DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
From a fellow ham radio enthusiast, I recently acquired a refurbished Dell OptiPlex 980. My plan is to turn this vintage desktop into a dedicated machine for amateur digital operations like FT8, a task that doesn’t demand cutting-edge hardware but certainly benefits from stable performance. The system arrived with Windows 7 Pro 64-bit pre-installed, which […]
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.
The uBITX V6.1 is a popular amateur radio transceiver kit. It’s designed for ham radio operators who enjoy building their own equipment. Moreover, it offers great value for money and covers multiple frequency bands. However, like many DIY kits, it sometimes needs tweaking to perform at its best. uBITX V6.1 – My Audio Problem Story […]
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.
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.
The LM1458 is a dual operational amplifier (op-amp) that finds applications in audio amplification and other circuits. Let’s explore how you can create a simple Microphone compressor using the LM1458. To get greater transmitting performance from your ham radio transceiver, we need to keep the modulation level constant, regardless of your voice level. With the compressor […]
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
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
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.
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.