Previuos posts:

• KeithSDR Transceiver [Part 1]: Building the software
• KeithSDR Transceiver [Part 2]: Testing the display
• KeithSDR Transceiver [Part 3]: Main board, power and encoders
• KeithSDR Transceiver [Part 4]: The RF Receiver

Summary

In this post, I will cover the audio path of the KEITHSDR build and show the final assembly of all components inside the enclosure. After confirming the reception path, it’s time to ensure the audio signals are properly routed and amplified, then finalize the hardware setup and reception test.

Previuos posts:

• KeithSDR Transceiver [Part 1]: Building the software
• KeithSDR Transceiver [Part 2]: Testing the display
• KeithSDR Transceiver [Part 3]: Main board, power and encoders

Summary

In this post, I will focus on the reception side of the SDR radio. Although KEITHSDR support various transceiver modules, many are no longer available. Some alternatives could be adapted, provided they offer I/Q output and can be controlled by the Teensy microcontroller.

For my build, I chose to begin with the QRP Labs receiver module, which is already supported by KEITHSDR and I’ll figure out the transmission part later.

This is the third part in the build process for the KeithSDR transceiver. Following on from parts 1 and 2 [placeholder link to part 1] and [placeholder link to part 2], this stage focuses on integrating the core components onto the main printed circuit board (PCB). We’ll be installing sockets for the Teensy and Audio hat, mounting the display with spacers, and setting up the I2C encoders and power supply.

In KeithSDR Transceiver [Part 1]: Building the software Building the software][KeithSDR Transceiver [Part 1]: Building the software]] I have installed the Arduino IDE, Teensyduino and I have successfully compiled and upload the software of the KeithSDR receiver.

Next I am trying to test the display.

Testing the display

:PROPERTIES: nil:END: To test the display I decided to use a breadboard to connect the display SPI interface to the Teensy, following this schematic. Then, I connected the Teensy to the laptop and I inspect the debug messages in the serial monitor to see if the Teensy recognizes the display.

Summary

I obtained my Radio Amateur license recently but I don’t own any HF radio that I can operate at the moment. I was looking for a HF transceiver I can build myself and I came across the KeithSDR project. KeithSDR is basically a SDR transceiver built using a Teensy 4.1 as main CPU board, a RA887X display and and RF receiver or transceiver capable of providing an I/Q audio output. The project does not include details on the construction of the RF receiver/transmitter but relies on existing RF receivers or transmitters.