Many have portable radios. It is not a problem to buy them in the store, but ground obstacles, wires and metal objects often interfere with their work. But you can assemble a stationary walkie-talkie of low power with an increased range. It can stand at home or in the country, and a good antenna will increase its range up to 5-10 km in any conditions.
It is necessary
- - parts from an old tube radio or TV;
- - soldering iron;
- - accessories for soldering;
- - aluminum sheet.
Instructions
Step 1
Make a U-shaped chassis out of aluminum sheet, taking into account the dimensions of the parts you have. Equip it with a vertical aluminum front panel. It will be possible to place the controls on it. Take the power supply ready from the radio, TV, radio, etc. It is necessary that it give a constant anode voltage of 150-250V and a filament voltage of 6, 3V.
Step 2
Assemble the walkie-talkie according to the transceiver circuit, as shown in the figure. The coil of the transceiver loop is made of copper wire with a diameter of 1 mm. Take a bare wire, or even better - silver plated. For the range of 27-30 MHz, it is wound on a rod with a diameter of 12 mm, and it contains 4 turns with a tap in the middle.
Step 3
The coil of communication with the antenna contains 1-2 turns of the same wire and is located on top of the coil of the loop. Wrap the chokes Dr1, Dr2 and Dr3 on the resistances ВС-0, 25 with a resistance of at least 1 mOhm. They contain 0.5 m each of PEL-0.15 wires.
Step 4
The tuning capacitor C can be taken with a ceramic 4-15 pF (trimmer), but it is better if it is with an air dielectric with one movable and two fixed plates. If you are going to work on only one specific channel, then you will not need to supply it with a tuning knob.
Step 5
Take transformer Tr1 (sound transformer TVZ or a similar output tube) from a tube receiver or TV. A high-resistance winding of exactly the same transformer is used as a choke Dr6. If you want to use low impedance headphones, plug them into the low impedance winding of this transformer. The diagram below shows the inclusion of high impedance telephones.
Step 6
Use a carbon microphone. For example, from a telephone set. As a "Receive - Transfer" switch, wafer switches are suitable. They can be replaced with any others for 3 contact groups and 2 positions.
Step 7
Tune to a radio station. Tune in receive mode. Use the variable resistor R3 to achieve stable super super noise at all positions of the tuning capacitor. If this cannot be achieved, select the capacitance of the capacitor C3 in the range from 100 to 1000 pF. Tuning over the range is carried out with a capacitor C, as well as shifting and expanding the turns of the loop coil. When the tuning frequency coincides with the carrier frequency signal, super noise in phones should be completely extinguished. When switching to gear, the sound from the microphone should be clearly audible in the monitoring radio.
Step 8
Select the position of the communication coil with the antenna so that the transmission power is maximum, and the reception is stable. An already tuned pocket radio can be used as a monitor receiver and transmitter.
