenna switching coaxial relay circuit. Capacitor C5 of the screen grid power relay circuit is charged through resistor R26, so the screen relay operates later. When switching to receive mode, a voltage of about -11 V appears at the DA1.4 output, and the reverse process occurs. The KEY input allows you to reduce power dissipation at the anode during transmission pauses and avoid changing the shape of the CW signal sent when working with PA, but for this it is necessary that the transceiver has an appropriate output. The overload blocking circuit (Fig. 7) is triggered when the control or screen grid or anode current exceeds 1 mA, -30 mA and 1150 mA, respectively. The screen grid overload protection circuit operates only at negative currents. The positive current limiter of the screen grid is resistor R27 in the voltage stabilizer circuit. Triggering of the overload protection circuit (Fig. 8) causes the TRANSMISSION circuit to be turned off via the OL circuit (Fig. 6), the additional resistor R2 in the control grid bias circuit is turned on using relay contacts K1, the generator on DA2.4 is turned on and the red LED flashes VD9 OVERLOAD on the front panel.

Only the DA2 microcircuit is powered from a unipolar +24 V source (Fig. 5). All other op amps use +12/-12 V supply voltage.

Figure 7 shows the measurement diagram. Five pointer instruments allow you to measure 10(!) parameters using additional buttons: direct/reflected power in the antenna, control grid current/voltage, anode current/voltage, screen grid current/voltage, filament voltage/current. To read the parameter values ​​indicated through a fraction, you must press the corresponding button. Basic parameters are read immediately; Secondary parameters are of great importance only for the initial setup and for adjustments after replacing the lamp. The simplest non-inverting amplifier used here is to measure the anode voltage (DA2.1). Let us assume that the measurement limit should be 5000 V; The divider R7, R8 (Fig. 3) has a division coefficient of 10,000, i.e. 5000 V at point HV2 is 0.5 V. Resistor R9 does not affect the operation of the circuit since the op-amp has a high input impedance. With a supply voltage of +12/-12 V, the maximum output voltage of the amplifier is about +11/-11 V. Let us assume that +10 V of the output voltage of the operational amplifier corresponds to the full deflection of the meter needle when using a 10 kOhm resistor R22 and a 1 mA device. The required gain (10/0.5) is 20. Having chosen R15 = 10k0m, we find that the feedback resistor should have a resistance of 190 kOhm. The specified resistor is composed of a trimming resistor R20 with a resistance of approximately half the nominal value and a constant resistor R19, selected from a number of standard values.

The anode current measurement circuit is similar. A voltage proportional to the anode current is removed from the negative feedback resistor R2 in the cathode circuit (Fig. 3). Capacitor C2 provides damping of the readings of the measuring device ONCE during SSB operation.

Screen voltage is measured in a similar way. The values ​​of the resistors that determine the gain of the forward and reverse power measurement circuits depend on the design of the directional coupler.

The screen grid current measurement circuit is implemented somewhat differently. It was indicated above that the screen grid current can have both negative and positive values, i.e. a measuring device with a zero in the middle is required. The circuit is implemented on a DA2.3 operational amplifier and has a measurement range of -50...0...50 mA, using a conventional device with a zero on the left for indication.

At 50 mA positive screen grid current, the voltage drop across resistor R23 (Fig. 4) is -5V at point -E2. Thus, a gain of -1 is required from the op amp to produce the required +5V output voltage to deflect the needle by half scale. When R23=10 kOhm, the feedback resistor should have a nominal value of 10 kOhm; tuning resistors R32 and constant resistors R30 are used. To shift the instrument needle to the middle of the scale at a supply voltage of -12 V, a gain of +5/-12=-0.417 is required. The exact value of the gain and, accordingly, the zero of the scale is set by trimming resistor R25.

Operational amplifiers DA2.2, DA2.4 have an extended filament voltage measurement scale. The differential amplifier DA2.2 converts the filament voltage to unipolar, because point S is not directly connected to the common wire. The DA2.4 summing amplifier implements an extended measurement scale - from 5.0 to 6.0 V. In fact, it is a voltmeter with a measurement limit of 1 V, biased to the initial value of 5 V.

In rectifier circuits, the diodes used must be designed for the appropriate current, the rest - any pulsed silicon diodes. With the exception of high-voltage transistors, any low-power corresponding structure can be used. Operational amplifiers - LM324 or similar. Measuring instruments - PA1...PA5 with a total deviation current of 1 mA.

The above schemes certainly complicate RA. But for reliable everyday work on air and in competitions, it’s worth spending extra effort on creating a truly high-quality device. If there are more clean and loud signals on the bands, then all radio amateurs will benefit. For QRO without QRM! I express my gratitude to I. Goncharenko (EU1TT), whose advice and comments were of great help when working on the article.

Literature

1. Bunimovich S., Yailenko L. Amateur single-sideband radio communication technology. - Moscow, DOSAAF, 1970.
2. Radio, 1986, N4, P.20.
3. Drozdov V. Amateur KB transceivers. - Moscow, Radio and Communications, 1988.
4. QST ON CD-ROM, 1996, N5.
5. http: //www.svetlana.com/.
6. QEX ON CD-ROM, 1996, N5.
7. QEX ON CD-ROM, 1996, N11.
8. Radio amateur. KB and UKV, 1998, N2, P.24.
9. Radio Amateur, 1992, N6, P.38.
10. ALPHA/POWER ETO 91B User's Manual.

G.LIVER (EW1EA) "HF and VHF" No. 9 1998

Most audio lovers are quite categorical and are not ready to compromise when choosing equipment, rightly believing that the perceived sound must be clear, strong and impressive. How to achieve this?

Search data for your request:

Left-handed amplifiers and transceivers

Schemes, reference books, datasheets:

Price lists, prices:

Discussions, articles, manuals:

Wait for the search to complete in all databases.
Upon completion, a link will appear to access the found materials.

Perhaps the main role in resolving this issue will be played by the choice of amplifier.
Function
The amplifier is responsible for the quality and power of sound reproduction. At the same time, when purchasing, you should pay attention to the following designations, which mark the introduction of high technologies in the production of audio equipment:

• Hi-fi. Provides maximum purity and accuracy of sound, freeing it from extraneous noise and distortion.
• Hi-end. The choice of a perfectionist who is willing to pay a lot for the pleasure of discerning the smallest nuances of his favorite musical compositions. Hand-assembled equipment is often included in this category.

Specifications you should pay attention to:

• Input and output power. The rated output power is of decisive importance, because edge values ​​are often unreliable.
• Frequency range. Varies from 20 to 20000 Hz.
• Nonlinear distortion factor. Everything is simple here - the less the better. The ideal value, according to experts, is 0.1%.
• Signal to noise ratio. Modern technology assumes a value of this indicator over 100 dB, which minimizes extraneous noise when listening.
• Dumping factor. Reflects the output impedance of the amplifier in its relation to the nominal load impedance. In other words, a sufficient damping factor (more than 100) reduces the occurrence of unnecessary vibrations of equipment, etc.

It should be remembered: the manufacture of high-quality amplifiers is a labor-intensive and high-tech process; accordingly, too low a price with decent characteristics should alert you.

Classification

To understand the variety of market offers, it is necessary to distinguish the product according to various criteria. Amplifiers can be classified:

• By power. Preliminary is a kind of intermediate link between the sound source and the final power amplifier. The power amplifier, in turn, is responsible for the strength and volume of the output signal. Together they form a complete amplifier.

Important: the primary conversion and signal processing takes place in the preamplifiers.

• Based on the element base, there are tube, transistor and integrated minds. The latter arose with the goal of combining the advantages and minimizing the disadvantages of the first two, for example, the sound quality of tube amplifiers and the compactness of transistor amplifiers.
• Based on their operating mode, amplifiers are divided into classes. The main classes are A, B, AB. If Class A amplifiers use a lot of power, but produce high-quality sound, Class B amplifiers are exactly the opposite, Class AB seems to be the optimal choice, representing a compromise between signal quality and fairly high efficiency. There are also classes C, D, H and G, which arose with the use of digital technologies. There are also single-cycle and push-pull operating modes of the output stage.
• Depending on the number of channels, amplifiers can be single-, double- and multi-channel. The latter are actively used in home theaters to create volumetric and realistic sound. Most often there are two-channel ones for right and left audio systems, respectively.

Attention: studying the technical components of the purchase is, of course, necessary, but often the decisive factor is simply listening to the equipment according to the principle of whether it sounds or not.

Application

The choice of amplifier is largely justified by the purposes for which it is purchased. We list the main areas of use of audio amplifiers:

1. As part of a home audio system. Obviously, the best choice is a tube two-channel single-cycle in class A, and the optimal choice can be a three-channel class AB, where one channel is designated for a subwoofer, with a Hi-fi function.
2. For car audio system. The most popular are four-channel AB or D class amplifiers, depending on the financial capabilities of the buyer. Cars also require a crossover function for smooth frequency control, allowing frequencies in the high or low range to be cut as needed.
3. In concert equipment. The quality and capabilities of professional equipment are reasonably subject to higher demands due to the large propagation space of sound signals, as well as the high need for intensity and duration of use. Thus, it is recommended to purchase an amplifier of at least class D, capable of operating almost at the limit of its power (70-80% of the declared one), preferably in a housing made of high-tech materials that protects from negative weather conditions and mechanical influences.
4. In studio equipment. All of the above is also true for studio equipment. We can add about the largest frequency reproduction range - from 10 Hz to 100 kHz in comparison with that from 20 Hz to 20 kHz in a household amplifier. Also noteworthy is the ability to separately adjust the volume on different channels.

Thus, in order to enjoy clear and high-quality sound for a long time, it is advisable to study in advance all the variety of offers and select the audio equipment option that best suits your needs.