Explore MSI-SDR — a budget wideband SDR receiver with 12-bit ADC, up to 8 MHz bandwidth, and multi-band inputs, offering hobbyists a cheap entry into RF spectrum analysis
Author: Prabakaran
Prabakaran is a seasoned author and contributor to leading electronics and communications magazines around the world, having written in publications such as Popular Communications Magazine (USA), ELEKTOR (UK), Monitoring Times (USA), Nuts & Volts (USA), and Electronics For You (India).
Terminated Antennas for HF Ham Radio: A Technical Guide
This guide explains terminated antennas for HF ham radio, which use resistors to absorb reflected energy and maintain stable impedance across wide frequency ranges. It covers designs like Beverage and T2FD antennas, highlighting their broadband performance, directional patterns, and suitability for multiband, low-noise, and space-restricted installations.
Terminated Mini Loop Antenna : Small Space Ham Radio Antenna
This article explains a terminated mini loop antenna designed for small spaces, combining loop geometry with resistive termination to achieve directional reception and reduced noise. It covers construction using wire, a terminating resistor, and a matching transformer, delivering wideband HF performance without a tuner for compact installations.
Microphone Audio Compressor in Single Sideband Radio
This microphone audio compressor for SSB radio combines a low-noise preamplifier with automatic gain control to maintain consistent speech levels. It boosts weak audio and limits peaks, improving average modulation and clarity without distortion, making transmissions more intelligible, especially in low-power HF setups.
Can You Use MXR Dyna Compressor for SSB Radio?
This article explains why the MXR Dyna Comp, a guitar compressor pedal, is not suitable for SSB amateur radio use despite being a compressor.
It points out key issues like impedance mismatch, since guitar pedals expect high-impedance inputs unlike microphone or line-level signals used in transceivers. It also highlights that the pedal’s frequency response and controls are designed for musical audio, not narrowband voice signals used in SSB.
Condenser Mic audio amplifier – DIY Guide
The compact, low-cost condenser mic amplifier described here give good-quality audio of 0.5 watts at 4.5 volts,used in walkietalkies, low-power transmitters
Dual microphone noise cancellation using LF351 Op Amp
This dual-microphone noise cancellation circuit uses two microphones placed back-to-back, with one signal inverted and summed using an LF351 op-amp to cancel common ambient noise. It preserves the desired voice signal while reducing background noise, improving clarity in noisy environments
Series Modulated AM Transmitter
This series-modulated AM transmitter uses a simple low-power design where the audio signal is applied directly to the power supply of the RF oscillator, causing the carrier amplitude to vary and produce AM. It uses a crystal oscillator for stable frequency and is ideal for beginners learning basic radio transmission concepts.
Class C – AM Transmitter
This Class C AM transmitter uses a high-efficiency amplifier where the transistor conducts for less than half the signal cycle, achieving around 70–80% efficiency. It combines an oscillator, buffer, and IRF510 MOSFET power stage to deliver about 5 W RF output, making it suitable for compact amateur radio transmission.
Noise Cancelling Condenser Microphone
This noise-canceling condenser microphone design uses dual electret microphones with op-amp stages to reduce ambient noise. One mic captures the desired audio while the other picks up background noise, which is inverted and summed to cancel interference, improving clarity for communication and recording.