Linear amplifier on gk 71. Power supply: circuit diagram

The power amplifier (PA) is made on the "old" reliable GK71 lamp, with a graphite anode that does not require airflow. The schematic diagram is shown in fig. one.

The scheme is classical with a common grid (OS). Anode voltage - 3 kV, screen grid voltage - +50 V, filament voltage - 22 V, in "Sleep mode" - 11 V. Quiescent current - 100 mA. The buildup power Rvx is 50-80 watts.

Power delivered to a load equivalent of 50 ohms Pout = 500-700 W.

The features of this UM scheme are:

• the introduction of a protection circuit against overcurrent and short circuit (short circuit) and the maintenance of "Sleep mode" in the MIND;
• the use of a cathode resonant circuit for better matching with imported transceivers;
• the original P-loop circuit, which allows you to get the same output power on all ranges.

Rice. 1. Schematic diagram of the GK71 power amplifier with a common grid.

The PA is powered by one powerful transformer made on a torus. A high anode voltage of 2.5-3.0 kV is obtained by doubling the voltage taken from the step-up winding of the transformer.

When the PA is turned on, the mains voltage of 220 V, passing through the mains filter Lf, C42, C43, SA4 circuit breaker, is fed to the primary winding of the transformer through the HL1 halogen lamp. This provides a “soft” start and extends the life of the VL1 GK71 lamp and other PA elements.

After the capacitors are charged, part of the high voltage taken from the divider R13-R18 and the potentiometer R12 is fed to the automation circuit, made on a transistor? ТЗ. If there is no short circuit in the PA circuit, the voltage is normal, then? TZ opens, relay Kb is activated, closing the halogen lamp HL1 with its contacts K6.1.

A feature of this automation scheme is the "small hysteresis" of actuation / release of Kb. This provides reliable protection of the PA from overcurrent of the anode or short circuit in the secondary circuits, breakdown and short circuit in the transformer windings, at which?

In standby mode, an incomplete 11V glow voltage is supplied to the GK71 lamp. This ensures low heating of the lamp, the PA as a whole and the “Sleep Mode” of the PA. When switching to "TX", the full filament voltage of 22 V is applied to the GK71, and already after 0.2-0.25 s, the PA is ready to operate at full power, which is the undoubted advantage of direct filament lamps GK71, GU13, GU81.

To fully match the PA with imported transceivers, a “Cathode Circuit” is used, which is tuned to resonance on each range by connecting capacitors to L1 using the K9-K13 relay on the 10-24 MHz bands.

Initially, the L1 circuit is tuned to the 28 MHz range by the capacitor C21. On the low frequency ranges of 3.5 and 7 MHz, for more complete matching (due to the narrow band of the L1C cathode circuit), the signal is fed through the contacts of the K7 relay to the cathode three-winding choke - Dr1. At the same time, to exclude the influence of L1, it is short-circuited by the RF capacitor C14 through contacts K8.1.

The SWR at the PA input does not exceed 1.5 on all bands and is in good agreement with any imported transceiver, even without a tuner.

The output P-circuit of the PA is switched by a 3-way switch SA1. SA1.3 - switches the taps of the coils and connects an additional capacitor C23 to the KPI C22 connection with the antenna on the 3.5 MHz band.

Switch SA1.2 shorts the 3.5MHz coil. Switch SA1.1 switches range relays. If a 1.8 MHz band is planned, then you need to add another relay and use the 9th position on the SA1 switch.

The L4 coil operates on the 28 MHz range, which is located directly in the GK71 anode circuit. This made it possible to obtain Pout at 28 MHz the same as on the low bands. Dr3 is necessary to protect the output circuits of the PA.

The “RX / TX” control is carried out by the circuit on the transistor VT1, which is powered by a voltage of +24 V. When the RX / TX input of the XS1 connector of pin 3 is closed to the case (current 3-5 mA), the circuit on the transistor? T1 opens, the short circuit relay is activated and through contacts K3.1, +24 V is supplied to relays K1 and K2. The K4 relay is activated, supplying the full glow voltage to the GK71 through contacts K4.1.

If the SA3 "Glow" switch is on, the full glow voltage is constantly applied to the VL1 lamp. This may be necessary when working in TESTax. After charging the capacitor C3 (after 0.15-0.2 s), relay K5 will operate, which provides:

• correct operation of the UM;
• no burning of relay contacts K1, K2.

Relay K5 with contacts K5.1 closes the circuit of the control grid of the VL1 lamp to the housing, opening it. To implement the “Bypass” mode, the SA2 switch breaks the +24 V supply circuit of the circuit on? T1 of the “RX / TX” switch. On the transistor? T2, an adjustable voltage regulator of the screen grid of the lamp VL1 is made.

Potentiometer R4 sets the quiescent current VL1 in the range of 100-120 mA. On the DA1 chip, a +24 V voltage regulator is made to power the relay and the automation circuit. In case of overloads and short circuits at +24 V, DA1 automatically turns off, which also increases the reliability of the PA as a whole.

Power amplifier design

The UM is made in the body of the computer system unit, preferably the old model of the 80s - it is made of thicker steel. Dimensions 175x325x400 mm. The vertical partition and horizontal shelves are made of steel 1.5-2 mm thick.

With intensive work of the PA, it is desirable to use a fan operating at a reduced supply voltage to reduce noise.

Parts and possible replacements

Transformer T1 is made on iron from LATR-8 10 A. The network winding is wound with PEL wire 1.5 mm. Step-up winding PEL 0.65-0.7 mm, voltage 1.1-1.2 kV. Filament winding PEL 1.5 mm 11 + 11 V, other PEL windings 0.5-0.65 mm for voltages of 22 V and 50 V.

Circuit breaker SA4 type VA-47 for 10 A. The cathode choke Dr1 is wound on a ferrite ring K45x27x15 mm 2000NN in two wires 1.2-1.5 mm and contains 12 turns. The communication coil has 7 turns of MGTF0.2 mm wire, evenly distributed between the turns of the main winding.

Coil L1 of the cathode circuit is made of a copper tube with a diameter of 5-6 mm. Inside which a wire is stretched in heat-resistant insulation MGTF, BPVL with a cross section of at least 1 mm2. The outer diameter of the coil is 27-30 mm, the gap between the turns is 0.2-0.3 mm and contains 8 turns, tapped from the middle.

The L2 coil of the 3.5-7 MHz range is made on a frame with a diameter of 40-45 mm and contains 15 + 12 turns of wire 1.5-2.0 mm. The first 15 turns for the 3.5 MHz band are wound turn to turn, and the remaining 12 turns in 2.5 mm increments.

The L3 coil of the 10-21 MHz range is made of a copper tube with a diameter of 5-6 mm and contains 15-17 turns, the outer diameter is 50-55 mm.

The L4 coil of the 28 MHz range is made of copper wire with a diameter of 2.0-2.5 mm and contains 5-6 turns, the outer diameter of the coil is 25 mm.

The anode choke Dr2 is wound on a frame made of PTFE with a diameter of 18-20 mm, a length of 180 mm, a PELSHO wire of 0.35 mm, a turn to turn in sections of 41 + 34 + 32 + 29 + 27 + 20 + 17 + 11 turns and the last 10 turns in discharge in 2 mm increments.

Dr3 - winding station wagon with PELSHO wire 0.2-0.3 mm 2-4 sections of 80-100 turns.

The mains filter Lf is wound on a K45x27x15 mm 2000NN ring in two wires with a diameter of 1 mm, with good insulation of the MGTF type, turn to turn until filled.

Anode KPE C24 from UHF-66. One section, gap 2.5-2.7 mm 15-100 pF, connected to the 2nd turn of the L3 coil. Capacitor C23 - connection with the antenna KPI 2-3 sections from old radios with a gap of 0.3-0.4 mm, 30-1200 pF.

Relay K1 - REN-33, K2 - REN-34. Relays KZ-K6 - small-sized imported plastic cases 15x15x20 mm, switching current 6-8 A, switching voltage 127-220 V. Relays KZ and Kb for an operating voltage of 24 V, and relays K4 and K5 for an operating voltage of 12 V. Relay K7 -K13 - RES-10 low-power silicon diodes are connected in parallel with the relay windings. Diodes are not shown in the diagram.

Transistors VT1 - KT835, KT837. VT2, VT3 - KT829A. DA1 - KR142EN-9 (B, D) or MC7824.

Decide on the use of good old glass lamps in the power amplifier (PA), then you will forget about blowing, warming up, training and so on.

500W output power is better than 100W! The PA is designed to operate on amateur bands 10, 12, 15, 17, 20, 30.40, 80 m and 160 m. Peak output power in the absence of distortion of the amplified signal is 500 watts.

It is made on a VL1 type GK71 lamp, connected according to the classical scheme with a common cathode. The input impedance of the amplifier and the stability of its operation on all ranges are provided by the resistor R1, which allows the imported transceiver (and the amplifier is designed for it) to operate at a constant load of 50 ohms with a minimum SWR.

Rice. 1. View of the front panel of the power amplifier (PA).

With a transceiver output power of 5 watts, the amplifier delivers 500 watts of peak power. The required small input power of the PA allows it to be used with imported and home-made transceivers with a maximum output power of up to 10 W, which have output power control.

The anode circuit of the VL1 lamp is made according to the serial power supply scheme. Which also has a beneficial effect on increasing the coefficient of performance (COP) of the amplifier in the HF bands.

If today many shortwavers have the opportunity to use branded transceivers, then power amplifiers, as a rule, are forced to manufacture their own. This section proposes a complete design of a modern PA for an amateur HF radio station.

The common cathode (CC) circuit has a high input impedance across the first grid. The input signal source is required to provide only a small reactive current through the input capacitance of the lamp, and there is no active component of the grid current, moreover, its appearance is harmful, therefore, a small input power is sufficient for the PA to work with OK. In a real circuit, the power gain of a circuit with OK can reach several tens of decibels.

It should be noted that the PA according to the circuit with OK is sensitive to overload by the input signal. In addition, due to intermodulation distortion, the radiated frequency band of the SSB signal is greatly expanded.

It is important to comply with the passport data of the lamp modes, it is necessary to accurately withstand the filament voltage. An underestimated filament voltage has a much worse effect on the durability of the lamps than an overestimated one.

By operating an expensive imported transceiver at low power, using a tube PA, we unload the transistor output stage of the transceiver, as well as the power supply to the transceiver.

circuit diagram

The power amplifier, the schematic diagram of which is shown in fig. 2 provides the necessary gain on all nine amateur HF bands. It is made on a VL1 lamp connected according to the common cathode circuit.

In the absence of a control signal at the XS1 connector (the control pedal is not pressed) or the amplifier is turned off, the input signal from the antenna connected to the XW2 RF connector passes through the circuit through the normally closed contacts of the K2 and K1 relays to the XW1 “Input” connector and then to the transceiver.

When switching to transmission mode, the XS1 socket receives a control signal from the transceiver. Through the circuit through the SA3 switch, the short circuit relay winding is supplied with a voltage of +24 V to an open-collector transistor switch in the transceiver. When the transistor key of the transceiver is opened, the short circuit, K1, K2 relays are activated.

Rice. 2. Schematic diagram of the power amplifier (PA).

Trimmer capacitor C4 serves as a tuning of the range circuits. In the receive mode, the relay contacts K3.1 are open. Relays K1 and K2 are de-energized.

Contacts K1.2 are open, a voltage of minus 150 V is supplied to the control grid of the lamp, while the lamp is closed.

It is necessary to choose an offset such that it reliably closes the lamp in the receive mode. A poorly sealed lamp can make noise and interfere with reception.

The contacts of relay K1 K1.2 switch the bias circuit, and a stabilized voltage of minus 80 V is supplied to the control grid in the transmission mode. Relay K2 with its contacts K2.1 connects the antenna to the PA output.

The load is a P-loop, which ensures the matching of the amplifier with antennas having different input impedance. The usual P-circuit C13, L8 and L9, C17 is included in the anode circuit of the lamp.

To prevent self-excitation of the amplifier, a low-resistance resistor R2 is included in the control grid VL1. The anode circuit of the VL1 lamp also includes an element of protection against self-excitation on VHF - a choke Dr3 with a small inductance shunted by a resistor R4 that cuts off its action at operating frequencies. Self-excitation is possible, despite the mythical "low frequency" of GK71.

Inductor Dr2 is connected to the P-loop at the point with the least resistance and RF voltage. Therefore, it does not affect the operation of the amplifier at high frequency. Structurally, it can be placed close to the walls of the amplifier housing, which simplifies the layout.

At high frequency, the inductor is connected in parallel with the load, its shunt action is low and it can have a lower inductance. The required inductance, even with a margin for connecting a high-resistance antenna, is 20-30 μH. Accordingly, the own capacitance and dimensions of the inductor are reduced.

At the output of the P-loop, an indicator of the output signal level (HF voltmeter), elements C18 * is connected. VD5, R6, R7, C19, C20 and PA1, facilitating the setting of the P-loop and correct matching with the antenna. The required sensitivity of the indicator is set depending on the actual input impedance of the antenna by adjusting the resistor R6.

The UM has a bypass mode. SA3 is used to enable it. The lamp operates with maximum linearity in the absence of grid current.

To control the control grid current, it is desirable to turn on a small pointer microammeter. It is useful in measurements and tests. During operation, it can be safely replaced with a low-power VD3 LED, in parallel to which a simple VD4 diode must be connected, through which a bias voltage will be applied to the grid.

The lamp filament is powered by 21-22 V AC. This provides the necessary emission current for linear operation of the amplifier while maintaining a long lamp life.

Design

The PA is assembled on the basis of the legendary transmitter unit from the RSB-5 radio station. This is an aluminum case with a 115 mm chassis basement. Ideal for this design.

The socket of the GK71 lamp is fixed at a height of 55 mm. The housing measures 200x260x260 mm (WxHxD) without protruding elements.

The upper compartment contains the details of the output P-circuit C12, 04, C15, C16, C17, Dr2, L8, L9 - a turntable, relay K2.

The front panel has:

• knob and turntable scale;
• pointer meter RA1;
• variable resistor R6;
• antenna connectors XW2 and XI;
• capacitor handles C4.03, 07;
• switches SA1, SA2;
• switch SA3.

Variable capacitors are equipped with scales, which is very convenient for tuning.

In the lower compartment, C4, 03, coils LI, L1 "- L7, L7 ’, a switch of ranges SA1, relays K1 and short circuit are mounted. Connectors XW1, XS1, XP1, X2 are installed on the rear wall of the lower compartment.

The upper U-shaped cover covering the UM unit has oblong holes on the sides and a raised top cover by 10 mm. There are holes in the cover covering the bottom of the unit to improve the cooling of the amplifier. All this is done to reduce the ingress of dust into the PA.

Parts and possible replacements

At the input of the amplifier, bandpass filters with inductive coupling are installed, providing:

• firstly, galvanic isolation from the transceiver;
• secondly, good range filtering.

The input grid circuits are switched by the SA1 switch. Data input inductors are given in table. one.

Table 1. Input inductor data.

Grid choke Dr1 is wound on a sectioned porcelain frame. Outer diameter - 20 mm, total length - 39 mm. It has 4 sections with a width of 4 mm, the diameter in the section is 11 mm with partitions 2 mm thick.

Wire brand PELSHO 0.1, winding up to filling.

A P-loop is used at the output of the power amplifier. Coil output P-loop L8 - frameless wound on a mandrel with a diameter of 40 mm and contains 5 turns of a silver-plated copper tube with a diameter of 5 mm, winding length - 30 mm. The high quality factor of this coil ensures full power output on the 10m band.

As an inductor L9, a “turntable” and a counter of turns from the RSB-5 radio station or the like, for example, from the Mikron radio station, were used.

P-loop inductors are wound in one direction. During the tuning process, a “turntable” from the R-111 radio station, with an inductance of 1.3 μH, was used as L8. These coils have one drawback - the silver-plated surface oxidizes over time, and contact may be broken, for which it is necessary to clean it.

For this purpose, it is best to use ammonia. Capacitor 03 of the P-loop setting must have a gap between the plates of at least 1.2 mm. A capacitor from the RSB-5 (R-805) radio station is well suited; the gap between the plates is 2 mm.

Capacitor C17 regulates communication with the antenna, the gap is at least 0.5 mm. Capacitor C17 is used from old-style radios, this is a three-section version with a gap of 0.3 mm if the antenna has an input impedance of 50-100 ohms.

If you plan to use antennas with a higher input impedance (for example, Long Wire, VS1AA or "American"), the gap between the C17 plates must be at least 1 mm to avoid unwanted electrical breakdowns of the air gap.

The Dr2 inductor is wound on a ceramic frame with a diameter of 13 mm and a length of 190 mm. Its winding is made with PELSHO 0.25 wire, the number of turns is 160. Up to half of the frame - winding turn to turn, then in sections with 5 mm intervals, and from the hot end part of the turns of the inductor has a progressive winding.

Inductor Dr3 contains four turns of wire, evenly distributed along the length of the body of the resistor R4 type MLT-2.

Connectors: XW1, XW2 - RF connectors SR-50-165f; XS1 - SG-5; X1 - clip-on HF insulator, X2 - clip-on ground. XP1 connector type RP 14-30LO or RP-30.

SA1 - biscuit ceramic switch type PGK 11P 1N two boards. SA2 high-frequency ceramic switch from PCB-5.

Fixed resistors types MT-2, MLT, S1-4, S2-23, R6 - variable resistor type SPO, CH2-2-1. Trimmer resistor R7 SPZ-19, SPZ-38.

Capacitors of type KD, KM, KT, K10-7V, KSO. Trimmer capacitor C4 type KPV, KPVM. Capacitor C14 type K15U-1 150 pF 7 kvar 6 kV.

Capacitor 08 - constructive, is a piece of coaxial cable located near the inductor L9.

SA3 toggle switch type PV2-1, TP1-2, MT1, PT8 or P2K.

The operating voltage of all relays is 24-27 V. The contacts of the high-frequency relays K1 and K2 must withstand a passing power of 100 and 500 W, respectively. Relay K1 - RPV 2/7 with an operating voltage of 27 ± 3 V, winding resistance 1100 Ohm, actuation current 13 mA, release current 2 mA.

Relay winding polarity:

• output A - minus;
• conclusion B is a plus.

Passport RS4.521.952 or RS4.521.955, RS4.521.956, RS4.521.957, RS4.521.958.

You can apply RES-59, passport HP4.500.025. Well suited RES-48 passport RS4.520213. Relay K2 HF type "Hook" or similar for an operating voltage of 24-27 V.

If it is not planned to use antennas of the type Long Wire, VS1AA and the like, then a relay of the TKE54PD1 type is well suited as a K2 relay.

Short-circuit relay type RES15 passport RS4.591.001, RS4.591.007, KhP4.591.014 can be replaced by RES-49, passport RS4.569.421-00, RS4.569.421-04, RS4.569.421-07. All relays are connected by twisted pair.

Measuring device PA1 with a total deviation current of 1 mA type M4231.

Diodes VD1, VD2, VD4, VD6 - KD522 or other silicon, VD3 - AL310, VD5-D2E, D18.

Setting

When setting up a tube PA, all precautions must be observed, since it contains high voltage that is life-threatening. Never turn on the amplifier without the top cover installed.

If used for a long time, the top cover of the amplifier will become very hot, which may cause burns. Do not touch these parts of the PA during operation.

Before removing the top cover, make sure the PSU has been turned off for at least 5 minutes. During this time, the electrolytic capacitors will be completely discharged.

First of all, it is necessary to calibrate measuring instruments by comparing their readings with exemplary ones. It is impossible to select shunts at operating voltages.

Focus on checking the correctness and quality of installation. A PA made without errors usually does not require much adjustment and immediately starts working.

A transceiver is connected to the input of the amplifier. For most imported transceivers, the output power is smoothly regulated. When you first turn on the PA with the transceiver, the power supplied to the PA input must be reduced to a minimum.

The YAESU FT-950 transceiver has a minimum output power of 5W. That's where we started with.

Looking ahead, let's say that during operation, 5 W is quite enough to build up the PA on one or two GK71 lamps. The input non-inductive resistor R1 can be excluded from the circuit. In this case, the SWR with the tuner built into the transceiver turned off on all ranges is 1-1.2, with careful selection of the turns of the communication coil, and with the tuner turned on, the SWR is 1.

With one lamp, the anode current reaches 350 mA. The maximum allowable buildup should not allow the appearance of the control grid current. If you want more power, you should not increase the buildup and prevent the grid current.

In this case, it is better to increase the screen voltage, set the lamp to the same quiescent current, so that the maximum buildup is achieved without the control grid current.

Connect to amplifier output:

• or a load equivalent of type 39-4 per 1 kW, having a voltage output of HF 1:100 on the connector, and a V7-15 tube voltmeter;
• or an incandescent lamp with a power of 500 W for a voltage of 220 or 127 V (used in railway transport).

SA3 - in the "On" position. We turn on the PSU, measure the quiescent current of the lamp, which should be about 30-40 mA.

We adjust the input range circuits to resonance with capacitor C4. The variable capacitor must not be in the extreme position. If necessary, change the number of turns of coils L1-L7.

The exact selection of the turns of the communication coils L1 "-L7 'is carried out according to the minimum of the KVS-meter built into the transceiver.

In the ranges of 18 and 21 MHz, 24 and 28 MHz, the same circuits L6, L6 'and L7, L7 "work.

The switch SA2 connects the variable anode capacitor C13 on the bands 160-30 m, and on the band 160 m - additional capacitor C14. Capacitor C13 is off on 20-10m bands. In this case, the adjustment is made by the inductor L9 and the coupling capacitor C17.

Finally, connect the antenna with which the PA will work. Do not turn on the PA without an antenna connected. After switching on without an antenna, life-threatening high voltage can be generated at the antenna connector.

There are three controls. On low-frequency ranges, the anode capacitor C13 is set to a large capacitance and inductance. By varying the inductance, we set the output circuit to resonance, and with the capacitor C17 we establish the necessary connection with the load.

To avoid false tuning, the rule to follow is that capacitances C13 and C17 should always be set closer to the maximum value, which will also correspond to maximum harmonic suppression.

By manipulating capacitors C13, C17, inductance L9, the output indicator PA1 is maximum reading on each range. At the same time, keep an eye on the decline in the anode current.

For reliable operation of the PA, good grounding is necessary. To remove static electricity induced in the antenna, it is useful to turn on the throttle from the SW2 connector to the housing.

The data of the anode capacitor is as follows:

• range 160 m - 270 pF;
• range 80 m - 120 pF;
• range 40 m - 70 pF;
• range 30 m - 39 pF;
• on other ranges - the anode capacitor is disabled.

During operation, for a quick transition from range to range, it is necessary to compile a table of the positions of the capacitor rotors corresponding to them and the readings of the turntable counter.

the method of calculating the P-loop is familiar to readers of this book, It is described in the reference literature. There are ready tables for different Roe. There are many virtual calculators on the Internet for such calculations.

Calculations say that at 28 MHz you need a circuit with an inductance of 0.5 μH and a capacitance of the "hot end" of the P-loop - 40 pF. And we have 2 GK71 Cout \u003d 17x2 plus C installation \u003d 45-50 pF. Here we can conclude that 2xGK71 will not work at 28 MHz.

The way out of the situation is to use the serial power supply of the P-circuit, and use the Dr2 inductor with a lower inductance, which is now not included in the mounting capacity. We generally exclude the anode variable capacitor from the circuit.

Lamp training

I had to experiment a lot with GK71, they do not need training. But it is advisable to train random and long-life lamps in this sequence.

Rinse dirty lamps in water with washing powder, rinse thoroughly so that the water rinses the inside of the base and dry. Spare lamps, which also did not work for a long time, are useful to train. In the future, they will be ready for work immediately and guaranteed.

Hold the lamp under incandescence for several hours, then apply bias voltage. Next, apply a reduced anode and screen voltage, reduce the grid bias until a small anode current appears, and again withstand several hours.

We reduce the bias voltage until the anode current is obtained, so that the anodes turn slightly pink, let them bake for a while.

From working lamps, from time to time it is necessary to remove dust from the top of the cylinder with a dry, clean rag (with the PA turned off and the capacitors discharged).

Feeding the filament of a powerful generator lamp

Properly chosen filament voltage of a powerful generator lamp will allow the lamp to serve several times longer, increase the reliability of its operation and facilitate its temperature regime. It is done like this.

We turn on the LATR in the primary winding of the filament transformer, set the nameplate filament voltage. We tune the PA to maximum power with a single-frequency signal. At full power, slowly reduce the voltage supplied from the LATR until the output power begins to decline.

We add the filament voltage by 10% (this is the emission margin). We measure the voltage on the primary winding of the filament transformer. In series, we select a quenching resistor in the primary winding of the transformer to obtain the measured voltage, at the rated mains voltage.

Mounting UM

The input range circuits are located in the basement of the chassis. Details of the anode load of the lamp - above the chassis. The conductors of the RF circuits are as short as possible and preferably straight from a single-core silver-plated copper wire.

The layout of the PA is visible in the photograph (Fig. 3). Photo of the internal layout of the amplifier from the rear panel.

A variant with two GK71 lamps is shown in fig. 4.

Rice. 3. View of the power amplifier (PA) on the right.

Rice. 4. View of the power amplifier (PA) from behind.

Power supply: features

Each source must deliver the required voltage and current at the maximum load of the amplifier operation. It is necessary to check them when the mains supply voltage changes in the line.

The mains voltage changes during the day. It usually falls in the evening and peaks in the middle of the night. Depends on the season, the remoteness of the home from the transformer substation and the state of the electrical network.

In the power supply unit (PSU) to the PA, the primary (network) winding has taps and with large fluctuations in the mains voltage, especially in rural areas, it is possible to adjust the voltage.

It should be taken very seriously to stabilize the voltage on the screen grid of the lamp.

For this you can use:

• a separate winding on the anode transformer or a separate small transformer;
• powerful semiconductor zener diodes of the type D817, D816 on radiators.

For the anode power supply of the lamp, an unstabilized voltage is usually used. But the larger the capacitance of the filter capacitors, the less distortion will be during SSB operation and the clearer the signal will be during CW and DIGI operation.

It must be remembered that, no matter how good and linear the lamps used are, the foundation for the high-quality operation of the PA is its power supply. The authors advise not to save on the power of the anode transformer and on the capacitances of the anode voltage filter.

The design of the PA separately from the PSU makes it easy to upgrade any node of the unit without affecting the other. The PSU is located under the table, the compact UM is in a convenient place. The PSU is made according to a simplified scheme without automatic switching on and off.

It is possible to step change the anode voltage, which is performed by switching the network winding (switch when the PSU is disconnected from the network!). The anode rectifier is built on a bridge circuit with a filter capacitor consisting of series-connected electrolytic capacitors.

Power supply: circuit diagram

The power supply circuit is shown in fig. 5. The power supply of the amplifier consists of two transformers T1, T2 and the corresponding rectifiers. Fuses FU1 and FU2 are included in the network windings.

Rice. 5. Schematic diagram of the power supply unit (PSU) for the power amplifier on GK71 lamps.

From transformer T1 we get:

• filament voltage ~ 20 V at a current of 3 A (6 A) with a midpoint;
• voltage +24 V used to power the relay windings;
• voltage +30 V to power the third grid of the lamp.

There is a separate winding ~ 6.3 V. A transformer is used from a lamp black-and-white TV TS180 with rewound secondary windings. The network winding can be switched on for 220 V, 237 V and 254 V.

Transformer T2 with a power of 1000 W, in which the secondary windings are wound. Outputs from the mains winding are provided for switching to another voltage. These outputs can be used in field (rural) conditions with under or over voltage of the mains.

From the secondary windings we get:

• blocking voltage -150 V;
• stabilized bias voltage bias voltage -80 V;
• stabilized screen voltage +450 V.

If necessary, there is a voltage of +500 V and +1800 V.

The diode bridge VD5-VD12 is used to obtain a voltage of +500 V. The filter consists of an inductor Dr1 and capacitors C2, C3. Zener diodes VD13-VD15 and resistor R4 are used to obtain a stabilized voltage of +450 V.

The diode bridge VD16-VD19 is loaded on the electrolytic capacitor C4 and then the zener diodes VD20-VD22 are turned on, we get -150 V and during transmission - a stabilized voltage of -80 V.

Diode bridge VD23-VD26 and smoothing capacitors C6-C11 are used to obtain high voltage. Each PSU electrolytic capacitor is shunted with a 68-100 kΩ MLT-2 resistor to equalize the voltage and discharge them after the PSU is turned off.

The device RA1 serves to control the anode current. The PA1 device has a current measurement limit of 1 A.

Through the XP1 connector, the necessary voltages are supplied from the PSU to the PA via a multi-core cable. For filament circuits, the cable cores are soldered in parallel. To increase the insulation, a PVC cambric of the appropriate diameter is additionally put on top of the main insulation on the high-voltage wire.

A more preferred option, which is used in many amateur radio developments, is to supply anode voltage from an external power supply unit to the SR50 high-frequency connector via a piece of RK-50 or RK-75 coaxial cable with a diameter of 7-12 mm. At the same time, in order to increase safety, the screen braid of the cable is connected to the PA and PSU cases.

When the PSU is turned on with the SA1 toggle switch, the filament voltage and the voltage to power the relay are supplied. Toggle switch SA2 turns on the blocking voltage, the screen grid and the anode voltage. When switching off, the voltage is relieved in the reverse order.

Control lights HL1, HL2 are used to control the inclusion of transformers T1, T2, respectively.

The PSU is assembled in a separate case. It has dimensions of 390x230x230 mm, chassis basement 50 mm, weight about 20 kg. On the front panel of the PSU case there are network switches SA1, SA2, fuse holders FU1, FU2, bulbs HL1, HL2, device PA1, and on the rear wall there is an XP1 connector and an X1 clamp terminal. The inscriptions on the front panel are made using a transfer font.

Power supply: parts and analogues

Connectors: X1 - terminal-clamp; XP1 - 30-pin connector type RP14-30L0 or RPZ-ZO. Trimmer resistors R1-R2 of the PEVR type with a power of 5-15 W, R13 - a shunt to the specific RA1 device used.

Electrolytic capacitors C1 - 150 uF x 70 V, C2, C3 - K50-7 with a capacity of 50 + 250 uF x 450/495 V, C4 - 100 uF x 295 V.

The use of modern or imported capacitors for a large capacity and voltage will only benefit, increase reliability.

Capacitors C2, C4, C6-SP are installed through an insulating washer made of foil fiberglass. The foil serves as the negative contact of the electrolytic capacitor. Capacitors C5, C12 type KD, KM, KT.

Switches SA1, SA2 - toggle switches TV 1-2 250 W / 220 V or B4 250 W / 220 V.

Diodes VD1-VD4 KD202V, VD5-VD12 and VD16-VD19 2D202K or assembled from similar diodes or diode assemblies for the appropriate voltage and current.

Remember about equalizing resistors and capacitors with a capacity of 10000-47000 pf - protection against possible breakdown by short-term pulses, they are not shown in the diagram.

VD23-VD26 - type KTs201D, VD13-VD15 - KS650, VD20 - D817D, VD21 - D817V, VD22 - D817B zener diodes or a set of other zener diodes with the appropriate stabilization voltage, mounted on radiators and isolated from the case.

Measuring device PA1 with a total deviation current of 1 mA, type M4200, M2003, M4202. The power transformer T2 is made of an industrial one, having a primary winding of 220/380 V. In addition, without disassembling the transformer windings, an additional output was made from the primary winding between 220 V and 380 V.

Thus, it turned out the possibility of discrete voltage regulation. All transformers must be impregnated with high quality varnish so that air humidity and dew, especially in the field, do not cause breakdown of the windings.

In the BI version for field conditions, the basement of the chassis was made of thick plexiglass. Holes were made in plexiglass, and appropriate threads were cut for attaching electrolytic capacitors.

Operating experience

Several UMs were made according to the described scheme. There were options with one lamp and with two GK71 lamps operating in parallel. They are in use to this day.

To keep the PA in constant readiness and operate at maximum power, set the P-loop to maximum power. If you want to conduct radio communication with neighbor friends, turn down the buildup from the transceiver and communicate at low power.

The power to the maximum in the PA is increased quickly by simply entering the transceiver menu and adding the drive power from the transceiver. The maximum power is used when you need to work quickly with DX, in competition or in poor passing conditions.

In this UM, instead of GK71 lamps, GU13, GU72 and others can be used. This PA is easily consistent with both a low-resistance load of 50 ohms and a high-resistance load when the antennas are powered by a single-wire line.

Each time the "TX" mode is turned on, the voltage from the collector of the transistor VT1 through the resistor R3 opens the transistor VT8 and discharges the capacitor C6. But if it manages to fully charge, the VT10VT11 composite transistor opens and closes the base circuit of the VT4 transistor to a common wire. The transistor closes, relay K3 is de-energized and the glow of the GK-71 lamps is turned off. The fans are also turned off, and the network windings of the transformers T1, T2 are reconnected through the EL1 lamp, and the HL4 "Sleep" indicator LED lights up.

In this mode, the PA consumes no more than 50 W of power and can be in constant readiness for operation for an arbitrarily long time. It is enough to press the pedal, and after 1 second it is ready for active work at full power!

The power supply for all relays and automation units is provided by a rectifier-doubler on diodes VD11, VD12 and capacitors C23, C24.

The SA3 switch selects the filament voltage of the VL1, VL2 lamps 22 V or 17 V, and the full filament voltage is constantly supplied through the SA2 switch, which is sometimes necessary when working in contests.

The node on the transistor VT3 serves to protect against breakdown and burning of the plates of the rotor / stator of the capacitor C1 (for example, in the event of a break in the antenna). If an RF voltage of more than 300 V appears on the capacitor, it will go through the divider on resistors R46, R47 and the VD27 diode to the base of the VT3 transistor, which will open, shunting the base of the VT4 transistor, and the amplifier will switch to Sleep mode. The protection threshold is regulated by a trimming resistor R48.

The amplifier is assembled in a vertical case with dimensions of 240x420x420 mm (Fig. 2). Its frame is welded from a steel angle 15x15 mm, which gives the body the necessary strength. The internal volume of the frame is divided in half by a vertical partition, which, in turn, is divided at a height of 220 mm from the bottom by a horizontal subchassis. All components and parts of the amplifier are located in the resulting four compartments (Fig. 3). This arrangement provides easy access to the installation and good cooling of the elements.

Rice. 2. Amplifier assembly

Rice. 3. Nodes and parts of the amplifier

On the front panel of the amplifier are the controls, indication and control. The axes of the tuning resistors are brought out "under the slot" below the level of the "PWR", "QRP", "TUNE" toggle switches. On the rear panel are installed RF connectors XW1, XW2, ground terminal, connector X1 "PTT", fans.

All RF connectors, ground terminal, blocking capacitors and KPE C1, C31 are interconnected by a copper strip 15x0.5mm, passing along the center line between the front and rear panels.

Coil L1 is wound with a copper tube with a diameter of 5 mm on a mandrel with a diameter of 50 mm. The number of turns is 10, the winding pitch is 8...12 mm. Its inductance is 2.8 uH. The taps at the coil are made from the 3rd, 4th, 6th and 8th turns, counting from the output connected to the capacitor C30. The L2 coil is wound with PEV-2 1.5 wire on a ceramic frame with a diameter of 50 mm. The number of turns is 27, the inductance is 24 μH. The taps are made from the 3rd, 8th, 15th turns, counting from the pin connected to the L1 coil.

Coil L3 - four sections of 80 turns each with "Universal" winding with PELSHO 0.2 wire on a ceramic frame with a diameter of 8 mm. Distance between sections - 2,5 mm. Inductance - 250...350 uH.

The low-pass filter coils L4, L5 are wound with PEV-2 0.7 wire on a mandrel with a diameter of 8 mm. The number of turns is 10, the inductance is 1.1 μH.

The anode choke L10 is similar in design to the choke from Um "Ameritron". It is wound with 0.38 PETV-2 wire on a ceramic frame 24 mm in diameter and 180 mm long. Winding - turn to turn, sectional - 82 + 55 + 42 turns. Distance between sections - 20 mm. After winding, the sections are impregnated with insulating varnish or BF-2 glue.

The mains filter coils L11, L12 are wound halfway from the magnetic core of the TVS-110 transformer. Winding - bifilar wire MGTF1.0 until filling.

The anode transformer T1 is made on a toroidal magnetic circuit from LaTR-1M / 9 A (overall power - 2 kW). The network winding I contains 240 turns of PETV-2 1.4 wire. The no-load current should not exceed 0.3 A. High-voltage winding II (1100 V) - 1250 turns with PETV-2 wire 0.67. Winding III power screen grid (270 V) - 580 turns with wire PEV-2 0.45.

The power of transformer T2 must be at least 200 watts. Winding voltage II - 100 V, winding - with a wire with a diameter of 0.2 ... 0.3 mm, winding voltage III - 21 V, wire - with a diameter of 0.7 mm. Winding IV (power supply for incandescent lamps) - 22 V (outlets from 17 V and 10 V), wire - 1.5 mm in diameter.

The T3 transformer is made on a toroidal magnetic circuit OL 70x40x20 mm (from an industrial current transformer). Its primary winding contains three turns of PEV-2 1.4 wire, distributed evenly around the perimeter. Secondary winding - 75+25+25+25+25+25 turns with wire PEV-2 0.45.

The T4 RF transformer is made on an annular magnetic circuit of the K20x10x5 mm size from ferrite grade 200-400NN. Winding II contains 20 turns of wire PETV-2 0.38. Winding I is a wire passed through the hole of the magnetic circuit and connecting the connector XW2 with the switching contact of the relay K2.1.

The T5 transformer is wound with PEV-2 0.7 wire on a ring magnetic wire of size K30x20x6 mm made of VCh20 grade ferrite. Winding - in three interlaced wires with a step of two twists per centimeter. The number of turns is 10.

Due to the large variation in the parameters of domestic ferrites, the number of turns and the twist pitch are selected during tuning.

All relays in the amplifier are for a rated voltage of 24 V. Relays K1, K3 - REN33, K2 - REN34. Circuit breaker SF1 - BA47-29. Fan M1 - dimensions 120x120x32 mm, for a rated voltage of 48 V (current consumption - 0.25 A), for example, D1238E48B or EFB1248HF. M2 fan - for a voltage of 12 V (at a current of 0.15 A) with dimensions of 80x80x20 mm from a computer PSU. Measuring devices RA1, RA2 - M42300 with a total deflection current of the needle 1 mA and 1 A, respectively.

Capacitor C1 is a two-three-section KPI from a broadcasting receiver (the gap between the rotor and stator plates is at least 0.3 mm). All sections of the capacitor are connected in parallel. Anode KPI C31 - from the UHF-66 physiotherapy device (one section was used), the gap between the inserted rotor and stator plates is at least 0.8 mm. Capacitors C15-C17, C29, C30 - KVI-3 and K15 series. Blocking capacitors - KSO or K31-11. Trimmer capacitors C12 and C13 - KPK-MP. All oxide capacitors are imported.

Capacitors of the high-voltage rectifier C25 and C26 - K75-40b 100mkFh2kV. They can be replaced by ten oxide capacitors with a capacity of 470-680 microfarads for a nominal voltage of 400-450 V, connected in series. To equalize the voltage, each capacitor should be shunted with a MLT-2 220 kΩ resistor.

The SA1 switch was used from the R-130 radio station, which has undergone modernization: a common silver-plated current collection contact has been introduced, after which the switch can withstand a power of 2 ... The biscuits are axially connected to the switch housing, which made it possible to switch additional capacitors on the 1.8, 3.5 and 7 MHz bands.

Most of the resistors in the amplifier are MLT or CF-2W. Resistor R44 - non-inductive TVO-10. All tuning resistors - SPO-0.5, SP4-1A. Thermistor RK1 - MMT-4.

Halogen lamp EL1 - 250-500 W/220 V, 8 mm in diameter and 78...115 mm long. The lamp is installed in a regular ceramic holder on the reverse side of the front panel of the amplifier. To see its glow, a hole with a diameter of 3 mm was drilled in the panel.

Indicators HL1-HL3 - imported neon N-814 for 220 V, red, green and blue glow. LED HL4 - imported, blue glow.

Transistors VT1, VT4, VT5 are installed on heat sinks with an area of ​​25 cm 2.

Most parts of the amplifier are mounted on printed circuit boards. The power meter board is attached to the pins of the XW2 connector, and the axis of the tuning resistor R49 (calibration of the PA1 readings) is displayed on the rear panel "under the slot" next to the connector.

The primary adjustment of the amplifier is carried out without connecting the anode transformer T1 to the network and disconnecting its winding II from the rectifier, as well as disconnecting the winding II of the transformer T2 from the rectifier. First, they check the presence of voltage sources of +48 V / +24 V and the incandescence of GK-71 lamps, then they check and adjust the operation of automation units and select the optimal operating modes for the fans. By heating the thermistor RK1 to a temperature of 100 ° C, the trimming resistor R13 sets the threshold for a sharp increase in the number of revolutions of the fans. The maximum speed of the fans is set by a trimming resistor R19, the minimum is R17. The resistance of the resistor R51 is chosen so that the voltage on the M2 fan does not exceed + 13 V in the "TX" mode. To check the operation of automatic protection, a voltage of +24 V is applied to the base of the VT4 transistor through a 22 kΩ resistor (without turning off the remaining circuits) and the threshold for a clear operation (shutdown) of relay K3 is set with a trimmer resistor R28.

GK-71 lamps, especially those that have been out of work for a long time, should be subjected to "training" by keeping them under filament voltage for 12 ... 20 hours, after which the emission of the lamps, as a rule, is restored.

Next, the winding II of the transformer T2 is connected to the rectifier and the operation of the voltage regulator of the first grid is checked. The bias voltage must be regulated by a trimming resistor R22 in the range of -90 ... -130 V at a current of 8 ... 10 mA, which is measured at the contacts of relay K1.2. Then the transformer T1 is connected to the network and the voltage on the screen grids of the lamps is measured, which should be +650 ... + 700 V. If necessary, they phase and select the taps of the winding II of the transformer T3 according to the best voltage stabilization of the second grid.

And lastly, OBSERVING THE PRECAUTIONS, check the high voltage rectifier. First, a voltage of 270 V is applied to it from winding III and the voltage distribution across the capacitors is measured. Only after that is the full voltage applied from the high-voltage winding I of the transformer T1. The voltage at the rectifier output should be 3100 ... 3300 V without load, and under load of 0.6 A - 2900 ... 3000 V.

If all voltages are normal, the amplifier is switched to the "TX" mode and the quiescent current of the lamps is set within 140 ... 150 mA.

It is extremely important to check the amplifier for the absence of self-excitation in the "Setting" and "Operation" modes, as evidenced by sharp jumps in the quiescent current and the operation of automatic protection in all ranges and at different positions of the rotors of capacitors C1, C31. As an indicator of self-excitation, it is convenient to use an MN-3 neon lamp fixed on an insulated stick, bringing it to the elements of the videoconferencing system. Only after the elimination of self-excitation, if any, you can proceed to further tuning the MIND.

The input circuits and the low-pass filter are tuned by selecting the number of turns of the T5 transformer and adjusting the capacitors C12, C13, achieving a uniform buildup of the lamps in all ranges (especially in the 28 MHz range) with a signal power from the transceiver of 15 ... 20 W.

By connecting to the output of the amplifier a load equivalent of 50 (75) Ohm with a power of 1 ... 2 kW, and to the case - a protective ground, a signal with a power of 5 ... 10 W from the transceiver is fed to the input of the amplifier. The P-loop is tuned in the HF bands by selecting the taps of the L1 coil, starting in turn from the 28 MHz range. The capacitance of the capacitor C31 should be
to be close to the minimum. On the 14 MHz band, the entire coil winding is used. Then, by selecting the taps of the L2 coil and capacitors C15-C17, the P-loop is tuned in the low-frequency ranges.

The output power meter can be adjusted without connecting the amplifier to the network. It is enough to apply a 100 W signal from the transceiver to the PA input and connect the equivalent of 50 ohms instead of the antenna.

Having finished the preliminary tuning, a signal with a power of 20 ... 30 W is fed to the PA input and the VCS is adjusted again. With an output power of 1 kW, the anode current can reach 550...600 mA.

Publication date: 03.07.2018

Readers' opinions

• Vladimir / 10.07.2019 - 08:33
  my e-mail [email protected]
• Vladimir / 10.07.2019 - 08:30
  is it possible to write off about the repetition of the mind on 2 GK71

UM on GK71 with OS

The PA is made on a GK71 lamp, an “old” reliable one with graphite anodes that does not require airflow. Scheme Classical, with OS, at Eg. Anode-3kv,Screen. Grids-50v, Glow-22v (in "SLEEP" mode-11v) and Quiescent Current-100mA. Rvx-50-80vt. Rout (at Eq. 50 ohm) -500-700W. A feature of the UM scheme is: Introduction cx. Protection against current overloads and short circuit. The introduction of "SLEEPING" mode in the MIND. For better coordination with IMPORTED transceivers, the use of a "CATHODE" resonant circuit. ORIGINAL cx. "P"-circuit, allowing you to get the SAME Pout. on all ranges.

The power supply of the PA is carried out from one powerful TR-RA, made on the TOR. High Anode voltage (2.5-3.0 Kv), is obtained after rectifying-doubling the voltage taken from the step-up winding of the Tr-ra. When the PA is turned on, the mains voltage 220V passing through the F1 Surge Filter, the VA-47 Circuit Breaker, is supplied to the primary winding of the Tr-ra through the L3 HALOGEN lamp, which ensures “SOFT” switching on, prolongs the life of L1-GK71 and other elements of the PA. After the capacitors are charged, part of the high voltage taken from the divider (R 1-R 8 and potentiometer R 10) is fed to the AUTOMATIC circuit on VT 3, and if there is no short circuit in the PA circuit, the voltage is normal-VT 3 opens, Relay P4 is activated, closing the lamp L3 with its contacts KR4. A feature of this AUTOMATIC circuit is the “SMALL HYSTERESIS” of actuation-release P4, which provides reliable protection of the PA from various overloads: by the ANODE current, short circuit in the secondary circuits, Breakdown and short circuit in the Tr-ra windings at which VT 3 closes, P3 is de-energized and the mains the Tr-ra winding is connected to the network through L3, preventing the failure of the PA elements.

In the “STANDBY MODE”, an INCOMPLETE filament voltage, 11v, is supplied to the L1-GK71, this ensures a low heating of the lamp and the PA as a whole and the “SLEEP” PA mode. When switching to "TX", the full filament voltage (22v) is applied to the GK71 and already after 0.2-0.25 seconds the PA is ready to operate at full power, which is the undoubted advantage of direct incandescent lamps (GK71, GU13, GU81).

For a more complete alignment of the UM with the IMP. By transceivers, a "CATHODE LOOP" is used, tuned to resonance on each Range, by connecting Capacitors to L 1 using Relay P7-24. Initially on Diap. 28 MHz L 1 is tuned by tuning C 28. On the low bands (1.8 and 3.5 MHz) for more complete matching, due to the narrow band of the "CATHODE LOOP", the signal through the contacts of Relay P9 is fed to the "CATHODE THREE WINDING CHOCOLATE" - DR1 , while "L 1" to eliminate the influence, short-circuited by RF, capacitor C2, through the contacts P11-KR11. The SWR at the PA input does not exceed 1.5 on all bands and is PERFECTLY consistent with ANY IMPORTED Transceiver, even without a TUNER.

The output "P" circuit of the PA is switched by a 4x paid switch: The first board - switches the taps of the coils, the second - SHORT 1.8 MHz coil (or 3.5 MHz, if the 1.8 MHz band is NOT planned). The third one connects additional Capacitors for "COLD" KPI on range. 1.8 and 3.5 MHz. The fourth one switches Range Relays. The “L 28” coil operates on the 28 MHz range, which is located directly in the GK71 anode circuit, which made it possible to obtain Pout at 28 MHz the same as on the low bands! DR 2 - is necessary for the PROTECTION of the output circuits of the MIND.

“RX-TX” is controlled by a circuit on VT 1, which is powered by Eg. +24v. When the “TX” input is closed to the Case (current 3-5mA), VT 1 opens, Relay P6 is activated, and through contacts KR6 voltage + 24V is supplied to Relay P1 and R2, Relay -P5 is activated, supplying full Eg. Glow on GK71 (If the “NAK” switch is on, the FULL VOLTAGE of the GUN on L1 is constantly supplied, which is necessary when working in the “TEST”). AND LATER, after charging the capacitor C1, after 0.15-0.2 seconds, the Relay P3 will work (this ensures the "CORRECT" operation of the PA, the absence of burning of the relay contacts P1, P2) and with its contacts KR3 closes the circuit C1 of the lamp L1 to the housing, opening her. To implement the "BYPASS" mode (switch "RA" in the lower position), the + 24V supply circuit of the circuit is broken at VT 1 of the "RX -TX" switch. On VT 2, an adjustable voltage regulator C2 is made, adjusting R 11 - they set the CURRENT REST L1, within 100-120mA. On "MC1" a voltage regulator + 24V is made to power the Relay and cx. Automation. In case of overloads and short circuits at + 24V, "MC 1" is automatically turned off, which also increases the reliability of the PA as a whole.

DESIGN.

UM is made in COMP. Case (preferably "OLD-80s" made of thick steel) Gab: 175-W 325-H 400mm-Dep. The vertical partition and horizontal shelves are made of steel, 1.5-2 mm thick. With INTENSIVE PA work, it is desirable to use a fan operating at a reduced supply voltage so that it DOES NOT MAKE NOISE.

DETAILS.

In UM applied: TR 1 is made on IRON from LATR-8-10a. Network winding - wire -1.5mm, Step-up -0.65-0.7mm Eg. ---1.1-1.2kV. Filament exchange ---1.5mm 11+11v other obm. -0.5-0.65mm for e.g. -22v and 50v. The cathode choke DR1 is wound with a 1.2-1.5mm wire into two wires on a ferrite ring K 45 + 27 + 15mm 2 000NN, and contains 12 turns, cat. Connections --- 7 turns of MGTF-0.2 wire, evenly distributed between the turns of the main winding. "L 1" of the CATHODE CIRCUIT is made of a copper tube, Diam. 5-6mm, inside which a wire is stretched in heat-resistant insulation (MGTF, BPVL, etc.) with a cross section of at least 1mm. The outer diameter of the coil is 27-30mm, the gap between the turns is 0.2-0.3mm and contains 8 turns, a tap from the middle. "L 28" is made of copper exchange. Wire Diam. 2.0-2.5mm and contains 5-6 turns, the outer coil diameter is 25mm. ANODE THROTTLE DR -- fluoroplast Diam. -18-20mm, 180mm long, wound with PELSHO-0.35 wire, turn to turn in sections 41 + 34 + 32 + 29 + 27 + 20 + 17 + 11 turns and the last 10 turns IN DISCHARGE with a step of 2 mm.

"L 10-21" is made of copper tube Diam. 5-6mm and contains 15-17 turns, outer Diam.-50-55mm. "L 1.8-7" is made on the frame Diam. 40-45mm and contains 15+ 12 turns of wire 1.5-2.0mm (the first 15 turns are wound turn to turn - this is for Range. 1.8 MHz, and the remaining 12 turns with a pitch of 2.5 mm. DR 2 --- Winding "UNIVERSAL "wire 0.2-0.3mm 2-4 sections of 80-100 turns. F 1-wound on the ring K 45/27/15mm2000NN in two wires Dia. 1mm with good insulation (MGTF), turn to turn until filled.

Anode KPI from UHF-66 (one section, gap 2.5-2.7mm 15---100pf, connected to the 2nd turn), KPI "HOL," - 2-3Sec. From "Old" radios with a gap of 0.3 -0.4 mm, 30---1200pf.

Relay: R 1 --- REN-33. R 2-REN-34. P 3,4,5,6 --- IMP. m/gab (15/15/20mm) per slave Eg.-12v Switching current-6-8a\125-220v. in plastic housings. R 7, 9, 10, 11, 14, 18, 21-RES -10.

Transistors: VT 1 --- KT 835, KT 837. VT 2, VT 3 --- KT 829A. MC ---KR 142 EN-9I or 78L 24.

Vyacheslav Fedorchenko (RZ3TI).

We lived, we didn't grieve
Two nesting dolls, two lamps,
Not some insects, but gekas,
Seventy-one, cuties.
(S.S. Gribovsky)

So they would have lived for themselves, had not fallen under my hands. Moreover, the scheme taken as a basis caught my eye:

This determined their future fate. I decided to assemble this miracle device. I set myself the task of using the available components whenever possible and thereby reducing the cost of the design. Basically, he did everything according to the author's description, but refused to use expensive B1V vacuum contactors, using a biscuit switch, converted according to Benzar, to switch the taps of the P-circuit coils, and used the variometer coil from RSB-5 bl.3 as L8. The anode choke is designed and made according to RV4LK, the cathode choke is wound on a core from a fuel assembly with a permeability of 3000nm. To connect an additional capacitance to the hot end for a range of 160m, a clapperboard relay from RSB-5 was used. Power transformer from the apparatus of medical equipment IKV-4 (weak in terms of power). The output relay TKE56POD is installed on the foam to reduce the audibility of operation clicks. The power supply (assembled in a case from a minitower computer) and the amplifier itself are made in different cases, based on the location conditions in the shack. KPI adjustment knobs for 10 and 8 mm - from the lids of cosmetics jars. To simulate the arrangement of elements in the body with given dimensions, I used the AUTOCAD program. The result of creativity in the photo below.
Amplifier (535x320x185mm):

Power supply (175x400x335mm):

73 and success in your work!
RA2FN, Sergey.

Working on bugs:

Six months later, the P-circuit switch, made according to Benzar, burned out. Instead, I installed a modified ceramic switch from RSB-5 (I used a movable group of contacts from two identical switches). It turned out a good contactor for 6 positions with self-cleaning contacts. 3 years - normal flight.
Also, I had to abandon the use of the TKE relay in the bypass circuit. Bulky and very noisy, and the response time is too long for the QSK mode. I installed a reed contact with a self-made winding for switching the output. It turned out a reed relay (works in tandem with RES-48 at the input). Works fast, quietly, reliably. There have been no failures in three years.
In the power supply, I replaced the previously used (and died in the anode circuit) diodes KD202R with imported 10A7. Good, powerful diodes. You can, and even better, use 10A10.
19.11.2014RA2FN, Sergey.

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