Homemade VHF FM receivers. A simple direct amplification VHF receiver. Diagram and description. Assembly, adjustment, operating procedure
For those who like to tinker, I offer a diagram and design of a homemade compact receiver operating on two VHF bands. The first one covers the carrier frequencies of audio signals from TV channels I-III (66-74 MHz). The second range extends from 85 to 108 MHz, including carrier frequencies of audio signals of TV channels IV and V. Receiver sensitivity is 5 µV, the nominal output power into an 8 Ohm load is only 0.11 W. Power is supplied from any DC source with a voltage of 6-14 V.
Among the operational advantages of the design in question is the economical consumption of electricity. This is supported by such an important parameter as the current consumed by the equipment in silent mode. After all, it is only 12-15 mA here (at Upit = 6V)!
High sensitivity and other equally good indicators are largely due to the fact that this receiver is based on the K174XA34 integrated circuit (see Modelist-Constructor magazine No. 3, 1993). It contains an aperiodic UHF, local oscillator, mixer, amplifier with amplifier-limiter, built-in active filters, bass reflex, FM demodulator, noise reduction system and preliminary ULF. Since the intermediate frequency used is about 70 kHz, it is not possible to do without a deviation compression system of about 10 times.
The low-frequency amplifier, made on the K157UD1 analog microcircuit, also makes its worthy contribution to providing the VHF receiver with good characteristics. This MS, as they say, does not need advertising. The output load is an 8-ohm dynamic head. In addition to 0.5GDSh1-8 indicated on the principle electrical diagram, 0.5GDSh2 and other analogues are quite suitable (including loudspeakers with a coil resistance of more than 8 Ohms from old, out-of-date radio equipment).
From the rest technical solutions, used in the design of the receiver under consideration, one cannot fail to note the stable current generator. Made on transistors VT1, VT2, it provides the required 0.5 mA flowing through VT3 and a chain of load resistors R4-R6. In addition, the circuit is designed in such a way that it allows the replacement of some parts with others, similar ones. In particular, instead of KT315G transistors, KT342, KT3102 and other semiconductor triodes with similar parameters can be used.
The variable resistors are the same: SP-0.4; local oscillator capacitor C3 - with standardized TKE. Coil L1 contains 8, and L2 - 5 turns PEV2-0.45 (PEV2-0.5), wound on a mandrel with a diameter of 3.5 mm; L3 has 20 turns of the same wire, but is made on a mandrel with a diameter of 2 mm.
The circuit, assembled on a printed circuit board accurately and from serviceable parts, begins to work immediately when power is supplied. You just need to make sure that the total current consumed in silent mode is 12-15 mA.
It will also not be superfluous to “fit” both ranges within the required frequency limits. This is done using a calibrated device - a standard signal generator - or an auxiliary VHF receiver located nearby. Rough adjustment (at the extreme positions of the variable resistor R5 slider) is carried out by selecting the value of R4, and adjustment is carried out by stretching or compressing the turns of coils L1 and L2.
The finished receiver is placed in a plastic case, external dimensions which is 85x60x30 mm. The printed circuit board with the mounted circuit is secured using additional nuts: M8 on the head of the microtoggle switch and M6 on the threaded necks of the variable resistors. With the power supply, speaker, antenna and grounding located outside, the VHF receiver is docked using a 6-pin electrical radio connector, the socket part of which is located inside the case itself.
For reliable reception of radio stations, a standard telescopic antenna or a piece of flexible wire experimentally tested in length (usually 400-600 mm) and direction is used. When the sound of radio broadcasts is excessively strong, sometimes they replace the volume control, increasing its value. If the signal from the low-frequency amplifier is small, then preference is given to a variable resistor 1310 with lower resistance.
V. ZLOBIN, Yoshkar-Ola
Noticed a mistake? Select it and click Ctrl+Enter to let us know.
Every novice radio amateur wants to assemble a device that is not only interesting to assemble and works, but also useful. Today I will tell you how to make an inexpensive FM receiver on a chip TA8164P according to a simplified scheme. Microcircuit TA8164P can be replaced with a cheaper one TA2003 (CD2003), but the reception quality will drop significantly. The following is the receiver diagram:
As you have already noticed, there is no variable capacitor in the circuit; it is replaced by a pair of varicaps and a variable resistance. In this receiver, the resistance needs to be a variable multi-turn, but in my case there is a tuning multi-turn resistor. The following types can be used:
Varicap KV109 can be used with any letter designation, I used KV109A (with white dot). Varicap pinout (the leg on the marking side is the anode, and the leg on the side of the convex mark is the cathode):
If you look closely at the diagram, the elements marked 10.7 MHz differ from each other in the number of pins. An element with two terminals can be called a quartz resonator, but it is more correctly called a descriminator filter. An element with three terminals is a radio frequency filter. These elements are recommended to be used by companies Murata.
Coil L1 is wound in the amount of 11 turns, with a 0.5 mm wire, on a hollow frame (a drill can be used for winding) with a diameter of 2.5 mm. L2 – 10 turns, 0.5 mm wire, on the same frame. This receiver has a very low output power, which is only enough for a high-impedance (40-60 Ohm) earphone, so you need to use ULF.
The printed circuit board for this device is very simple; it can be drawn with a marker. The figure shows the device's printed circuit board, which can be
Greetings! In this review I want to talk about a miniature receiver module operating in the VHF (FM) range at a frequency from 64 to 108 MHz. I came across a picture of this module on one of the specialized Internet resources, and I became curious to study it and test it.
I have a special awe for radios; I have loved collecting them since school. There were diagrams from the magazine “Radio”, and there were just construction kits. Every time I wanted to assemble a better receiver and smaller in size. The last thing I assembled was a design on the K174XA34 microcircuit. Then it seemed very “cool”, when in the mid-90s I first saw a working circuit in a radio store, I was impressed)) However, progress is moving forward, and today you can buy the hero of our review for “three kopecks”. Let's take a closer look at it.
View from above. 
View from below. 
For scale next to the coin. 
The module itself is built on the AR1310 chip. I couldn’t find an exact datasheet for it, apparently it was made in China and its exact functional structure is not known. On the Internet you can only find wiring diagrams. A Google search reveals: "This is a highly integrated, single-chip, stereo FM radio receiver. The AR1310 supports the FM frequency range of 64-108 MHz, the chip includes all FM radio functions: low noise amplifier, mixer, oscillator and low-dropout stabilizer. Requires a minimum of external components. Has good quality audio signal and excellent reception quality. AR1310 does not require control microcontrollers and no additional software, except 5 buttons. Operating voltage 2.2 V to 3.6 V. consumption 15 mA, in sleep mode 16 uA ".
Description and specifications AR1310
- Reception of FM frequencies range 64 -108 MHz
- Low power consumption 15 mA, in sleep mode 16 uA
- Supports four tuning ranges
- Using an inexpensive 32.768KHz quartz resonator.
- Built-in two-way auto search function
- Support electronic volume control
- Supports stereo or mono mode (when contacts 4 and 5 are closed, stereo mode is disabled)
- Built-in 32 Ohm Class AB headphone amplifier
- Does not require control microcontrollers
- Operating voltage 2.2V to 3.6V
- In SOP16 housing
Pinout and dimensions module. 
AR1310 microcircuit pinout. 
Connection diagram taken from the Internet. 
So I made a diagram for connecting the module. 
As you can see, the principle couldn’t be simpler. You will need: 5 tact buttons, a headphone jack and two 100K resistors. Capacitor C1 can be set to 100 nF, or 10 μF, or not at all. Capacitances C2 and C3 from 10 to 470 µF. As an antenna - a piece of wire (I took a MGTF 10 cm long, since the transmitting tower is in my neighboring yard). Ideally, you can calculate the length of the wire, for example at 100 MHz, by taking a quarter wave or one eighth. For one eighth it will be 37 cm.
I would like to make a remark regarding the diagram. AR1310 can operate in different bands (apparently for faster station search). This is selected by a combination of pins 14 and 15 of the microcircuit, connecting them to ground or power. In our case, both legs sit on VCC.
Let's start assembling. The first thing I encountered was the non-standard pin-to-pin pitch of the module. It is 2 mm, and it will not be possible to fit it into a standard breadboard. But it doesn’t matter, I took pieces of wire and just soldered them in the form of legs. 
Looks good)) Instead of a breadboard, I decided to use a piece of PCB, assembling a regular “fly board”. In the end, this is the board we got. The dimensions can be significantly reduced by using the same LUT and smaller components. But I didn’t find any other parts, especially since this is a test bench for running. 
After applying power, press the power button. The radio receiver worked immediately, without any debugging. I liked the fact that the search for stations works almost instantly (especially if there are many of them in the range). The transition from one station to another takes about 1 s. The volume level is very high, it is unpleasant to listen to at maximum. After turning off the button (sleep mode), it remembers the last station (if you do not completely turn off the power).
Sound quality testing (by ear) was carried out using Creative (32 Ohm) drop-type headphones and Philips vacuum-type headphones (17.5 Ohm). I liked the sound quality in both. No squeakiness, just enough low frequencies. I'm not much of an audiophile, but I was pleasantly pleased with the sound of the amplifier of this microcircuit. I couldn’t turn up the maximum volume in the Philips, the sound pressure level was painful.
I also measured the current consumption in sleep mode 16 μA and in working mode 16.9 mA (without connecting headphones). 
When connecting a load of 32 Ohms, the current was 65.2 mA, and with a load of 17.5 Ohms - 97.3 mA. 
In conclusion, I will say that this radio receiver module is quite suitable for domestic use. Even a schoolchild can assemble a ready-made radio. Among the “cons” (more likely not even cons, but features) I would like to note the non-standard pin spacing of the board and the lack of a display to display information.
I measured the current consumption (at a voltage of 3.3 V), as we see, the result is obvious. With a load of 32 Ohms - 17.6 mA, with 17.5 Ohms - 18.6 mA. This is a completely different matter!!! The current varied slightly depending on the volume level (within 2 - 3 mA). I corrected the diagram in the review. 
This circuit runs on just one 1.5 V battery. An ordinary earphone with a total impedance of 64 Ohms is used as an audio playback device. The battery power passes through the headphone jack, so you just need to pull the headphones out of the jack to turn off the receiver. The sensitivity of the receiver is sufficient that several high-quality HF and DV stations can be used on a 2-meter wire antenna.
Coil L1 is made on a ferrite core 100 mm long. The winding consists of 220 turns of PELSHO 0.15-0.2 wire. Winding is carried out in bulk on a paper sleeve 40 mm long. The tap must be made from 50 turns from the grounded end.
Receiver circuit with just one field-effect transistor
This version of the circuit of a simple single-transistor FM receiver works on the principle of a super-regenerator.
The input coil consists of seven turns of copper wire with a cross-section of 0.2 mm, wound on a 5 mm mandrel with a tap from the 2nd, and the second inductance contains 30 turns of 0.2 mm wire. The antenna is a standard telescopic one, powered by one Krona type battery, the current consumption is only 5 mA, so it will last for a long time. Tuning to a radio station is carried out by a variable capacitor. The sound at the output of the circuit is weak, so almost any homemade ULF will be suitable to amplify the signal.
The main advantage of this scheme in comparison with other types of receivers is the absence of any generators and therefore there is no high-frequency radiation in the receiving antenna.
The radio wave signal is received by the receiver antenna and is isolated by a resonant circuit on inductance L1 and capacitance C2 and then goes to the detector diode and is amplified.
FM receiver circuit using a transistor and LM386. |
I present to your attention a selection simple circuits FM receivers for the range 87.5 to 108 MHz. These circuits are quite simple to repeat, even for beginner radio amateurs, they are not large in size and can easily fit in your pocket.
Despite their simplicity, the circuits have high selectivity and a good signal-to-noise ratio and are quite enough for comfortable listening to radio stations
The basis of all these amateur radio circuits radio receivers are specialized microcircuits such as: TDA7000, TDA7001, 174XA42 and others.
The receiver is designed to receive telegraph and telephone signals from amateur radio stations operating in the 40-meter range. The path is built according to a superheterodyne circuit with one frequency conversion. The receiver circuit is designed in such a way that a widely available element base is used, mainly transistors of the KT3102 type and 1N4148 diodes.
The input signal from the antenna system is fed to the input bandpass filter on two circuits T2-C13-C14 and TZ-C17-C15. The connection between the circuits is capacitor C16. This filter selects the signal within the range of 7 ... 7.1 MHz. If you want to work in a different range, you can adjust the circuit accordingly by replacing transformer coils and capacitors.
From the secondary winding of the HF transformer TZ, the primary winding of which is the second filter element, the signal goes to the amplifier stage on transistor VT4. The frequency converter is made using diodes VD4-VD7 in a ring circuit. The input signal is supplied to the primary winding of transformer T4, and the smooth range generator signal is supplied to the primary winding of transformer T6. The smooth range generator (VFO) is made using transistors VT1-VT3. The generator itself is assembled on transistor VT1. The generation frequency lies in the range of 2.085-2.185 MHz, this range is set by a loop system consisting of inductance L1, and a branched capacitive component of C8, C7, C6, C5, SZ, VD3.
Adjustment within the above limits is carried out by variable resistor R2, which is the tuning element. It regulates constant pressure on the VD3 varicap, which is part of the circuit. The tuning voltage is stabilized using a zener diode VD1 and a diode VD2. During the installation process, overlap in the above frequency range is established by adjusting the capacitors SZ and Sb. If you want to work in a different range or with a different intermediate frequency, a corresponding restructuring of the GPA circuit is required. It’s not difficult to do this armed with a digital frequency meter.
The circuit is connected between the base and emitter (common minus) of transistor VT1. The PIC required to excite the generator is taken from a capacitive transformer between the base and emitter of the transistor, consisting of capacitors C9 and SY. RF is released at the emitter VT1 and goes to the amplifier-buffer stage on transistors VT2 and VT3.
The load is on the RF transformer T1. From its secondary winding, the GPA signal is supplied to the frequency converter. The intermediate frequency path is made using transistors VT5-VT7. The output impedance of the converter is low, so the first stage of the amplifier is made on transistor VT5 according to the circuit with common base. From its collector, the amplified IF voltage is supplied to a three-section quartz filter at a frequency of 4.915 MHz. If there are no resonators for this frequency, you can use others, for example, at 4.43 MHz (from video equipment), but this will require changing the settings of the VFO and the quartz filter itself. The quartz filter here is unusual; it differs in that its bandwidth can be adjusted.
Receiver circuit. The adjustment is carried out by changing the containers connected between the filter sections and the common minus. For this, varicaps VD8 and VD9 are used. Their capacitances are regulated using a variable resistor R19, which changes the reverse DC voltage across them. The filter output is to the T7 RF transformer, and from it to the second stage of the amplifier, also with a common base. The demodulator is made on T9 and diodes VD10 and VD11. The reference frequency signal comes to it from the generator at VT8. It should have a quartz resonator the same as in a quartz filter. The low-frequency amplifier is made using VT9-VT11 transistors. The circuit is two-stage with a push-pull output stage. Resistor R33 regulates the volume.
The load can be both the speaker and headphones. Coils and transformers are wound on ferrite rings. For T1-T7, rings with an outer diameter of 10 mm are used (imported type T37 is possible). T1 - 1-2=16 vit., 3-4=8 vit., T2 - 1-2=3 vit., 3-4=30 vit., TZ - 1-2=30 vit., 3-4= 7 vit., T7 -1-2=15 vit., 3-4=3 vit. T4, TB, T9 - 10 turns of wire folded in three, solder the ends according to the numbers on the diagram. T5, T8 - 10 turns of wire folded in half, solder the ends according to the numbers on the diagram. L1, L2 - on rings with a diameter of 13 mm (imported type T50 is possible), - 44 turns. For all, you can use PEV wire 0.15-0.25 L3 and L4 - ready-made chokes 39 and 4.7 μH, respectively. KT3102E transistors can be replaced with other KT3102 or KT315. Transistor KT3107 - on KT361, but it is necessary that VT10 and VT11 have the same letter indices. 1N4148 diodes can be replaced with KD503. The installation was carried out in a three-dimensional manner on a piece of foil fiberglass laminate measuring 220x90 mm.
This article provides a description of three simplest receivers with a fixed tuning to one of the local stations in the MF or LW range; these are extremely simplified receivers powered by a Krona battery, located in housings subscriber loudspeakers containing a speaker and a transformer.
The schematic diagram of the receiver is shown in Figure 1A. Its input circuit is formed by coil L1, capacitor cl and an antenna connected to them. The circuit is tuned to a station by changing capacitance C1 or inductance Ll. The RF signal voltage from part of the coil turns is supplied to the diode VD1, which works as a detector. From variable resistor 81, which is the load of the detector and the volume control, low frequency voltage is supplied to the base VT1 for amplification. The negative bias voltage at the base of this transistor is created by the constant component of the detected signal. Transistor VT2 of the second stage of the low-frequency amplifier has a direct connection with the first stage.
The low-frequency oscillations amplified by it pass through the output transformer T1 to loudspeaker B1 and are converted into acoustic oscillations. The receiver circuit of the second option is shown in the figure. The receiver assembled according to this circuit differs from the first option only in that its low-frequency amplifier uses transistors different types conductivity. Figure 1B shows a diagram of the third version of the receiver. Its distinctive feature is positive feedback carried out using the L2 coil, which significantly increases the sensitivity and selectivity of the receiver.
To power any receiver, a battery with a voltage of -9V is used, for example, “Krona” or made up of two 3336JI or individual elements, it is important that there is enough space in the subscriber loudspeaker housing in which the receiver is assembled. While there is no signal at the input, both transistors are almost closed and the current consumption of the receiver in rest mode does not exceed 0.2 Ma. The maximum current at the highest volume is 8-12 Ma. The antenna is any wire about five meters long, and the grounding is a pin driven into the ground. When choosing a receiver circuit, you need to take into account local conditions.
At a distance of about 100 km to the radio station, using the above antenna and grounding, loud-speaking reception by receivers is possible according to the first two options, up to 200 km - the scheme of the third option. If the distance to the station is no more than 30 km, you can get by with an antenna in the form of a wire 2 meters long and without grounding. The receivers are mounted by volumetric installation in the housings of subscriber loudspeakers. Remaking the loudspeaker comes down to installing a new volume control resistor combined with the power switch and installing sockets for the antenna and grounding, while the isolation transformer is used as T1.
Receiver circuit. The input circuit coil is wound on a piece of ferite rod with a diameter of 6 mm and a length of 80 mm. The coil is wound on a cardboard frame so that it can move along the rod with some friction. To receive DV radio stations, the coil must contain 350, with a tap from the middle, turns of PEV-2-0.12 wire. To operate in the CB range there must be 120 turns with a tap from the middle of the same wire, a coil feedback for the receiver of the third option, they are wound on a contour coil; it contains 8-15 turns. Transistors must be selected with a gain Vst of at least 50.
Transistors can be any germanium low-frequency of the appropriate structure. The transistor of the first stage must have the minimum possible reverse collector current. The role of a detector can be performed by any diode of the D18, D20, GD507 and other high-frequency series. The variable volume control resistor can be of any type, with a switch, with a resistance from 50 to 200 kilo-ohms. It is also possible to use a standard resistor of the subscriber loudspeaker; usually resistors with a resistance of 68 to 100 kohms are used. In this case, you will have to provide a separate power switch. A trimmer ceramic capacitor KPK-2 was used as a loop capacitor.
Receiver circuit. It is possible to use a variable capacitor with a solid or air dielectric. In this case, you can insert a tuning knob into the receiver, and if the capacitor has a sufficiently large overlap (in a two-section, you can connect two sections in parallel, the maximum capacity will double) you can receive stations in the LW and SW range with one medium-wave coil. Before tuning, you need to measure the current consumption from the power source with the antenna disconnected, and if it is more than one milliampere, replace the first transistor with a transistor with a lower reverse collector current. Then you need to connect the antenna and by rotating the rotor of the loop capacitor and moving the coil along the rod, tune the receiver to one of the powerful stations.
Converter for receiving signals in the 50 MHz range The IF-LF transceiver path is intended for use in the latter, superheterodyne circuit, with single frequency conversion. Intermediate frequency selected equal to 4.43 MHz (quartz from video equipment is used)
Magnetic ferrite antennas are good for their small size and well-defined directivity. The antenna rod should be positioned horizontally and perpendicular to the direction of the radio. In other words, the antenna does not receive signals from the ends of the rod. In addition, they are insensitive to electrical interference, which is especially valuable in large cities, where the level of such interference is high.
The main elements of a magnetic antenna, designated in the diagrams by the letters MA or WA, are an inductor coil wound on a frame made of insulating material, and a core made of high-frequency ferromagnetic material (ferrite) with high magnetic permeability.
Receiver circuit. Non-standard detector |
Its circuit differs from the classical one, first of all, in a detector built on two diodes and a coupling capacitor, which allows you to select the optimal circuit load for the detector, and thereby obtain maximum sensitivity. With a further decrease in capacitance C3, the resonance curve of the circuit becomes even sharper, i.e., the selectivity increases, but the sensitivity decreases somewhat. The oscillating circuit itself consists of a coil and a variable capacitor. The inductance of the coil can also be varied within wide limits by moving the ferrite rod in and out.
IN Soviet times The products of the Riga radio plant were very popular, in particular, the receivers “Spidola”, “VEF-Spidola”, “VEF-12”, “VEF-201”, “VEF-202”. The devices were expensive and considered prestigious, they were taken care of, and therefore some copies of this equipment have survived to this day. The VEF receiver receives short waves well, and in the pre-perestroika era, radio amateurs modified them by increasing the HF subbands (introducing “forbidden” 16 meters, 13 meters, etc.).
Now the full operation of the receiver is hampered by the lack of VHF bands. This is especially acute in regions where there is only one station left in the NE and Far East (and they are duplicated on VHF).
The number of VHF bands you can enter depends on how many existing bands you can sacrifice.
It turned out to be very simple to enter two or one VHF range into a VEF type receiver if you use KXA058 microassemblies (one for each new range). But first you need to select one or two unnecessary bands from the list of receiver bands. This could be NE and LW, some HF sub-bands (for example, 75 meters).
After unnecessary ranges have been identified, you need to remove the plastic strips of these ranges from the switch and completely dismantle them (leaving only a pair of adjusted capacitors). Then, on each of these strips, mount the circuit shown in the figure in a three-dimensional manner. The microassembly can be glued to the plank with Moment glue or other quick-drying glue.
All new parts are designated by hundredths. The remaining details are according to the receiver diagram. Contacts 1, 8, 11 and 15 of the strip, in fact. used for their intended purpose: “1” - to the antenna, “8” - to the variable capacitor, “5” - common plus of the receiver power supply, “11” - minus of the local oscillator power supply (6V).
On the switches of different receivers there are free contacts No. 2, 3 or 9. In this case, the receiver is “VEF-12”. and contact 3 is free in it. Through this contact, output voltage 34 is supplied to the input of the ultrasonic receiver (connection point R29 and C71).
Coil L1 is wound on one of the coil frames provided on the bar. The ferrite core is removed from the frame and the existing windings are completely wound. Coil L1 for the range of 84-75 MHz should contain 12-15 turns of PEV 0.23 wire, for the range of 88-108 MHz - 7-9 turns of the same wire.
The tuning consists of setting the ranges using trimming capacitors C103 and C104, the role of which is performed by trimmed capacitors located on the strips. In some VEF receivers there are no tuning capacitors on the HF strips; permanent capacitors are installed in their place. In this case, tuning capacitors must be installed additionally (KPK, 6..25pF).
When installing the circuit in “VEF”, you need to remember that its circuit is assembled on MP41 and P403 transistors, P-N-P structures, and therefore, the common wire is at a positive potential, and the power bus is negative.
In a similar way, you can upgrade any old receiver without VHF bands, but the VEF is more convenient. that there is no need to introduce additional switches - all switching is performed by the old drum.
The VHF-FM strip can, in principle, be assembled on the K174XA34 or K174XA42 microcircuit, but this will require either a much denser mounted installation or the manufacture of a small-sized printed circuit board Exactly sized for installation on the drum bar.
The arrangement in the drum will be more dense due to more new elements and therefore not very convenient. The option for K174XA34 or K174XA42, in this case, can be considered acceptable, but there is no opportunity to purchase KXA058.