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This article details the design and construction of a compact 20-meter QRP SSB transceiver by Pete Juliano, N6QW, measuring just 2 x 4 x 2 inches—small enough for a shirt pocket. Inspired by a 1963 QST design and refined from a prior version, it employs bilateral circuits, a 4.9152 MHz homebrew crystal filter, switched-crystal VXO for 60 kHz coverage (14.160-14.220 MHz), and standard components like ADE-1L mixers and IRF510 PA for 1W output. Key innovations include a double-sided PCB skeletal frame for shielding and isolation, Vectorboard sub-assemblies, and ultra-miniature relays. The bilateral receiver/transmitter shares stages, omitting AGC for simplicity, while a W3NQN LPF and optional 10W external amp enable DX contacts. Tune-up focuses on crystal matching and bias for linearity. Videos on YouTube demonstrate performance, confirming excellent stability and audio. Total cost nears $100, prioritizing portability over features like CW.

Many low-power SSB rigs and kits lack dedicated speech processor circuitry, although most modern HF rigs include it. Speech processing is crucial for low-power SSB to overcome QRM. This simple, low-cost circuit integrates a microphone element and can be housed in a defunct desk mike. It features a feedback amplifier, audio preamplifier, and adjustable speech compression control

Single Sideband (SSB) operation requires careful attention to the relationship between a radio's displayed frequency (suppressed carrier) and the actual 3 kHz wide audio signal. This resource clarifies how Upper Sideband (USB) and Lower Sideband (LSB) signals occupy spectrum above or below the indicated frequency, respectively. It provides practical examples for General Class operators on the **20m** and **40m** bands, such as setting a VFO to 14.226 MHz for USB on 20m or 7.178 MHz for LSB on 40m, to maintain a safe margin from band edges. The resource emphasizes the critical importance of staying within allocated band limits to prevent out-of-band emissions, particularly when operating close to band edges. It includes relevant excerpts from **FCC Regulation Part 97**, specifically section 97.307, which details emission standards, necessary bandwidth, and spurious emission attenuation requirements. The text explains that unused sidebands are considered spurious emissions and notes that modern HF equipment typically exceeds the 43 dB spurious emission reduction standard, often achieving 60 dB or more.

Single-sideband (SSB) radio enhances spectral efficiency but poses challenges with audio intelligibility, particularly in noisy conditions. A microphone audio compressor addresses these issues by dynamically managing the audio signal’s dynamic range. It amplifies quiet sounds and attenuates loud ones, ensuring consistent audio levels for improved clarity. Benefits include increased intelligibility, higher average power, and reduced spurious emissions. While essential for optimal SSB performance, careful parameter adjustment is crucial to balance natural sound quality and effective communication across various operating modes.

The NRC Archives feature past DX News and DX Audio Service publications, offering a glimpse into the "Heyday" of BCB DX. Subscribe to DX News for essential information, 20 bulletins annually, and membership privileges with discounted NRC products. New visitors can download a free sample copy of DX News

SWLTools, an iOS application for iPhone and iPad running iOS 17+, provides real-time decoding of various digital modes. It automatically locks onto CW tones, measures sending speed, and collects callsigns, distinguishing valid entries from misreads for a reliable log. For RTTY and SITOR-B, the app allows users to set shift and speed, then automatically tunes to the two tones for text reception, supporting marine bulletins, press agencies, and NAVTEX. The application also decodes WEFAX, building charts line by line for direct saving to the photo library, and processes ACARS aircraft messages, including CRC checks for data integrity and mapping of position reports. Beyond decoding, SWLTools integrates a GPU-accelerated FFT spectrum analyzer, a scrolling waterfall display with frequency cursors, and an adjustable FIR bandpass filter to isolate signals. It supports IQ signal analysis from receivers via two-channel audio interfaces, correcting mirror images. Flexible audio input options include the built-in microphone, USB audio dongles, and Bluetooth sources, with diagnostics for audio routing and buffer status. The app records audio, plays it back, and converts recordings into shareable videos, while decoded texts and charts are also savable and shareable, with all timestamps in UTC.

Learn how to eliminate RF interference from your Behringer HA400 headphone amplifier for a better listening experience. Discover the simple modifications needed to prevent distortion caused by RF in your audio setup. Follow the step-by-step instructions provided by WB5NHL Ham Radio to improve the performance of your headphone amplifier in ham radio activities.

Demonstrates _FreeDV RADE_, an open-source digital voice mode for HF, which combines machine learning with classical Digital Signal Processing (DSP) to achieve improved speech quality and spectral efficiency. Released in June 2025 by ARDC grantee FreeDV, RADE operates at Signal-to-Noise Ratios (SNRs) as low as -2 dB and occupies approximately 1.5 kHz of bandwidth, half that of a typical SSB signal, while transmitting about 8 kHz of voice audio. The mode also features an optimized Peak-to-Average Power Ratio (PAPR) for efficient power amplifier use, reducing heat and consumption. Users, such as _VK3TPM_, report significantly improved listening ease compared to analog modes, particularly in high HF noise environments, making it easier to conduct nets across various Australian states. The mode's integration into popular radios like the _FlexRadio 6000_ series allows direct operation without external computers. A C library for RADE is available, facilitating broader integration into other radios and SDR programs, with development continuing on FreeDV RADE v2 to further narrow bandwidth below 1 kHz.

The Florida AM Group operates a weekly Amplitude Modulation (AM) net on 3885 kHz every Sunday morning, with a pre-net starting at 6:30 AM Eastern Time and the formal net at 7:00 AM. This group focuses on the preservation, restoration, and on-air operation of antique Amateur, commercial, homebrew (HB), and Military Radio equipment, emphasizing **Amplitude Modulation** (AM) mode. Participants are encouraged to use AM mode, regardless of whether they possess vintage gear, fostering a community around classic radio operation and the distinctive high-fidelity audio associated with **vacuum tube** equipment. The net utilizes NetLogger software for check-ins and round table management, providing a structured environment for participants. The group regularly publishes net control schedules, listing operators like NZ1Q, K1HH, and W3XM, and organizes various in-person events such as Hamcation gatherings, luncheons, and boat anchor swap meets. These activities facilitate eyeball QSOs and equipment exchanges, reinforcing the community aspect beyond on-air operations. The Florida AM Group also provides contact information for net control volunteers and shares news, including SK (Silent Key) announcements for members like Steve KI4RUS and Roy W4IDD, highlighting the group's long-standing camaraderie and shared passion for AM radio.

Decoding Morse code from visual sources like screenshots, scanned documents, or photographs presents unique challenges compared to audio-based reception. This web-based utility addresses these by allowing users to upload or paste images containing Morse code, which is then processed entirely within the user's browser, ensuring privacy. The tool identifies individual marks, classifying them as dots or dashes, and estimates letter and word spacing to generate an editable Morse draft. Users can refine the detection by utilizing controls for cropping, rotation, contrast boosting, and manual threshold adjustment, which are crucial for overcoming issues like low contrast, skewed baselines, or extraneous graphics. After the initial detection, the generated Morse draft, such as _... --- ... / .... . .-.. .--?_, can be manually corrected before being translated into plain text. The system provides confidence indicators and warnings to highlight potential ambiguities in the decoded output, prompting users to review and make necessary edits. This specialized approach differs from general OCR engines by focusing on the distinct patterns of Morse marks and gaps, rather than attempting to read standard alphanumeric characters. The tool supports common image formats like PNG, JPG, JPEG, and WebP, and includes sample images for benchmarking its performance, demonstrating its capability to handle various image qualities and complexities.

The article details how to eliminate Radio Frequency Interference (RFI) from the Behringer HA400 headphone amplifier when used in ham radio setups. While the HA400 is praised for its quality and affordability, it was not designed for RF environments, causing distortion when used with a 500-watt radio station. Initial attempts using clamp-on ferrites on the headphone and power cables only partially resolved the issue. Upon opening the unit, the author discovered the circuit lacked RF bypassing components. The solution involved installing 0.1μF (104) capacitors at key points in the circuit: the power supply input, audio circuits, and op amp inputs. This modification, combined with the external ferrites, completely eliminated the RFI problem, making the unit suitable for ham radio operations.

Optimizing on-air audio for SSB, DXing, and contesting operations is addressed through a range of specialized audio processing equipment. The offerings include multi-band equalizers, specifically 5-band, 8-band, 10-band, and 12-band units, some integrated with features such as compressors, echo effects, noise gates, and phase rotation capabilities. These devices are engineered to interface with common amateur radio transceivers, with explicit compatibility noted for models like the Yaesu FT-DX10, FT-DX101D, FT-1000MP, FT-DX5000, Collins HF-380, and Flex 6300, alongside analog S/P meters for Icom rigs. The product line focuses on enhancing microphone audio characteristics, supporting XLR dynamic microphones for improved signal clarity and presence. The manufacturer, DB6QW Electronics, emphasizes direct support and a 100% manufacturer's warranty, reflecting confidence in product quality and operational reliability. This resource details specific audio processing tools designed to refine the transmitted audio signal, providing operators with granular control over their voice characteristics for competitive and casual amateur radio communications.