The simplest QRP transceiver. CW QRP direct conversion transceiver with seven transistors (15m)

Of course, an ordinary high-frequency n-p-n transistor of the type KT603, KT646, KT606 can also be used in the circuit, but a powerful field-effect transistor works more stably, is less susceptible to the effect of direct signal detection and allows you to increase the output power of the transceiver. The local oscillator frequency is stabilized by a widely used quartz resonator at a frequency of 3579 kHz. You can also use a ceramic resonator.

A variable capacitor allows you to shift the frequency within a small range, which makes it easier to tune in to the called station. When using a quartz resonator, the frequency can be shifted by 1.5-2 kHz. If you use two or three quartz connected in parallel, then the frequency can be changed up to 4-5 kHz.

When ceramic resonators are used, the frequency tuning range is several tens of kilohertz.

In receive mode, the signal from the antenna passes through a low-pass filter L1L2C5C6C7, then through a 1:4 matching transformer, and enters the drain of the transistor. The resistance of the field effect transistor channel changes with a frequency determined by a quartz resonator. As a result, the difference frequency signal between the receiving and generated frequencies is separated on the resistor R3.

Through the coupling capacitor C9, it is fed to the audio frequency amplifier. It can be made on 2-3 transistors or a chip like LM386. At the ULF input, it is desirable to use a low-pass filter (narrow-band or low-pass), this will significantly increase the selectivity of the receiver.
When you press the telegraph key, the transistor switches to amplification mode. The transformer provides matching with a 50-ohm load (antenna), and the low-pass filter provides filtering of harmonics in the emitted signal. The output power can reach 6 watts, and the current consumed from the power source can be up to 1 ampere.

The high-frequency choke must be rated for a current of at least 1 ampere.
The matching transformer can be wound on a ferrite ring with a diameter of 12-16 mm with a permeability of 600-1000. Winding is carried out with two pre-twisted wires 0.4 mm, twist pitch 10-12 mm. The number of turns is 10.

After winding, the end of the first winding is connected to the beginning of the second and soldered to the drain of the field effect transistor.
It is also desirable to wind coils L1 and L2 on ferrite rings of the 20VCh or 50VCh type with a diameter of 10-12 mm.
The field effect transistor must be installed on the radiator through a mica gasket.

The image below shows possible variant assembled CW transceiver.

As you can see in the photo, the transceiver has a field indicator in the antenna. It is not difficult to do this on several details (Fig. 1, Fig. 2). The transformer is wound on a 20x10x5 ring with a magnetic permeability of 1500-2000. Transformer T1 consists of a loop coil (5 turns *) and a coupling coil (2 turns *).

Igor Grigorov (RK3ZK)
Radio 12-2000

This transceiver was designed to operate on the air on camping trips, but it can also be used as a stationary on a QRP radio station. A feature of this device is a reduced supply voltage, which allows using two galvanic cells instead of a traditional battery.

To power almost all stages of the QRP transceiver, a power supply of several volts is sufficient. The exception is the transmitter power amplifier, from which an acceptable output power and good efficiency can only be obtained at voltages of 10 V and above. In the proposed QRP transceiver, this contradiction is resolved by introducing a 3/12 V voltage converter into the design, which made it possible to use two galvanic cells to power it. Tests of the device showed that a set of two R20-type elements allows you to work on the air for 5-7 days for 2-4 hours. The operability of the transceiver was maintained when the supply voltage was reduced to 2.2 V.

The transceiver is designed to work as a telegraph on the amateur bands of 160 and 80 meters. It is made according to the scheme of direct frequency conversion. The sensitivity of the receiving path at a signal-to-noise ratio of 10 dB is no worse than 2 μV. The power given by the transmitter to the load with a resistance of 50 ohms is not less than 0.5 W. The current consumed by the transceiver in the receive mode does not exceed 200 mA, and in the transmit mode - 800 mA. Dimensions of the device - 245 x 110 x 140 mm, and weight - about 1.5 kg

The block diagram of the transceiver, combined with the interconnection diagram, is shown in fig. 1. It consists of five blocks A1-A5. The XS1 jack is used for connecting wire antennas, and the XW1 high-frequency connector is used for antennas powered by coaxial cable, as well as for working with an external power amplifier. The serial circuit L1, C1 allows you to match the output of the transmitter with antennas having an input impedance of 15 ohms to 1 kOhm. Diode bridge VD1-VD4, resistor R1 and measuring device PA1 form an RF milliammeter that controls the current in the antenna in transmission mode.

The schematic diagram of block A1 is shown in fig. 2. In the receive mode, the signal from the antenna through the contacts of the SA1.1 switch (see Fig. 1) and output 1 of this block is fed to a two-circuit band-pass filter 1L1, C1.1, C3, 1L2, C1.2, tunable in frequency band 1 ,5...4 MHz. Then, through the source follower on the transistor 1VT1, the signal is fed to the ring mixer (1T1, 1T2, 1VD1-1VD4). Through output 3 of the block, the local oscillator voltage is supplied to the mixer from block A4.

The audio signal after the mixer highlights the low-pass filter 1C11, 1L4, 1C12 with a cutoff frequency of about 3 kHz. Through pin 6, it enters block A2. Power (+3 V) is supplied to the source follower through pin 7. A resonant amplifier doubler of the local oscillator signal is made on the 1VT2 transistor. The circuit 1L3, 1C1.3 in the range of 160 meters is tuned to the fundamental frequency of the local oscillator, and in the range of 80 meters - to its second harmonic. From the 1VT2 collector, the signal goes to the emitter follower on the 1VT3 transistor, and from it, through pin 5, to the A4 driver-amplifier unit. The cascades on transistors 1VT2 and 1VT3 are supplied with a voltage of +12 V through pin 4. The placement of these cascades on the same board with the input stages of the receiving path is due to the fact that both of them are tuned in frequency by one KPI block (1C1).

In block A2 (Fig. 3) there is a low-frequency amplifier, a "sideband" selection key during transmission and a telegraph signal self-control generator. As a ULF, a board from an audio player of the "ARTECH-WM15-EQ" type was used, which is supplemented with a 2T1 output transformer. The transformer made it possible to reduce the current consumed by the amplifier and limit its frequency response. With a supply voltage of +2...3 V, the amplifier provides output power sufficient for a small dynamic driver or headphones with a resistance of 16 ohms. The player's volume control was removed from the board and replaced with a variable resistor (see R5 in Fig. 1), which is placed on the front panel of the transceiver. It is connected to block A2 (terminals 7, 8, 9) by wires enclosed in a shielding braid.

An inverter is made on the 2VT1 transistor, which is used to control the local oscillator frequency shift in transmission mode (shift up or down). In direct conversion transceivers that receive both sidebands at the same time, this can be useful in certain situations. The voltage that controls the local oscillator frequency shift is supplied to the local oscillator unit (A3) either from the power bus of the transmitting stages (i.e., when switching to transmission), or through an inverter on the 2VT1 transistor from pin 3. The choice of operation is made by switch SA3 (see. Fig. 1).

Since the receiving path is disabled in the transmission mode (the +3 V supply voltage is removed from terminal 7 of block A1 and output 5 of block A2), the transceiver uses a telegraph signal self-control circuit using an audio frequency generator - a multivibrator based on transistors 2VT2, 2VT3. The generator signal with a frequency of about 1 kHz is fed through an emitter follower on a 2VT4 transistor into the primary winding of the ULF transformer. The supply voltage to the generator is supplied through terminal 4 from block A4 only when the telegraph key is pressed.

The GPA scheme (block A3) is shown in fig. 4. The master oscillator is assembled according to the capacitive "three-point" scheme on the transistor GT313B (3VT1). It is this type of germanium transistors at a supply voltage of +2 V that made it possible to obtain the best frequency stability and the least distorted output signal shape. The frequency-setting circuit is formed by a 3L1 coil and capacitors ZC1, ZS2, ZS5, ZS6. The generator generates an RF voltage with a frequency of 1750 ... 1850 kHz for a range of 80 meters and 1830 ... 1930 kHz for a range of 160 meters. The 3VT4 transistor is a local oscillator signal amplifier. The local oscillator supply voltage stabilizer is made on elements 3R13, ZS10, 3VD1-3VD3.

The switching of the subranges of the generator is carried out by the SA5 switch (see Fig. 1). When switching to a range of 80 meters, a voltage of +3 V will be applied to terminal 1 of block A3, the 3VT2 transistor will open and connect an additional capacitor 3C4 to the frequency-setting circuit. The local oscillator frequency will decrease. The key on the 3VT3 transistor connects the 3C7 capacitor, shifting the GPA frequency in the transmission mode. As already noted, the control signal comes through pin 2 from block A2 (pin 3). On 160 meters the offset is 400 Hz and on 80 meters it is 800 Hz. This is quite acceptable when working by telegraph.

When changing the range, it is necessary, of course, to rebuild the capacitor C1 (according to the signal level of the received stations or to the maximum output of the output stage). The local oscillator voltage is fed through pin 3 of the block to block A1 (pin 2), where it is amplified or doubled (see above) and then to pin 2 of block A4.

Block diagram A4 is shown in fig. 5. Transistors 4VT2, 4VT3 amplify the local oscillator signal to a level sufficient for the operation of the ring mixer of the receiver and the buildup of the output stage of the transceiver on the transistor 4VT4. A matching transformer 4T1 is included in the collector of the 4VT4 transistor. Power is supplied to the output stage of the transmitter through a key on the 4VT1 transistor only during manipulation. The key is connected to pin 6 of this block.

The voltage converter 3/12 V (block A5) is made according to the scheme of a push-pull generator with transformer connection. Its scheme is shown in Fig. 6.

The transceiver uses fixed resistors of the MLT type. Variable resistor R5 (see Fig. 1) - type SP-1 (dependence B). Permanent capacitors - KM (in GPA), KD, KLS, K10-17, oxide capacitors - K50-35, K53-14. The variable capacitor 1C1 in block A1 is a standard three-section KPE-3 from the Melodiya-104 radio receiver or from Rigonda type tube receivers. The tuning capacitor ZS1 in the GPA is made of a tuning capacitor with air insulation KPV-50. Capacitor C1 - KPE-2 (2x12 ... 495 pF), in which both sections are connected in parallel. The inductors in blocks A1 and A3 are wound turn to turn with PEV-2 0.35 wire on frames with a diameter of 6 and a height of 20 mm. The number of turns is 22. The coils have trimmers with a diameter of 2.8 mm made of ferrite with a permeability of 600 (used in the IF circuits of transistor receivers). The inductor L1 of the output stage contains 34 turns of PEV-2 0.5 wire. It is wound on a frame with a diameter of 20 mm. Winding length - 24 mm. The magnetic head of the player was used as a low-pass filter coil 1 L4 (block A1).

The mixer transformers are wound with PEV-2 0.12 wire on ring ferrite magnetic cores (600NN) of size K10x6x5 mm. The number of turns is 3x25. The transformer 4T1 of the power amplifier is wound on a ring ferrite magnetic core 2000NM, size K17.5x8.2x5 mm. The number of turns is 2x10, the PELSHO wire is 0.31. Transformer 2T1 to ULF - output from the Alpinist transistor receiver.

The voltage converter transformer is wound on a ring ferrite magnetic core (2000NM) of size K17.5x8.2x5 mm. The primary winding contains 2x12 turns of wire PEV-2 0.18, the secondary - 48 + 10 + 48 turns of wire PEV-2 0.3. The secondary winding is located on top of the primary evenly around the perimeter of the ring.

Most of the transceiver parts are placed on five boards made of double-sided foil fiberglass. Board dimensions: A1 - 100x90 mm, A2 - 200x40 mm, A3 - 80x70 mm, A4 - 95x35 mm, A5 - 60x40 mm. The foil on one side of the boards is kept as a screen. The installation is carried out on the second side on the patches of foil, which are cut through at the place of installation of the parts. Of course, it is possible to assemble the transceiver on a single board. The GPA A3 block is enclosed in a screen, also soldered from foil fiberglass. The 3VT4 transistor is equipped with an aluminum radiator measuring 20x20x4 mm. Converter transistors 5VT1, 5VT2 also have small radiators - copper plates measuring 15x15x5 mm.

The transceiver is assembled in a case made of foil fiberglass. An approximate arrangement of blocks in the transceiver is shown in fig. 7. By using miniature switches, small-sized variable capacitors, the size and weight of the transceiver can be significantly reduced.

When working in the field on a range of 80 meters, communications were made over a distance of up to 500 km, and communications up to 300 km were made on a range of 160 meters. The work was carried out on a wire antenna 41 m long. The transceiver proved to be a fairly reliable device that maintained frequency stability and output power when the batteries were discharged.

Experiments were carried out on powering the transceiver from two batteries of the NKGTS-1.5 type. With constant recharging of the batteries by a small solar battery, delivering a maximum current of 40 mA, work was possible up to 14 days from one full charge of the batteries for 3-4 hours a day.

The simplest QRP transceiver

QRP CW/DSB transceiver circuit from PA3ANG to TCA440 (K174XA2) Output power of the transceiver is about 3 watts

Actual PCB size 89 x 46 mm

QRP CW transceiver from DG0SA

Radiohobby 2006 #2

CW QRPP Elfa-2

Sensitivity - 80uV output power - 0.5W

UU80b by G3XBM

Another version

YOUR FIRST TRANSMITTER

Ya.Lapovok (UA1FA)

The operating frequency range is 160m (depending on the applied quartz), the maximum current is 400mA, the output power is 2 ... 3W

Literature: magazine "Radio" 2002 No. 8

CW direct conversion transceiver

This transceiver is designed to work as a telegraph in the amateur band of 80 m. The generator with quartz frequency stabilization, assembled on a VT5 field-effect transistor used both in the receiving and transmitting paths and performs, respectively, the functions of either a local oscillator or a master oscillator. The quartz resonator is connected to the XS4 socket. Within small limits (depending on the parameters of the resonator and the elements of the circuit L1C12), the operating frequency of the generator can be changed by a variable capacitor C12. Usually it is not difficult to "shift" the generator frequency by 2-3 kHz.

From the circuit L2C13, through the coupling coil L3, the radio frequency voltage enters the base circuit of the transistor of the output stage VT4. The manipulation is carried out in the emitter circuit of this transistor with a key connected to the XS3 socket. The output circuit L5C9 is matched to the collector circuit of the transistor VT4 and the load (antenna) coupling coils L4 and L6. Transistor VT4 operates without initial bias (in mode C).

The receiving path of the transceiver is assembled according to the direct frequency conversion scheme. When the key is not pressed, the VD1 diode is opened by a current determined by resistors R9 and R8. The signal from the antenna, received through the coupling coil L6 in the circuit L5C9, passes freely into the circuit of the first gate of the field-effect transistor VT3, which operates as a mixing type detector. The RF voltage of the crystal oscillator is applied to the second gate through the SI capacitor. The bias voltage at this gate determines the divider formed by resistors R10 and R11. The variable resistor R8 performs the functions of a signal level regulator in the receiving path.

The audio frequency voltage released on the primary winding of the transformer T1 is amplified by a two-stage amplifier based on transistors VTI and VT2. The load of this amplifier is headphones with a resistance of emitters of 1600-2200 Ohms, connected to the XS1 socket. To increase the volume of radio signal reception, the emitters are connected in parallel.

The coils of the LI-L6 transceiver are wound on frames with a diameter of 6-8 mm (from television receivers) with carbonyl iron trimmers. The windings are made of copper wire with a diameter of 0.3 mm in enamel insulation. The number of turns of the coil L1 - 60, L2 and L5 - 50 each, the rest - 12 turns each. Communication coils (L3, L4 and L6) are wound over the corresponding contour coils, the winding is ordinary, solid.

As a transformer T1, a matching transformer from a transistor broadcasting receiver was used. Capacitor C12 should have a maximum capacitance of approximately 400 pF and possibly a lower initial capacitance.

The establishment of the transceiver begins with the transmitting path. An antenna equivalent is connected to the XS2 socket - a resistor with a resistance of 75 or 50 Ohms and a dissipation power of 1 W. By temporarily short-circuiting the coil L1 and setting the rotor of the capacitor C12 to the position corresponding to the maximum capacitance, the adjusted capacitor C13 achieves the maximum emitter current of the transistor VT4 (a control milliammeter with a full deviation current of 200-250 mA can be connected, for example, to the XS3 socket). Then, the trimmer capacitor C9 achieves the maximum radio frequency voltage on the antenna equivalent. The current consumed by the output stage should be about 150 mA. If the output power of the transmitter is noticeably less than 0.7 W, the number of turns of the coupling coils should be selected (primarily L4 and L6).

When setting up the receiver, it makes sense to select the R10 resistor and the SI capacitor according to the maximum sensitivity of the receiving path. In the audio frequency amplifier, resistors R2 and R3 are selected according to the voltages on the collectors of transistors VT1 and VT2 (respectively 2-3 and 5-7 V). Transistors VS109 can be replaced with KT342, KT3102 and similar ones; 40673 - on KP350; BF245 - at KPZ0Z or KP302; 2N2218 - on KT928; diode 1N4148 - on KD503 and similar ones.

QRP CW transceiver at 7 MHz

Output power 500mW

Polevik-80 transceiver

Technical characteristics of the Polevik-80 transceiver:

Supply voltage 10 - 14 V

Current consumption (at 12V)

– in receive mode 15-20 mA

– in transmission mode 0.5 – 0.7 A*

Frequency range: 3500 - 3580 kHz**

Sensitivity (at 10 dB S/N): approx. 10 µV

Output power: 3W*

* - depends on the antenna matching circuit;

** - depends on the overlap of frequencies by the local oscillator.

If necessary, this transceiver can be converted to other ranges. On the HF bands, special attention should be paid to the quality and stability of the local oscillator and mixer.

In receive mode, the signal from the antenna through the low-pass filter to L2, L3, C3, C6, C8, C9 is fed to a field-effect transistor mixer (hence the name of the transceiver) VT3, VT5. The source-drain junctions of the transistors are connected in parallel, and the anti-phase voltage of the local oscillator is applied to the gates through the transformer T1. For one

period of the heterodyne voltage, the conductivity of the transistors changes twice. In this case, the signal is converted: F = Fsig ± 2Fosc.

The local oscillator operates at a frequency 2 times lower than the received one. As with back-to-back diode mixers, this is advantageous for several reasons: a low operating frequency LO has less frequency drift, and its harmonics are suppressed by the input filter. The low-frequency low-pass filter L4, C11, C12 emits an audio signal, which is amplified by a two-stage VLF on transistors with a high current transfer coefficient. As headphones, you can use high-impedance phones or a low-impedance headset with a matching transformer (Fig. 1).

The local oscillator is made according to the classical Hartley circuit on a VT1 transistor and has no features. The buffer stage (VT2) serves to decouple the local oscillator.

Choice for high power FET mixer RD15HVF1,

designed for RF and microwave amplifiers, is dictated solely by their good parameters and availability. Having a small gate capacitance, they slightly load the local oscillator, which increases its stability. Transitions of transistors RD14HVF1 begin to conduct at a gate-source voltage of +3 ... 4 V. In the receive mode, the DC sources of transistors VT3, VT5 are disconnected from the "ground" through the closed transition of the control transistor VT4, but are closed in alternating current through the capacitor C11. In this case, field-effect transistors VT3, VT5 behave like controlled resistances and have

high linearity.

In transmission mode, when the key S1 is pressed, the control transistor VT4 opens, which closes to ground

low-frequency path of the transceiver and passes through itself the source currents of the mixer of considerable magnitude. Through

transformer T2 to the mixer, which now plays the role of an amplifier-multiplier, is supplied with a supply voltage. And through the capacitor C9, the transmitter signal enters the matching

to match the low output impedance of the FETs with the antenna impedance. When mounting HF transistors RD15HVF1, the length of the connecting conductors should be minimized and shielding should be provided. This will help to avoid self-excitation at RF, as well as reduce the level of spurious emissions. Transistors VT1, VT2 can be replaced by other low-power RF field-effect transistors with a small cutoff voltage. Instead of RF transistors VT3 and VT5, you can use other field-effect transistors with as little as possible

gate capacitance, such as BS170. If you use the widely used IRF510 field device, then due to the significant gate capacitance, the local oscillator buffer stage on VT2 will be heavily loaded, and the voltage across the transformer T1 will not be enough to operate the mixer. In this case, you will have to add another amplification stage to the local oscillator. Instead of the control transistor VT4, you can use a powerful

switching "field" of another type, for example IRF630. ULF transistors VT6, VT7 should be selected according to the maximum current transfer coefficient h21e (it must be at least 800).

Inductors can be wound on existing frames with a diameter of at least 6 mm. Specific inductance values ​​are selected when matching the RF circuit. Transformers T1 and T2 are wound on toroidal cores with a permeability of 1000 ... 2000 with a thick wire folded three times in insulation

(for example, a core from a UTP cable used for laying computer networks is suitable). The winding contains 5 ... 8 turns. The middle terminal of the symmetrical winding of the transformer T1 is obtained by connecting the beginning of one winding to the end of the other. All three windings of transformer T2 are connected in the same way. As a matching low-frequency transformer, you can

use a transformer from a "radio point" or from an old radio.

It is better to power the transceiver from a battery, then a possible alternating current background will not interfere with reception.

Setting up the transceiver comes down to setting the ULF operating mode with resistor R7, while the voltage at the VT7 collector should be close to half the supply voltage. By adjusting the core of the L1 coil, the local oscillator is “driven” into the desired range. During normal operation, the RF voltage at the gates VT3, VT5

should reach 4 ... 5 V at the peaks. By connecting its equivalent instead of the antenna, and pressing the key, adjust the output low-pass filter, achieving maximum power at the antenna equivalent. The effective voltage value (Vrms) is 12.1 V, which at

50 ohm load corresponds to almost three watts (3 W). By improving the coordination, you can increase the efficiency and even get QRP

transceiver! (two RD15HVF1 transistors are able to "give" to

antenna up to 36 W!). In the process of developing and setting up this transceiver, I had one funny incident: when the ULF was not yet soldered on the layout, I connected L4, C11, C12 to the low-pass filter

21headphones, and to the antenna connector - a shortened vertical by 80m, and late at night, when everyone was sleeping, in a quiet room I heard signals from amateur telegraph radio stations from the headphones! If you listened, you could recognize both distant lightning strikes and very faint background noise.

interference. And all this even without ULF! It turned out a kind of "detector direct transformation". Dmitry Gorokh UR4MCK

Y. Lebedinsky UA3VLO

QRPP transceiver "Komarik" and my experiments with it.

Until recently, I was very skeptical about the possibilities of QRPP on low-frequency bands. I had to work with a power of 5-10 watts, because in the seventies, when I started working on the air, it was commonplace. But to work with a power of less than one watt, and even on the simplest home-made transceivers such as "MICRO-80", "PIXIE" with an output power of 0.3 - 0.5 watts, he considered it a frivolous matter. The designs of such transceivers, found on the Internet, were often placed in soap dishes, telegraph keys, and even in tin cans, which looked more like a souvenir toy than a working device. And the results of work on them, found on forums on the Internet, did not inspire much optimism. Therefore, when I decided to try a crystal oscillator with a frequency shift in such a transceiver as a GPA, I did not have much hope.

By experimenting with a FET crystal oscillator with two quartz resonators in parallel (such oscillators are sometimes called "Super VXO"), and adding an inductor and a variable capacitor to the resonators in series, I was able to achieve frequency tuning down 40 - 60 kHz from the main frequency of the quartz resonator with stable generation, stable amplitude and most importantly with very good frequency stability. I had quartz resonators at a frequency of 7033 kHz and, therefore, the range of 7000 - 7033 kHz, that is, almost the entire telegraph section, was easily blocked. The transceiver was based on the "MICRO - 80" transceiver, converted to the 7.0 MHz range, but since its ULF is designed for high-impedance phones, which are not so easy to find now, I decided to make the ULF on the available LM386 IC, as is done in the transceiver "PIXIE", but to increase the sensitivity, turn it on, as in the transceivers "KLOPIK", "STEP". Well, my GPA with frequency shifting on a field-effect transistor with a source follower.

The main goal was to listen to the air and evaluate the stability of the frequency of such a GPA in the simplest transceiver, and also try to make a QSO. I collect everything on the layout. I use KPV-50 as a tuning capacitor (to simplify the design without a vernier device, because the frequency change limit is only 35 kHz, which, in principle, and as shown by further operation, turned out to be quite justified). I check the operation of the GPA, ULF on the instruments, set up the receiving path - everything works. Despite the fact that the mains stabilized power supply is connected, the AC hum is almost inaudible. Now you can listen to the broadcast. I connect the antenna (I have W3DZZ), my favorite telegraph key, brought back from the army, and turn on the power. The noise of the air is literally deafening. I urgently change my headphones for a computer headset with a volume control (by the way, in my opinion, the volume control on the headphones is more convenient than if it were built into this small device). I twist the tuning knob and listen to the broadcast. Simple direct conversion receivers have two-way reception and this is immediately felt. The absence of a telegraph filter affects, the band is wide and therefore several stations are listened to at once. I tune in to the loudest one, listen to it for a while, checking the frequency stability, then insist on another and again check the frequency stability. Everything is fine - the frequency is rooted to the spot. Now you can try and make a QSO. I'm looking for a loud station that gives a general call. And here it is - RA3VMX gives a general challenge. Worried, I call him. I didn’t work on a simple key for a very long time, so the transmission from the habit is not very high quality. I transmit several times at a slow speed de UA3VLO/qrpp and switch to reception without any hope of an answer. And suddenly I hear my call sign. I have been on the air for over 40 years, but the surprise, joy and delight from the fact that they answered me was as much as during the first QSO in my life. Report for me 579-589. I give a response report, thank you for the QSO and we say goodbye. There is the first QSO on the simplest direct conversion transceiver and only with a KT603 transistor at the output! The euphoria passes a little, I calm down, and then it just dawns on me - RA3VMX this is Sasha Semenikhin, a young guy from Vladimir whom I personally know. I write down the date in the hardware log - 05/29/2014 and the time 17.58 UTC of this first QRPP QSO for me. Later, for this first QSO, I sent Sasha a special commemorative QSL.

Happy, I turn the tuning knob again in search of a new station. But the new station turned out to be "People's Chinese Radio", which began AM broadcasting in Russian from 22.00 MSK. The station can be heard with QSB, but at times the signal clogs the entire range, creating such interference that reception is impossible. I hear world news, then a Chinese lesson. But the Chinese letter was somehow not very interesting, and as soon as the station went to QSB, I again try to find an amateur radio station giving a general call. I hear it loud EW1EO , I call and again immediately get a response. Belarus is already much further than Vladimir. Sergey hears me on 599, which was very surprising. But, alas, Sergei was the last correspondent I managed to contact that day. Other stations that I heard loudly and tried to call did not answer me anymore. But even these two connections gave me great satisfaction.

The low power operation got me so excited that I forgot my main FT-840 transceiver and switched completely to QRPP. And, in spite of the fact that each connection was obtained with great difficulty, and in the evenings for 1.5 - 2 hours of long calls it was possible to make 1-2 QSOs, each new correspondent and new area was a real pleasure. To facilitate the work, I replaced a simple key with an electronic one with memory and turned on self-listening on it. When working with this key, the self-listening sound resembles a mosquito squeak. And so the name of the transceiver was born - "KOMARIK".

He shared his new hobby and modest results with R3VL - Mikhail Ladanov, with whom we often communicate, and asked to listen to me on the air, as well as to evaluate the work of my KOMARIK transceiver. He lives nearby and should hear me very well. We call up, turn on and make a QSO. And then it turns out that I call it 700 - 900 Hz higher. And if I get exactly on its frequency, then my reception goes almost to zero beats. It became immediately clear why even very loud stations answered me so badly - I just called them to the side. Having identified this drawback, we check the frequency stability at the edge of the range, where the largest frequency shift of the quartz GPA is. Everything is in order here, the frequency is very good, the tone is clear, quartz. The tests carried out revealed the following important points:

1. The stability of the crystal oscillator is very good even when the frequency drift is over 40KHz.

2. For transmission, it is necessary to shift the frequency down by 800 - 1000 Hz - to a tone that is comfortable for reception.

3. Since the transceiver has two-way reception, in order to get into the desired reception band, you need to tune in to the station above zero beats at the shift frequency.

Now, when it became clear that the reception of the correspondent should be practically in zero beats, I'm trying to make such a QSO. Almost all stations with a volume of 9 began to answer, and even managed to make the farthest QSO for me at that time with YU1DW. But it is very difficult and difficult to receive with a tone of about 50 Hz and below, so I decide to urgently shift the frequency to the transmission. Having tried several options, I settled on the version made in the "PIXIE - 3" transceiver. The frequency shift is electronic. When receiving, a tone familiar to one's hearing is selected in the range of 600 - 1000 Hz, and when the key is pressed, the frequency is shifted down by this amount. And you don't need any relays and switches for transmission. I install this node by hanging mounting. Again I ask Mikhail R3VL to make a QSO. Everything is great. The frequencies match at a comfortable reception for me of about 800 Hz. I was afraid that during manipulation due to switching the GPA there would be a "chirping" signal, but the fears turned out to be in vain. The signal tone is clear and quartz. I'm trying to make a QSO again. And everything went! If earlier in the evening it was difficult to make 1 - 2 QSOs, now 6 - 10 in the same 1.5 - 2 hours. There was only a problem with direct AM detection from a Chinese radio station, but fortunately it appears only after 22.00 MSK and comes with QSB and sometimes even it is almost inaudible, but still there were many cases when communications were broken due to this interference. But despite these difficulties, the geography of my QSOs was rapidly expanding, more and more surprising me with the possibilities of QRPP.

On the advice of Mikhail, R3VL decided to try to work in competitions. The nearest and most convenient competition for me was the "Partisan Radio Operator" competition, in which I took part. The results are impressive. In 3 hours I spent 18 QSOs, which is probably not bad for a "guerrilla power" - 0.3 watts. This summer there were many stations with special callsigns. Almost everyone I heard well answered me. Europe began to respond. I was very pleased with the QSO with F2DX - at that moment it became for me not only a new country, but also the most distant correspondent. And although he received me on 529, the QSO went through without problems and I think that this is due to the good stability of the GPA. And other correspondents, no matter how weak they were, never lost my signal due to frequency instability. I periodically listened and tried to give a general call on the QRP frequency of 7030 kHz, but did not hear anyone. Managed to make only 1 QSO with Sergey UR7VT/QRP and 2 more QSOs, but not on the QRP frequency, but when the operators simply reduced the power to QRP. Curiously, about half of the operators accepted me as UA3VLO/QRP, not UA3VLO/QRPP. Probably, not everyone fit into the head that in our QRO time it is possible to work with a power of less than 1 watt. Each new country, new region, new correspondent brought pleasure and surprise. The simplest transceiver with a KT603 transistor at the output, an ordinary antenna, but they respond well. For three summer months (by the way, this is not very good time for passing on the low bands), on my "Komarik" I made, including competitions, 194 QSOs with 22 countries according to the DXCC diploma list: UA3, EW, YU, OH, SM, UR, YL, LY, HA, SP, RA9, OK, S5, F, ON, DL, OM, LZ, OZ, SV, ES, YO. I made repeated contacts with some correspondents in a week, a month, and almost always repeated contacts were successful. I dreamed of a QSO with the Japanese, whom I often heard well, but all my attempts were unsuccessful. But on the basis of the connections made, I was convinced that on the 7.0 MHz band within a radius of 2000 km, the power of 0.3 watts and my W3DZZ antenna is enough for a stable connection. I was finally convinced of this by participating on August 30-31, 2014 in the "YO-CONTEST" competition. We managed to make 28 QSOs in three hours of the contest. Here is an extract from the report of this contest:

UT TIME	CALL SIGN	QSO NUMBER	UT TIME	CALL SIGN	QSO NUMBER	UT TIME	CALL SIGN	QSO NUMBER
30.08.2014	30.08.2014	31.08.2014

But, the most "star" hour for my "Komarik" was September 2nd. This evening had a good run and, despite intermittent interference from the Chinese AM station, managed to make some interesting QSOs. Time around 18 UTC. At the beginning of the range I hear a soft call OD5OZ . This is Lebanon - DX, but no one answers him. I try to call and immediately get an answer with a confirmation report 599. I am happy about DX and the new country, a few more minutes, strange, but for some reason, despite the long CQ OD5OZ, no one else hears. I continue to listen to the range further and make new interesting QSOs for myself: OV2V - 539, PI4DX - 599 is another new country, TM14JEM - again confirming radio communication report - 599. Suddenly I hear FK8DD/M - New Caledonia giving a general call. He, like Lebanon, passes quietly 579. Since I am used to calling everyone who gives a general call, I call him too. I hear the answer UA3... and at that time the interference of the Chinese radio station again emerges from the QSB AM and completely jams the end of the call sign. I'm just giving a QSO confirmation. It didn't even cross my mind that it could be my callsign. The simplest transceiver with a power of 0.3 watts, a low frequency range of 7.0 MHz, a conventional, omnidirectional W3DZZ antenna, and to be heard in New Caledonia, which is next to Australia, is not even funny. And UA3... we don't have many of them, so I wasn't even upset. AM interference went away only after five minutes. During this time, I had already moved from the frequency to the beginning of the range, where the interference was less, and I managed to make a QSO with M0UNN - report for me 579, England is another new country for me. Three new countries for the evening - it's very good, so I thought. But when a few days later I went to the e-QSL bureau in my mail and saw QSL card FK8DD/M confirming the QSO, I was in a state of shock, not joy.

It can't be, it's probably someone's joke, such a thought came to mind. And only when I found confirmation of this QSO in his log on the FK8DD website, I realized that there was a connection after all. Despite the feeling of joy, it still doesn’t fit in my head, how with such power and in the low-frequency range of 7.0 MHz they heard me in distant Oceania. I know how difficult communication with Oceania is on this band, even with a power of 100 watts, but here the power is less than one watt. I dreamed about a QSO with Japan, but I succeeded with New Caledonia, I didn’t even try to dream of such a connection. So, during that evening I got four new countries, and what a DX!

By e-mail FK8DD I am writing a letter of gratitude about QSO, with the parameters of my transceiver and attaching two photos. Just a few hours later I get a response:

"It"s incredible!!! copy you very nicele here, WX here that day was very nice, no wind and temperatyre 25^C, no QRN in my "Mobile" station. (It's unbelievable!!! I hosted you well the weather that day was good, the temperature was 25C and there was no QRN on my "mobile" station).

These are sometimes the possibilities of QRPP.

One evening, chatting on Skype with his good friend Sergei Savinov RA6XPG from the city of Prokhladny, showed him his "Komarik" and asked him to listen to me on the air. He immediately turned on the transceiver and immediately heard me with a volume of 5 - 6 points, and I myself was able to verify this through Skype. The distance between us is more than 2000 km, which was another confirmation of a stable connection on the 7.0 MHz band with a power of less than 1 watt. The QRPP QSOs I made changed my skepticism about working with such power. It turned out to be a very exciting and interesting activity with unlimited possibilities and, most importantly, interesting QSOs can be made even on the simplest devices, which I did not expect at all.

And now more about the Komarik transceiver itself. Its scheme is shown in Fig1.

A quartz GPA with a frequency shift is assembled on a VT1 transistor. The frequency shift down of quartz resonators connected in parallel is carried out using the inductance L1 and the choke L2. Capacitor C1 for in-range tuning. The GPA signal through the source follower, assembled on the transistor VT2, is fed to the input of the power amplifier, assembled on the transistor VT3 (it is also a mixer of the received signal). The collector circuit VT3 includes the circuit L4, C10, tuned to the middle of the range. From the circuit L4, C10, through the capacitors C13, C14 matching the antenna, the amplified signal enters the antenna. On the transistor VT4, a frequency shift unit is assembled down in the transmission mode. Capacitor C2 selects a frequency shift between reception and transmission within 600 -1000 Hz with a tone familiar to reception. The bass amplifier is assembled on the LM386 IC. To increase the sensitivity, the switching circuit is somewhat different from the typical one. As I have already indicated, such a scheme is used in the Klopik transceiver. Resistor R13 determines the sensitivity of the ULF. As a BA1 phone, it is better to use phones from a computer headset with a volume control. If other phones are used, then in series with them it is necessary to install a variable resistor with a resistance of 200 Ohm, as is done in the Klopik transceiver.

CONSTRUCTION AND DETAILS. The transceiver is assembled on a printed circuit board made of one-sided foil fiberglass. The view of the board from the side of the elements is shown in Figure 2.

The circuit board drawing is shown in Figure 3.

The KPV-50 capacitor is used as a tuning capacitor. Coil L1, with a tuning core, is wound on a frame with a diameter of 12 mm with PEV-2 wire 0.2 turn to turn. The number of turns is 60-80. Its inductance is about 30 mcg. L2 is a high frequency inductor and the largest size is selected to obtain the best GPA stability. Quartz resonators are the same, for a frequency of 7030 - 7050 kHz. In the last design, I used resonators at a frequency of 7050 kHz. At the lower end of the range, the frequency remained the same stable, but it became more difficult to tune into the station, and 50 kHz overlap for the telegraph section on this range is useless. Therefore, if you do not use a vernier device, it is advisable to put an additional capacitor with a capacitance of 20 - 24 pF in parallel with capacitor C1 in order to reduce the upper frequency to 7035 - 7040 kHz. Choke L3 - any standard 100 micrograms. The L4 coil is wound turn to turn on a frame with a diameter of 8 mm (from the inverter of old TVs) and contains 24 turns of PEV-2 0.35 wire with a tap from 6 turns on top. The capacitor 5-50 PF is a small-sized trimmer, I have a TZ03. View of the assembled device is shown in PHOTO 4

FORMING. With serviceable parts and no errors in installation, as a rule, everything works right away. ULF is checked by a characteristic growl when a hand is brought to the input (terminal 3 of the IC) By reducing the value of the resistor R13, they achieve maximum gain, but without bringing the ULF to excitation. GPA, as a rule, also works immediately. By connecting an oscilloscope or an RF voltmeter to the output of the source follower (in parallel with resistor R6), the operation of the GPA is checked. If there is no signal, each resonator is checked in turn by shorting its lower output to the case. If everything works, the L2 choke is connected to the resonator, and its lower output is shorted to ground. Generation should not fail. Next, the L1 coil is connected, and the presence of generation is again checked. And, lastly, a variable capacitor C1 is connected. If the GPA is operating normally, a frequency meter is connected to the output of the source follower (in parallel with resistor R6) to set the range limits. Rotating the core of the coil L1, set the lower frequency of the GPA with a margin of 1-2 kHz, i.e. 6998 kHz. Set the capacitor C1 to the minimum position. The GPA frequency can be 1-2 kHz higher than the frequency of quartz resonators. To tune the output stage, instead of the antenna, its equivalent is connected - a load resistor with a resistance of 50-75 Ohms and an RF voltmeter parallel to it. Set the frequency of the GPA in the middle of the range. Close contacts KEY. By rotating the core of the L4 coil, the circuit is tuned to resonance and the optimal connection with the antenna tuning capacitor C14 is selected according to the maximum voltage on the antenna equivalent. And finally, the frequency shift node is infused. In receive mode, the voltage at the VT4 collector should be zero. When you press the key, the voltage at the VT4 collector should be close to the supply voltage. By connecting the frequency meter in parallel with the resistor R6 at the output of the source follower, measure the frequency and close the key (the equivalent load must be connected). By changing the capacitance of the capacitor C2 within 3.9-5.6 pF, a frequency shift down by 800-1000 Hz is selected, corresponding to a comfortable tone for reception. The antenna is connected and, if necessary, the connection with the antenna capacitor C14 is adjusted according to the maximum volume of remote radio stations.

This transceiver is the simplest and has only 0.3 watts of power, and there are many more disadvantages. For example, there is no telegraph filter, no self-monitoring node, two-way reception, direct AM detection of powerful broadcast stations, but the pleasure that you get when making interesting QSOs on such a device covers all the shortcomings.

And in conclusion, I would like to thank RA3VX Silchenko Vyacheslav for help with the design of the QSL card.

Yuri Lebedinsky UA3VLO Alexandrov 2015

With the spread of the Internet, amateur radio, no matter how sorry, gradually began to fade away. Where did the army of radio hooligans go, the legions of "fox hunters" with direction finders and their other colleagues ... They disappeared, crumbs remained. There is no mass agitation at the state level, and in general, the system of values ​​has changed - young people more often prefer to choose other entertainment for themselves. Of course, Morse code is not often used in the current digital age, and radio communication in its original form is increasingly losing its position. However, amateur radio as a hobby is a mixture of a kind of romance of wandering with a fair amount of skills and knowledge. And the opportunity to creak with your brains, and put your hands on it, and rejoice at your soul.

And yet I did not shame my brothers,
but embodied their forces of union:
I, like a sailor, furrowed the elements
and, as a player, prayed for luck.

M. K. Shcherbakov "Song of the Page"

However, to the point. So.

When choosing a design for repetition, there were several requirements arising from my initial knowledge in the field of designing RF equipment - the maximum detailed description, especially in terms of tuning, no need for special RF measuring instruments, available element base. The choice fell on Viktor Timofeevich Polyakov's direct conversion transceiver.

transceiver - communication equipment, radio station. The receiver and transmitter are in one bottle, and they have a part of the cascades in common.

Entry-level SSB transceiver, single band, 160m, direct conversion, tube output stage, 5W. There is a built-in matching device for working with antennas of various wave impedances.

SSB - single-sideband modulation (Amplitude modulation with one sideband, from the English Single-sideband modulation, SSB) - a type of amplitude modulation (AM), widely used in transceiver equipment for efficient use of the channel spectrum and the power of the transmitting radio equipment.

The principle of direct conversion to obtain a single-sideband signal allows, among other things, to do without specific radio elements inherent in a superheterodyne circuit - electromechanical or quartz filters. The range of 160m, for which the transceiver is designed, is easy to change to a range of 80m or 40m by reconfiguring the oscillatory circuits. The output stage on a radio tube does not contain expensive and rare RF transistors, is not picky about the load and is not prone to self-excitation.

Let's take a look at the schematic diagram of the device.

A detailed analysis of the circuit can be found in the author's book, there is also an author's printed circuit board, transceiver layout and case sketch.
Compared to the author's design, the following changes were made to its execution. First of all - layout.

The transceiver version, designed to operate on the lowest frequency amateur band, fully allows for a “low-frequency” layout. In their own design, solutions were used that are more applicable to RF equipment, in particular, each logically complete node was located in a separate shielded module. Among other things, this makes it much easier to improve the device. Well, I was inspired by the possibility of a simple retuning to 80, or even 40m bands. There, such an arrangement would be more appropriate.

Toggle switch "Reception-transmission", replaced by several relays. Partly because of the desire to control these modes from the remote button on the sole of the microphone, partly due to the more correct wiring of the signal circuits - now they did not need to be dragged from afar to the toggle switch on the front panel (each relay was located at the switching point).

The design of the transceiver introduced a vernier with a large deceleration and, this makes it much more convenient to tune in to the desired station.

What was used.

Tools.
Soldering iron with accessories, a tool for radio installation and small metalwork. Metal scissors. A simple carpentry tool. Used a milling machine. Blind rivets with special tongs for their installation came in handy. Something for drilling, including holes on a printed circuit board (~ 0.8 mm), can be contrived with one screwdriver - the scarves are specific, there are few holes. Engraver with accessories, hot glue gun. It is good if you have a computer with a printer at hand.

Materials.
In addition to radio elements - a mounting wire, galvanized steel, a piece of organic glass, foil material and chemicals for the manufacture of printed circuit boards, related trifles. Not thick plywood for the body, small carnations, wood glue, a lot of sandpaper, paint, varnish. A bit of mounting foam, thin dense foam - "Penoplex" 20 mm thick - for thermal insulation of some cascades.

First of all, in AutoCAD, the layout of both the entire apparatus and each module was drawn.

The modules themselves were made - printed circuit boards, "mushrooms" of the module cases made of galvanized steel. Boards are assembled, loop coils are wound and installed, boards are soldered into individual screen covers.

A variable capacitor for a local oscillator - with every second plate removed. I had to disassemble and solder the stator blocks, then put everything back in place.

The body is made of 8 mm plywood, after adjusting the openings and holes, the box is sanded and covered with two layers of gray paint. From the inside, the box is finished with the same galvanized steel, and the final installation of elements and modules has begun.

The galette switch and the variable capacitor of the matching device are located near the antenna connector, this allows you to shorten the connecting wires as much as possible. To control them from the front panel, extensions of their shafts from a 6mm threaded stud and connecting nuts with stoppers are used.

The axis of the tuning vernier is made from a shaft from a broken inkjet printer, on the same axis there was a braking unit, which also came in handy. The groove holding the vernier cable was made using an engraver.

The special pulley, the cable itself and the spring providing tension are taken from a tube radio.

The tuning knob is made from two large gears from the same printer. The space between them is filled with hot glue.

The walls of the local oscillator module are finished with a layer of mounting foam, this allows you to reduce the "frequency drift" due to heating when tuning to the station.

The module of the telephone and microphone amplifier is placed on the rear wall of the case, for its (module) protection against mechanical damage, releases are made on the side walls of the case.

Setting the local oscillator of the transceiver. For her, a simple RF prefix was ​​made for a multimeter, which allows you to evaluate the level of RF voltage, for example.

Initially, it was decided to change the circuit of the output stage of the transmitter to a semiconductor one, powered by the same 12 V. In the photo above, it is he who is not fully assembled - a milliammeter for a higher current, an additional winding on the P-loop coil, only low-voltage power.

Scheme of changes. The output power is about 0.5W.

In the future, it was decided to return to the original. I had to replace the milliammeter with a more sensitive one, add the missing elements, change the power supply.

The power amplifier module is thermally insulated from other structural elements, as it is a source of a large amount of heat. Its natural ventilation is organized - a field of holes is made in the basement of the case and on the cover above the module.

The basement of the building also contains a number of blocks and modules.

The transceiver circuit has the simplest solutions for individual nodes and does not shine with characteristics, however, there are a number of improvements and improvements aimed at both improving the performance characteristics and improving ease of use. This is the introduction of signal sideband switching, automatic gain control, the introduction of CW mode during transmission. The suppression of the non-working sideband can also be slightly increased by reducing the spread in the characteristics of the mixer diodes, for example, by using a KDS 523V diode assembly instead of the V14 ... V17 diodes. Improvement of individual nodes can be performed according to the schemes from. It is also worth paying attention to solutions. The applied arrangement allows to do it quite conveniently.

Literature.
1. V.T.POLYAKOV. DIRECT CONVERSION TRANSCEIVERS Publishing House DOSAAF USSR. 1984
2. Scheme of the attachment to the multimeter for measuring RF.
3. Dylda Sergey Grigorievich. TRX's small-signal direct conversion SSB path on the 80m band