DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
“DIY” on DXR Electronics Bits is where practical ham radio projects come to life. Here you’ll find buildable circuits, antennas, receivers, preamps, audio tools, and experimental rigs designed for real‑world shack and field use. From compact HF antennas for small spaces to regenerative receivers, QRP transmitters, and uBITX add‑ons, each article focuses on parts you can actually source and solder on the bench.
This micro power AM transmitter uses a crystal-controlled oscillator and a 2N2222 transistor stage to generate a stable RF carrier, then modulates it with audio input. A tuned tank circuit and variable capacitor optimize output, enabling low-power short-range broadcasting for experimentation and learning
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 […]
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 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.
This microphone compressor circuit utilizes a two-stage amplification design for dynamic range control. Initially, the input signal enters through MK1, a microphone input connector. Subsequently, the signal passes through C1 and C3 coupling capacitors for DC blocking. The first amplification stage employs Q1, a 2N3904 transistor configured as a common emitter amplifier. Meanwhile, R1 provides […]