With this simple device called a converter, you can receive FM radio stations in the 88-108 MHz range on a 52-72 MHz radio. You can also receive 123-143 MHz signals on an 88-108 MHz radio. In fact, these frequency ranges can be easily shifted up or down.
How does this device work? The device is a generator on a transistor that produces a signal with a frequency of, say, 30 MHz. If you connect an 80 cm long antenna to the gate of the transistor, then FM signals from broadcast radio stations will arrive at this gate, say, with a frequency of 100 MHz. The converter either subtracts two signals of 100 MHz – 30 MHz = 70 MHz, or they are summed up by 100 MHz + 30 MHz = 130 MHz. On a radio receiver that receives signals at frequencies of 50-70 MHz, you can receive signals at 88-108 MHz.
The converter coil contains 7+4 turns of wires with a diameter of 0.6 mm, wound on a mandrel with a diameter of about 5 mm.You can wind a different number of turns, but the frequency range will shift.
When the converter is turned on, a signal with a frequency of about 36 MHz should appear on capacitor C2. But it does not have to be exactly 36 MHz, the frequency can be several MHz higher or lower.
Be sure to connect a 50 Ohm coaxial cable to capacitor C2 that will connect to the radio receiver antenna, this is necessary so that the output signal of the converter is not radiated and not goes to the converter antenna. You can connect the converter output to the radio receiver antenna without a cable, if you can afford it
I checked the operation of the converter with a radio station, the transmission frequency of which was 130 MHz. I received the signal from the radio station on the radio receiver at a frequency of about 95 MHz
