STEMlab RED PITAYA SDR Transceiver Build Part 3

 

In the last instalment of my Stemlab Red Pitaya SDR transceiver project, I completed the design and build of the receiver front‑end module, which includes an RF pre‑amp, bandpass filters, and a digital attenuator. This module improves the Red Pitaya’s receiving performance and adds an extra layer of protection to the Pitaya’s ADC input.

With the new receiver front‑end built and tested, I’ve thoroughly enjoyed listening to the HF bands and evaluating the enhanced performance of the Red Pitaya when integrated with the superb Thetis software.

If you are not familiar with the Thetis software, it is an advanced SDR client originally developed for the Apache Labs ANAN transceivers, and it’s become a popular choice for Red Pitaya‑based SDR projects. It provides a highly configurable interface, low‑latency DSP, powerful filtering, and excellent visualization tools. With features like adaptive noise reduction, customizable panadapter displays, and flexible transmit/receive profiles, Thetis brings out the full potential of the Red Pitaya hardware and offers a polished, professional operating experience.

To continue documenting my SDR transceiver build, this post covers the design and construction of a dedicated controller that enhances and complements the Red Pitaya module, the heart of the project.

STEMlab RED PITAYA SDR Transceiver Build Part 2

Now that the Stemlab Red Pitaya 125-14 module has been modified for use as an SDR (software defined radio), it is time to design and build a front end module with filtering, RF amplification and digital attenuation.

The Red Pitaya board has very wideband, high-speed ADC's that will digitize everything from DC up to tens of MHz and while this is desirable for a software-defined radio receiver, it is not without some downsides.

A Multimode Radio Transceiver Modulator

Following on from the last blog post that I made in July 2024, I present the progress I have made with the microphone preamplifier stages for the Irwell HF Transceivers modulator.

As per usual time has moved on and I have been sidetracked by other projects but with that said, the Irwell HF Transceiver project is and has always been a long-term project.

Since my last update, I have produced and developed various prototype circuits in a bid to get the modulator finished, some of which are illustrated below.

Microphone Pre-Amplifier For The Irwell HF Transceiver

Back in October 2022, I posted details on the blog of a "High Performance AM, CW & SSB Modulator for the G6LBQ Irwell HF Transceiver" this module was somewhat experimental and, for me, a practical introduction to the MC1496 modulator IC. The module contained no microphone amplifier stages, as it was my intention to add these as a separate module at a later date.

  To view my 2022 Modulator blog post article, click here.

In this blog post, I get to grips with the microphone preamplifier and share some of my design methods and thought processes along the way.  Note it is not my intention to provide a step-by-step guide to the design but more of an insight and reference.

The success of this module is crucial in order that I can continue the development of the final transmit stages and achieve finished project status.

A High Performance HF Transceiver RF Subsystem.

 

In this blog post I bring some of the completed "Irwell HF Transceiver" modules together and consolidate them on to a single PCB.