Having looked through many topics, I saw ways to assemble different receivers, including detector ones.
But what if after a BP or in another extreme situation you need to send a signal, for example, for help, or others. But that's not the point. This method was tested by me, since I collected and everything works.
Making a simple walkie-talkie with your own hands is much more difficult than buying a ready-made version in a store, but still.
Here are all the materials you need to assemble a homemade walkie-talkie with a signal radius of about 1.5 km:
3 transistors P416B, 4 transistors MP42
Resistors for 3K, 160K and 4.7K for 2 pieces, for 22K, 36K, 100K, 120K and 270K for 1 piece and as many as 6 resistors of type 6.8K
Capacitors type 10МК * 10V, 3300, 1000, 100, 6, 5-20 2 pieces, 22, 10 and 0.047МК 1 each and as many as 4 capacitors of type 5МК * 10V
and
Antenna, microphone, speaker, on / off switch, DC source, 2 PCB boards, connecting wires and wire with a diameter of 0.5 and 0.1 mm;
multiplied by the number of homemade radios that you are going to make with your own hands.
Scheme of a simple homemade radio:
Where, A1 is one common antenna for sending and receiving a signal, SA1 is the power switch, and the SA2 switch will connect the homemade radio station to a current source: while sending a signal to the transmitter, and, accordingly, to the receiver during receiving. 
The following figure clearly shows the winding diagram of the coils, the basis for which will be plexiglass, polystyrene or, in extreme cases, cardboard cylinders with a diameter of 0.8 cm and a height of 2 cm, and as a winding - 1 layer of copper wire with a diameter of 0.5 mm, which is called a turn to a turn ... The coils L5 and L1 of your simple homemade radio with your own hands should have ten turns, the L2 coil should consist of four turns and is located between the halves of the L3 winding, which consists of eight turns and has a wire outlet in the middle. For those who do not get into simple circuits of a walkie-talkie with their own hands, the coils L3 and L2 are wound on the same base.
L4 and L6 represent a 200-turn winding of 0.1 millimeter wire around the body of MLT-0.5 resistors with a minimum resistance of 1 MΩ. 
If you have read to these lines, then you probably understand at least something in electrical engineering, and therefore place the parts on textolite boards (one of them will be with a master oscillator, and the other with a low-frequency amplifier and a receiver) on one side and connecting them on to the other side with a wire with insulation of 0.2-0.3 mm in diameter, it should not be difficult for you, however, as well as connecting the batteries with a stranded wire insulated with PVC. You can make printed wiring if you have a foil-clad getinax, and the frame of your simple home-made walkie-talkie - with centimeter-long pieces of copper wire driven into holes with a diameter of one millimeter. 
It remains to make sure that the windings of the chokes and coils are mutually perpendicular, the handle of the capacitor C15 is located on the front panel of the radio station, and the master oscillator is separated from other parts of your simple homemade radio with your own hands by a tin screen, which in turn is connected to the "+" power supply.
The absence of a microphone will successfully correct the presence of a pair of high-impedance headphones, and instead of a telescopic antenna from the radio receiver, you can use a meter brass tube with a diameter of 0.5 cm.
Setting up and debugging a homemade radio
Even if you regularly attended all the classes of the circle of young radio amateurs, it is not a fact that your simple walkie-talkie with your own hands will immediately work as it should.
Debugging a homemade walkie-talkie begins with improving the quality of signal reception, for which change R10 to a 33-47 kOhm variable resistor and wait until the noise becomes as loud as possible. Now change the level of inductance L5 with the trimmer core, achieving better signal quality, and finally change the variable resistor back to a constant one with the required resistance.
If the timbre of your voice is strongly distorted during signal transmission, select the resistors R1 and R3 more carefully, and to debug the generator and antenna, assemble a wavemeter, the electronic circuit of which is shown below. The basis for the L coil of ten turns of 1.2 mm of wire will be a frame with a diameter of 2.2 cm, where the third turn from the bottom is a tap. Capacitor C1 needs to be made trimmer, with an air dielectric, and its knob should be placed opposite the operating frequency of the signal transmitter of your homemade walkie-talkie, making sure that its L3 coil is next to the L wavemeter coil, thereby making it a kind of indicator. Now, when trying instead of C9 capacitors of different capacities, you need to achieve the maximum deviation of the arrow on the wavemeter division scale, and, bringing the latter directly to the antenna itself and rotating the L1 trimming core, adjust the antenna to resonance with the tuning frequency of the L3C8C9 circuit until the arrow on the wavemeter scale shows the maximum deviation. 
This shortwave radio circuit contains only three transistors. The easiest walkie-talkie to repeat for novice radio amateurs. The design was taken from an old magazine, but did not lose its relevance. The only thing that is outdated is the radio components that need to be replaced with modern counterparts, as a result, the characteristics of the radio communication device will improve.
Radio station diagram
The scheme is simple, especially if you understand its work. I suggest you immediately visually divide it into the left side with one transistor and the right side with two transistors. A transmitter and a receiver are assembled on the VT1 transistor at the same time. When the switch closes contacts "1", the radio is in the receive mode and this transistor operates in the supergenerative detector mode. And when the contacts close into the "2" mode, this is a transmission and the transistor works as a master oscillator. With this, I think it's clear. A simple low-frequency amplifier is assembled on the transistor VT2, VT3, which, depending on the position of the switch, either amplifies the signal from the microphone and transmits it to the transmitter, or amplifies the signal of the supergenerative detector and transmits it to the loudspeaker. By the way, the loudspeaker and the microphone are one and the same element - a high-impedance DEM telephone capsule.Parts for the radio station
Coil L1 is wound on a frame with a diameter of 8 mm with a ferrite core turn to turn and has 9 turns of PEL wire with a diameter of 0.5 mm. Coil L2 is wound over coil L1 and has 3 turns of the same wire. The L3 coil has a diameter of 5 mm and contains 60 turns of PEL wire with a diameter of 0.5 mm. As choke L4, you can use the primary winding of the output transformer of the transistor receiver.Antenna design
The antenna was made by me from a thick aluminum wire, with a piece of insulation, on top of which the L3 coil is wound.
My upgrade
I made such a walkie-talkie back in school, but then I already changed all the transistors to more modern ones with a high gain. For example, I replaced VT1, VT2 with KT361, and VT3 with KT315.Now, of course, I would change the polarity of the power supply and the polarity of the capacitors, replace all the transistors from the n-p-n structure to p-n-p, and p-n-p to n-p-n. Well, I would also install modern transistors. There are no special requirements for transistors, so absolutely any will do.
The author of the scheme says that the radius of action of the same type of radium in an open area is 100-200 meters. I overclocked such radios to 500 meters, for this I used modern transistors, increased the antenna to 900 mm, plus increased the generator current, replacing the 100 Ohm resistor with 50 Ohm. Someone will say that everything is due to the increase in the antenna, with which I disagree and say that with the “native” antenna I was able to communicate at 300 meters.
Customization
If you assembled the walkie-talkie correctly and from serviceable parts, then all tuning will come down to tuning the L1 coil to a frequency of 27 MHz. This can be done with a descender core, or with a capacitor in the circuit.FM TRANSMITTER
In just a couple of days I assembled another interesting device "Fm transmitter". The idea of \u200b\u200ba FM transmitter has been hanging for a very long time, but somehow all hands did not reach the point of manufacturing. The task was to listen to the Moscow FM stations, which are broadcast from the satellite. In this case, do not drive the TV, but receive either a music center or a mobile phone.
I didn't think about the case for a long time - a finished plastic box, and the price is cheap. The entire structure was covered with a 0.3 mm thick tinned brass screen. The screen is simply soldered to the board.
The board is two-sided, installation completely on one side, the second screen, In addition, minus tracks are soldered to the screen
The FM transmitter circuit is a conventional three-point capacitive, the audio signal is modulated by a KV109 varicap, and then goes from the generator to the power amplifier. Everything on common high-frequency transistors 9018. We wind the choke on MLT-0.25 resistors with 30-60 turns of 0.1 mm wire.
The size of the FM transmitter board is 30x50mm. Here you can download the drawings of the boards from the original in the archive.
There were no difficulties in setting up, the transmitter circuit started immediately. The only thing that was selected was two capacities for raising the audio frequency range and a shunt capacitance in the generator, in order to suppress harmonics.
When testing the FM transmitter, I was pleasantly surprised by the work - the sound is crystal clear, the deep lows especially pleased. Frankly speaking, the bass turned out to be velvet. At the same time, there are no hints of the background, in short, like an ordinary FM station, but only in mono mode. The FM transmitter is powered by the receiver itself - it has a 12 volt output behind it for a tulip-type connector, and in the menu there is a 12 V on / off item. The current consumption of the circuit is about 25 mA. Scheme provided by -igRoman-
On a hunt, fishing, on a hike, at work, as a baby monitor or just to communicate with friends ... And this is not the whole list where the radio will come in handy. It is worth saying that it is not difficult to make it, but you still need to have some knowledge in the field of physics and radio electronics.
Naturally, radio components are needed to work:- Transistors (MP 42 - 4 pieces and P416B - 3 pieces);
- Resistors (3K, 160K, 4.7K - 2 pieces each; 22K, 36K, 100K, 120K, 270K - one piece each; 6.8K - 6 pieces);
- Capacitors (10 MK 10V, 3300, 1000, 100, 6, 5-20, 22, 10 - 2 pieces each; 5 MK 10V - 4; 0.0.47 MK - one);
- Telescopic antenna;
- Speaker;
- Microphone;
- Switch, switch;
- 2 textolite boards;
- Wires and wires;
- And of course, a power source, a soldering iron, desire and a little patience.
The next step will be winding the coils on the frame. There are about 200 turns in one winding. 
The presented radio beacon with its own hands can transmit sound over a distance of 500 meters. You can also use it to make an FM tuner and transmit the signal from the phone to the radio.
Kt368 radio transmitter
DIY radio transmitter for kt368
In this article, I want to talk about a single transistor radio transmitter.
It can be used both for wiretapping, as well as make a repeater with it, replacing the microphone, with the audio signal input.
DIY MC2833 radio transmitter
DIY MC2833 radio transmitter
Using the MC2833 microcircuit, you can make a fairly high-quality FM transmitter. This microcircuit contains an oscillator, an RF amplifier, a sound amplifier and a modulator. Available in a miniature plastic SMD package and a standard package.
Do-it-yourself FM transmitter for 1 km and above
DIY FM transmitter for 1 km
This is a powerful enough 2 W FM transmitter that will provide up to 10 km of range, naturally with a well-tuned full-fledged antenna and in good weather conditions, without interference. The scheme was found in the bourgeois and seemed interesting and original enough to be presented to your court))
DIY stereo radio transmitter circuit
DIY stereo radio transmitter
In the car, when it is not possible to turn on music from other sources like radio, and at the same time you want to listen not to what the radio hosts provide, but your own music, as an option, you can use the dIY FM Stereo Transmitter .
The radio transmitter is assembled in a standard plastic case from some kind of device. The front panel has a jack-type audio input and a setting button. There is a power connector on the back. The filter output is connected to the + 12V terminal, so the power cable is used as an antenna. The PCB is secured with only one screw inside the box.
Audio transmitter
DIY audio transmitter (music transmitter)
In this article I want to introduce music transmitter... I tried to assemble a radio transmitter using a varicap in the modulator. Since he was needed to transmit a sound signal, and not a conversation, he put a plug instead of a microphone. Coil 9 turns of wire with a diameter of 1 mm, the middle tap is sealed. I put a small piece of foam rubber inside the coil and dripped it with paraffin (candle) so that the coil would not bend when touched, because the frequency depends on it, and it is very easy to knock it down.
DIY stereo transmitter circuit
Radio stereo sound transmitter circuit
For stereo transmitters there is specialized microcircuit, BA1404.ABOUTpeculiarity transmitter on BA1404 is a high quality sound and improved stereo sound separation. This is achieved using a 38 kHz crystal which provides the pilot tone frequency to the stereo encoder.
A stereo transmitter can be used both in everyday life and in a car, to transmit sound from a carrier (phone, player, etc.), since it does not have a stereo sound transmission.
Such a small stereo transmitter would be a good replacement for an FM tuner.
DIY FM transmitter
FM radio transmitter
Do-it-yourself VHF-FM radio transmitter, works in the unconventional range of 175-190 MHz. This radio microphone is easy to assemble. In order to increase the stability of the master oscillator frequency, the base circuit of the power amplifier transistor is powered by a voltage regulator (R5, LED1).
Used SMD RED Light-emitting diode. Frequency drift when the power supply drops from 3 to 2.2 volts is no more than 100 kHz. When you touch the antenna with your hand, the frequency deviates also slightly. If you have a receiver with a good AFC, it tracks this change and there is no frequency drift during the operation of the transmitter at all.
Do-it-yourself powerful radio transmitter for 500 meters
DIY 500 meter radio microphone
I want to present the design enough powerful radio beetle, Range of action which amounts to 500 meters with line of sight. The device was assembled almost a year ago for our own needs. Beetle showed amazing results: Frequency almost does not float (every 100 meters only 0.1-0.3 MHz). The device does not respond to touches of the antenna and other parts (except for the circuit and the frequency-setting circuit) - this is a very important point, since such a problem is observed in almost all circuits from the Internet.
In the practice of creating radio bugs, we often encounter the problem of the smallest possible bug size. Today we will talk about just such a bug: NEMESIS-2, as it was named. Nemesis was assembled on smd components, due to which it became possible in a significant way reduce size a bug several times, the radio bug is so small that it will fit, for example, in one cigarette, lighter or in a mobile phone. A little about the parameters: the frequency range within 88-108 megahertz, microphone sensitivity about 5 meters, the ticking of the wall clock is heard in the quiet room. So it is easy to receive this signal from this bug to the radio, whether it is on the phone, or just a stationary one. Let's move on to the diagram and details.