DIY 180-230MHz FM Transmitter Guide

There are many people online who use transistors for high-frequency oscillation, but this article shows another method. If you're interested, feel free to keep reading.

You can also use the MOSFET 2SK241 to make a high-frequency oscillator. With this oscillator, you can DIY an 180–230 MHz FM signal generator and transmitter. Once each part is soldered, you can power it on and test it. If it works, you're good to go.

For the finished product's appearance, you can make a case out of a piece of iron, as shown in the figure below:

The internal structure after assembly looks like this:

The oscillator and power amplifier need to be isolated:

The circuit board section looks like this:

The oscillator coil section:

Power amplification section, as shown below:

Oscillator power supply regulation, as shown below:

The 180–230 MHz FM schematic diagram is as follows:

L1 and L2: use 1.9 mm diameter enameled wire, wound 7 turns on a 6 mm drill bit.

L3 and L6: use 0.8 mm diameter enameled wire, wound 7 turns on a 6 mm drill bit.

L4: use 0.8 mm diameter enameled wire, wound 2 turns on a 6 mm drill bit.

As for reception, the frequency drift due to temperature isn't too bad. After running overnight, it drifted about 180 kHz. You can test the transmission distance yourself later.

The End.