[Sjef Verhoeven] still loves radio and enjoys the challenge of listening to radio signals from far away. He wanted to build his own radio and turned to the TEF6686 chip, a device often found in car radios. It is known to be very sensitive and seemed perfect for pulling in weak signals. So [Sjef] built this DIY radio and shares the details in this recent Spectrum post.

Unlike older radio-on-chip devices, the TEF6686 is a DSP, which, according to the post, is part of the reason it is ultrasensitive. Even though it is made for car radios, the device is versatile and can pick up shortwave as well as the usual broadcast bands, with the right configuration.

Initially, [Sjef] wanted to design his own tuner but rapidly found inexpensive modules. These had shielding and through-hole pins, making it much easier to deploy a radio using the chip. The modules run around $25 or less.

The rest of the project centers around an ESP32 and an OLED display, along with switches and encoders. The device requires a host to upload its firmware, so a device with a lot of flash memory was a must. The host must also store fonts for the OLED, and [Sjef] even included a database of ham radio callsigns so that when receiving a North American station, you can instantly see which state or province the station is probably in.

If you want to build a duplicate of this radio, all the details are on GitHub. You can also find kit versions.

If you want to build your own shortwave radio, you could spend more. Or, break out a breadboard, if you prefer.