Hobbyist radio can encompass quite a few specific kinds of transmitters and receivers. “Ham radio” alone is a broad term that includes many types of communications. Usually, ham radio operators have elaborate setups and are registered with call signs to meet FCC regulations. But if you just want to experiment with simple radio transmissions, it’s easy enough to build your own FM radio transmitter. In this guide, Hesam Moshiri explains how you can do that.
Before we go into more detail, it’s important to point out that radio transmissions in most frequencies are highly regulated. That’s especially true in the FM spectrum, and you can easily get into trouble by broadcasting without permission. For that reason, it’s very important that you don’t amplify the output of this device. If the broadcast can be picked up by anyone else, then you’re breaking the law. But as long as you’re clear on your local regulations and are careful to adhere to them, this can be a fun weekend project.
To build Moshiri’s FM transmitter design, you’ll need a VMR6512 chip. That can transmit anywhere from 88.0MHz to 108.0MHz, and all of the necessary radio circuitry is built right into the chip. All of the other components on Moshiri’s custom PCB are for controlling that chip and to provide inputs and outputs. If you don’t want to order a PCB, you can also wire the chip up on a breadboard. This design has an SMA connector for the antenna, but you can really use whatever you want for an antenna.