Radio transmitter 27MHz power 300mW on transistor 2222

I assembled this radio transmitter on two transistors at a frequency of 27 MHz so that beginners could repeat it, and the transmitter would have an acceptable range. I will also tell you in detail how to set it up and how to make the antenna correctly

A radio transmitter is assembled on a 2222 transistor, its frequency is stabilized by a quartz resonator at a frequency of 27 MHz. A modulator is assembled on a KSE800 transistor, through which power is supplied to the transmitter and sound is mixed in at the same time. Amplitude modulation occurs.

Coil L1-L2 are wound on a frame with a diameter of 5 mm with a wire with a diameter of 0.3 mm. First, wind coil L1, it contains 15 turns and wind L2 on top of it, it contains 4 turns. For tuning, you need a ferrite rod with a diameter of about 0.3 mm, which is screwed into the frame. I do not know the brand of ferrite, I just took the first one that came to hand.

Setting up. Connect a 50 Ohm resistor with a power of 0.5 W or other power to the L2 terminals. The resistor must be non-inductive. This is the load resistor. Connect the oscilloscope probe to this resistor, switch its division to 10. Screw the ferrite into the coil frame and achieve the maximum signal amplitude, the resistor should heat up. If the signal amplitude is around 1.44 Volts, then this will be normal

Assemble an RF probe from two diodes and an LED. Touch the probe lead to a 50 ohm resistor and the LED should light up brightly. This completes the first stage of setup

The GY561 device shows a radio transmitter output power of 300 mW into a 50 ohm load at a frequency of almost 27 MHz. This 50 ohm load is inside the device

Now the second stage of tuning, it will already be connected with the antenna connection. The antenna must be made. It is better to use the Nanovna antenna analyzer to tune the antenna. Make a dipole antenna from a wire with a diameter of about 1.3 mm. Each dipole arm is 2 meters 55 centimeters long. The distance between the arms is about 4 centimeters. Connect a coaxial cable with a resistance of 50 Ohm to the arms. You can put a ferrite on the cable where the cable is connected to the dipole arms. Solder the cable to the terminals of the L2 coil and place the antenna away from long metal objects, otherwise part of the power will be spent on them

Take the HF probe and place it near one of the antenna arms. Insert the ferrite core into the coil frame and achieve maximum glow of the probe LED. This will mean that the antenna emits maximum signal power. If the radiation is weak, swap the terminals of the L2 coil. This completes the setup and it is time to check the range of the transmitter.

By the way, the antenna is shown in the photo, and you can see the ferrite on the cable and how the dipole arms are located. I walked with a tecsan radio receiver and received a signal from a radio transmitter at a distance of 1 kilometer, the antenna was on the balcony of the 10th floor