Simple 2N3904 microphone preamplifier for uBITX V3–V6 transceivers that fixes low mic audio and restores full transmit power. Powered from the MIC+ line with adjustable gain for clean, natural SSB modulation.
Transmitter
The Transmitter category focuses on RF circuits that actually put a signal on the air: from simple QRP rigs and short‑range AM broadcasters to more advanced HF drivers and linear stages. You’ll find classic experiments like the Ten Minute QRP transmitter and Mighty Mite, educational HF and short‑wave transmitters, as well as modern solid‑state designs such as Class‑C AM transmitters and IRF510 push‑pull power amplifiers.
Each article explains the full RF chain in practical language—oscillator, buffer, driver, PA, filtering, and modulation—so you see how the blocks fit together instead of just copying a schematic. Wherever possible, circuits are crystal‑controlled or otherwise stabilised, with notes on heatsinking, harmonic suppression, legal use, and how far you can realistically expect to be heard. Whether you want to understand the theory behind AM and CW transmitters, build a low‑power beacon, or develop the RF stages that will later become a full transceiver, this section gives you proven starting points and measured results to guide your experiments.
DIY HF Linear Push-Pull Amplifier with IRF510 MOSFETs
Learn how to build a high-performance HF Linear Push-Pull Power Amplifier using affordable IRF510 MOSFETs. This guide includes a full schematic, bias adjustment tips, and transformer winding details for 10-40W output across the HF bands.
Near Vertical Incidence Skywave (NVIS): The Definitive Guide to Reliable Regional HF Radio
This article will give you a complete understanding of NVIS propagation. With the level of technical expertise and detail found in this article, this guide is intended for the amateur radio operator who wants to go beyond the theory and learn the details of NVIS antenna design and operations.
Mighty Mite 5W Crystal Controlled QRP CW Transmitter
The Mighty Mite 40 Meter QRP CW Transmitter is a legendary low-power Morse code transmitter widely built by amateur radio operators for portable, minimalist, and educational operation.
Building Sovina 40M Class E CW Transmitter with BS170 MOSFETs
Build the Sovina 40 m Class-E CW transmitter using BS170 MOSFETs and 74HC02 logic for efficient 7 MHz QRP operation. High-efficiency switching PA delivers 4–7 W output with clean RF and simple crystal-controlled design for homebrew HF rigs.
Build a Powerful FM Radio Bug Transmitter
Three-stage FM bug transmitter using BC547 audio preamp, RF oscillator/modulator, and 2N3563 power amplifier for strong 100 MHz transmission. High-performance DIY wireless microphone circuit with improved range and signal stability.
DIY 1 MHz AM Transmitter: A Perfect Weekend Project for Beginners
Basics of radio frequency by building a simple 1 MHz AM Transmitter. This guide explains the circuit design and secrets of amplitude modulation for hobbyists
The Simple RF Indicator: A DIY Tool for Detecting RF Signals
The image depicts “Simple RF Indicator,” passive device for detecting radio frequency (RF) signals in coaxial cables. It’s a clever hack using basic components
Tiny FM Transmitter with Just a Few Easy-to-Find Components
Learn how to build a compact Tiny FM transmitter using 2N3904, a few passive parts, and a simple air-core coil. Perfect for DIY electronics enthusiasts
27MHz AM Transmitter Circuit for hobbyists
The 27MHz frequency band has long been a favorite among electronics enthusiasts and amateur radio operators. This citizen’s band frequency offers excellent propagation characteristics and serves as an ideal starting point for understanding amplitude modulation (AM) transmission principles. Today, we’ll explore a well-designed 27MHz AM transmitter circuit that demonstrates classic RF engineering concepts while remaining accessible to hobbyists

