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A collection of audio amplifier projects by N1HFX

Listen to Cleveland Police Dispatch and Metro Housing Authority via the Live Audio Feed Web Player

Kenwood TM-201/401 Increased TX Audio, mod for microphone gain

The CAT and audio interface version 3 project by PA5CA presents a comprehensive solution for integrating amateur radio transceivers with computer sound cards, facilitating digital mode operation and CAT control. It includes detailed schematics for the interface circuitry, illustrating the isolation transformers for audio paths and optocouplers for CAT data lines, ensuring robust electrical separation between radio and PC. The resource also provides PCB layouts, enabling constructors to fabricate their own boards for this specific design. The project outlines the component selection and assembly process, emphasizing the use of readily available parts to build a reliable interface. It addresses common challenges in sound card interfacing, such as ground loops and RF interference, through its isolated design. This construction guide offers practical insights into building a functional interface, making it suitable for hams interested in DIY radio accessories for digital modes like FT8, RTTY, and PSK31.

Demonstrates the product line of CAIG Laboratories, focusing on specialized contact cleaners and lubricants essential for maintaining electronic components. Key products include **DeoxIT**, designed for deoxidizing and protecting electrical connections, and **DeoxIT Gold (ProGold)**, formulated to enhance conductivity and provide long-lasting protection on plated surfaces. Details the application of these solutions across various electronic devices, from audio equipment to critical ham radio gear, ensuring optimal signal integrity and component longevity. The product range also features **DeoxIT Faderlube (CaiLube MCL)**, specifically engineered for conductive plastic and carbon-based controls, mitigating wear and improving tactile feel. Explains how proper contact maintenance with these products can prevent intermittent connections, reduce noise, and extend the operational life of switches, potentiometers, and connectors in both commercial and amateur radio applications.

AudioXplorer is a sound analyzer software designed for Mac OSX, provide a real-time analysis window where you can visualize the sound spectrum and sonogram

Gold Line, a manufacturer, provides a range of professional audio test and analysis equipment, including specific products like the **ZM1 Impedance Meter**, which is relevant for amateur radio operators needing to characterize antenna systems. The site also lists various noise sources and microphones, such as the TEF04 Mic, indicating a focus on audio signal integrity and measurement. The resource details contact information for repairs, calibration, quotations for specific products like the ZM1 and ZM1P, and technical support, with distinct email addresses and phone numbers provided for each function. This structured contact approach facilitates direct engagement with the appropriate department for specific inquiries. Operational changes effective March 1, 2019, are noted, directing users to VLDESIGN for repair and calibration, and to Partha Chen for ZM1/ZM1P quotations. Louis Pittsley is designated for technical support, with a general inquiry phone number also available, outlining the company's support infrastructure.

remoteAudio is an multi platform Audio streaming application for Amateur Radio purposes. The most typical use case for this software is the remote operation of an amateur radio station. remoteAudio supports multiple users and multiple audio sources. At any time multiple clients can listen simultaneously on the same radio, although remoteAudio only allows one user to transmit.

Constructing a digital interface for the Elecraft K2 transceiver, this resource details the "Fat Wire" design by WG4S. It demonstrates how to integrate a sound card for digital modes, outlining specific connections to the K2's microphone jack and internal audio path. The author shares practical insights from his build, including the use of _RG-62_ coax for its flexible braid and the strategic placement of components like the 2.2K resistor and _2N2222_ transistor. The guide provides a breakdown of the interface's internal wiring, specifying connections for AF In (pin 1), AF Out (pin 5), PTT (pin 2), and Ground (pin 7) on the K2's microphone connector. It also covers the external connections to a laptop's headphone and line-in jacks, along with a DB-9 connector for PTT control via _DTR_ or RTS lines. The author notes that his laptop's headphone output level was sufficient for the K2, negating the need for an attenuator. Reflecting on the design, the author, Dan WG4S, acknowledges a later suggestion to house the components directly within the DB-9 shell for a more compact build. This iterative feedback highlights the ongoing evolution of DIY ham radio projects and the community's collaborative spirit in refining designs.

Battery-powered monitor designed to provide an audible indication of keying for those whose rigs lack a CW sidetone

The SDRanywhere application is an Android app that allows remote operation of an RFSPACE SDR-IQ, NetSDR, SDR-IP or Cloud-IQ radio from anywhere in the world. The demodulated audio and waterfall information is compressed and sent to the client application using a low bandwidth internet connection.

collection of vintage audio equipment

Windows PC control program for the Icom IC-7300 transceiver. Power-on and Power-off by software BktNetInterface for JTDX and WSJT-X, audio recording, memory management, cw keyer management, Interface for other software

A very informative review of the Icom IC-7300 direct RF sampling transceiver, including audio samples, recordings and a comparison vs the Elecraft KX3

W1AEX Audio settings and general observations

Installing the Cumbria Designs X-Lock VFO Stabilizer, and Improving The TR7 Audio Quality

This page has a collection of audio samples from unusual HF propagation phenomena, from round-the-world propagation to moonbounced signals , and to ducted transmission.

MorseExpert 1.15 decodes Morse Code audio to text, leveraging algorithms from CW Skimmer for optimal performance on weak, fading signals amidst interference on amateur radio bands. It processes audio from the device's built-in microphone or an external radio receiver via cable, optionally highlighting Ham callsigns and keywords. The application features a waterfall display with a bandwidth of 200-1200 Hz, decodes frequencies between 300-1100 Hz, and supports keying speeds from 12-45 WPM with automatic CW pitch detection. Recent updates include support for Android 15, edge-to-edge mode, improved stability, and a pause decoding button. A premium version offers an ad-free experience and user-selected text colors. Users can switch between General Text mode and Ham Radio QSO mode, which enhances word segmentation and highlights callsigns. The app also includes a frequency lock mode, text selection capabilities for copying, sharing, or saving decoded text, and provides guidance on reducing acoustic echo and constructing an audio attenuator for optimal radio interfacing.

International Public Access Radio via IRRS Shortwave and Internet Radio NEXUS via MP3 streaming audio

The Shortwave Radio Audio Archive is a collection of shortwave radio recordings in both the form of a podcast and blog with embedded audio. The collection grows every day and includes both historic and modern day shortwave radio audio recordings

Operating the UoSAT-2 (OSCAR-11) satellite, launched in 1984, presents unique challenges due to its age and current eclipse schedule. This resource provides a historical archive of news, telemetry data, and specialized software for decoding its 145.826 MHz FM beacon. It includes tools like _CTERM_ for terminal emulation and capture, and U2TM for processing ASCII telemetry, enabling hams to analyze the satellite's health and performance. The site also offers audio samples of the beacon and S-band signals, along with details on hardware and software decoders. Reception reports are actively solicited for the satellite's intermittent transmissions, which occur for less than an orbit every 21 days during its eclipse period. The site details how to process raw telemetry data, including instructions for skipping initial frames to improve decoding accuracy with U2TM. It also provides software like SATILL for predicting solar eclipses and tools for determining the satellite's spin period from magnetometer or solar array telemetry, offering insights into its operational status despite its advanced age.

This project is an APRS iGate for digipeater aboard the ISS. As the ISS pass over the iGate location, the TNC decoded the audio tones and creates data packets the Raspberry Pi can receive.

Right Mark Audio Analyzer is a suite designed for testing quality of any audio devices, be it a sound card, an MP3 player, a consumer CD/DVD player or a radio.

Jose B Rivera, N2LRB, shares his initial experiences with the Icom IC-7300, recounting a shift from skepticism to appreciation for the transceiver. He details how the radio's impressive Sherwood Engineering test results, ranking it #12, significantly influenced his decision, especially considering its competitive price point against higher-end options like the Elecraft K3s. The review highlights the IC-7300's strong receive capabilities, a key factor in N2LRB's purchasing decision, and notes the advantages of its SDR architecture for future updates. He describes the straightforward setup process, from unboxing and connecting PowerPole connectors to making a first contact with N0HQ, a special event station. N2LRB expresses satisfaction with the radio's clear audio and ease of tuning, even if the pan-adapter's utility for his operating style remains to be fully explored. He concludes that the IC-7300 offers exceptional value, providing SDR features and receive performance comparable to more expensive rigs at half the cost.

specialize in trading Russian vacuum tubes used in broadcasting, amateur radio, Hi-Fi audio, meteorology, communication, medical applications and industr

First released around 1995 and significantly redesigned as QWTelnet 2, this software provides a dedicated interface for monitoring DX-Cluster traffic via Telnet. It integrates a **SOTAwatch parser** with configurable audio alerts, allowing operators to receive notifications for specific search patterns in DX-Cluster remarks without constant screen attention. The application also supports parsing for **GMAwatch (German Mountain Award)**, providing alerts for German Mountain Award activations. QWTelnet 2.4.0, released on 07-APR-2012, runs on Windows (tested on W7) and is distributed as a ZIP file containing the `qwtelnet.exe` executable. It does not require a formal installation process; users simply extract and run the program. The software can display DX information for single bands, integrate with the Reverse Beacon Network, and link to external web resources for DXCC and SOTA information. It also supports local reference files for IOTA, WFF, and RDA awards, which users must source and place in the `qwtelnet/files` directory. For IOTA data, users can convert `IOTA.CSV` from UCX-Log or `DX4WIN_IOTA.TXT` into `iota.csv`. WFF and RDA reference files are directly sourced from their respective websites.

The Icom IC-7300 is a groundbreaking Software Defined Radio (SDR) transceiver that revolutionizes the way amateur radio operators interact with the spectrum. With its large 4.3-inch color TFT LCD touch screen, users can easily navigate through various functions, including real-time spectrum scope and high-resolution waterfall displays. This allows for quick adjustments and enhanced signal awareness, making it easier to find and engage in QSOs. The touch screen interface provides a modern approach to radio operation, replacing traditional buttons with virtual controls that can be accessed with a simple touch. In addition to its user-friendly interface, the IC-7300 boasts advanced features such as IF-DSP filtering, audio scope functions, and a multi-dial knob that combines tactile control with touch screen flexibility. These capabilities enable operators to visualize signals and make precise adjustments to their settings, ensuring optimal performance during contests or casual operating. The IC-7300 is designed for both beginners and experienced hams, making it a versatile addition to any shack. Its innovative design and functionality truly embody the spirit of modern amateur radio.

Vintage Tube Radio's from Germany for sale. High class restorations for all valve radios offered. Radio Brands like Saba, NordMende, Majestic, Grundig, Zenith, Philco and more. TubeRadioDoc Vintage Audio Store

Manufactures automatic mixers, analog and DSP signal processors, room combining and matrix mixers, and audio test equipment for just about any customer application.

Demonstrates the fundamental principles for connecting a personal computer to a ham radio transceiver, specifically for utilizing sound card-based digital mode software like those in the MM Hamsoft suite. It details the basic hardware setup, emphasizing the use of shielded leads and proper audio routing from the radio's output to the sound card's input, and from the sound card's output to the radio's microphone or data input. The resource highlights the critical need for transmit attenuation, suggesting a 100:1 voltage divider to prevent overdriving the transmitter's audio stage, and mentions the optional addition of ferrite beads and decoupling capacitors for RFI mitigation. The guide also points to external resources for more detailed pin-outs and interface schematics, such as a specific QSL.net page, and recommends consulting the help files within MM Hamsoft programs for interfacing specifics. It underscores that while the process is straightforward, understanding the audio level management and proper cabling is key to successful operation. The author, VE5KC, provides practical advice drawn from common issues encountered by operators setting up digital mode stations.

A CW sidetone bypass for the NESCAF audio filter, a small and low cost circuit that works great.

The New England QRP NESCAF Kit Switched Capacitor Audio Filter by N5ESE

In his page the author includes 27 mp3 audio files that compose the whole CW training course, instructions and whole lessons transcript are available in Italian and English.

An overview of digital HF radio operating modes includes a sample audio recording of each digital mode by WB8NUT

Live Audio Feed of the KI4FVI repeater in henry county Georgia

Program for the control of the transceiver from your PC. Works on windows and has been tested with different serial and USB interfaces, Based on hamlib libraries , Auto CQ for repetitive calls, Audio Recorder, BktNetInterface for JTDX and WSJT-X

TS-850 is not much effective on AM since it does produce fairly clean audio, however while it does noticeably improve low-end frequency response

LA6EIA Ole's DX-blog details shortwave listening (SWL) and amateur radio DX operations from Norway, providing insights into propagation conditions and station reception. The blog frequently features specific reception reports, often including details such as frequency, mode, and signal strength, alongside observations of various broadcast and utility stations. It documents the author's personal experiences in chasing DX, offering a practical perspective on radio propagation and equipment performance. The content includes logs of received stations, sometimes accompanied by audio clips or screenshots of waterfall displays, illustrating successful decodes or strong signal captures. This resource presents a chronological record of DX achievements and challenges, reflecting the dynamic nature of radio propagation across different bands and times. The blog distinguishes itself by its focus on real-world SWL and amateur radio DXing from a Nordic QTH, offering a unique regional perspective on global radio phenomena. It serves as a personal journal of radio exploration, highlighting specific callsigns, frequencies, and operational details encountered during DX sessions.

Amateur radio repeaters extend communication range for mobile and remote stations by retransmitting signals on a different frequency, often for emergency communications. The resource details various repeater bands, noting that 2 meters and 70 cm are primary for activity, with 10-meter repeaters offering potential national and overseas coverage. It specifies **18 channels** on 6 meters and **31 channels** on 2 meters, along with a new 70 cm offset of _7 MHz_ adopted in 2015. The content explains how repeaters can be linked via dedicated transmitters/receivers, landlines, or Internet VoIP systems like _IRLP_ and Echolink, enabling global connections. It also describes simplex gateways for multi-band operation and the use of CTCSS subaudible tones for access control and interference mitigation. The document highlights specialized repeaters for modes beyond voice, such as SSTV and ATV, particularly on 70cm and higher bands. Operational guidelines for efficient and courteous repeater use are referenced, along with links to Australian repeater listings and band plans.

Contest audio recording for N1MM. external "plug-in" which adds a QSO audio recording function.

Ham Supply continue to manufacturer the fine Idiom Press electronic keyer, audio filter and other Ham Radio related products

When assembling a robust shack, the quality of interconnects often determines overall system integrity and signal fidelity. Neutrik, with over 50 years in the connectivity sector, specializes in professional-grade connectors that withstand rigorous use in entertainment and industrial applications. Their product range includes XLR, speakON, powerCON, and opticalCON series, which are frequently adapted by hams for critical station infrastructure, particularly in contesting or DXpedition environments where reliability is paramount. Amateur radio operators often repurpose these durable connectors for antenna switching matrices, audio interfaces for digital modes, or power distribution systems. The robust locking mechanisms and high-quality contact materials found in Neutrik products ensure stable connections, minimizing intermittent faults that can plague field operations or even fixed station setups. This attention to mechanical and electrical integrity aligns well with the demands of high-power RF environments and sensitive receive chains. While primarily serving the pro-audio and video markets, the engineering principles behind Neutrik's designs translate directly to the needs of radio amateurs seeking superior performance and longevity from their cabling and connection points. Their commitment to innovation, as highlighted by their 50-year journey, suggests a continuous evolution of products that could benefit future amateur radio applications.

Next Generation Beacon hardware platform encompasses both analog and digital modes, i.e. CW FSK and MGM in a mixed mode configuration. The advantage of the mixed mode is that humans can decode the CW FSK by ear and the MGM can be decoded by computers way below what is audible. Therefore the MGM can be used for pre-human-conditions or early warning monitoring.

Circuit designs for IC audio amplifiers by N1HFX

Windows free sound recorder. What you save is what you hear ! Small utility program to capture and save any sound played by your computer. Audio recorded can be converted in MP3 format.

A guide to properly use FT8 ALC and power when transmitting in FT8 Mode. Incorrect usage of power and audio from your computer may cause unreadable signals and transmit harmonics that can didturb other signals.

Operating where independent media is suppressed, _Radio Free Europe/Radio Liberty_ (RFE/RL) delivers news and information in 27 languages to audiences in 23 countries. This resource primarily functions as a news portal, focusing on geopolitical events, regional conflicts, and human rights issues, particularly in areas like Ukraine, Russia, Iran, Afghanistan, and Central Asia. It features articles, videos, podcasts, and photo galleries, covering topics such as international relations, energy politics, and the impact of conflict on civilian populations, often highlighting the perspectives of local journalists and freelancers in challenging environments. The content frequently addresses the operational context of shortwave broadcasting, though the site itself is a digital news platform. For example, it details the implications of long-distance strikes and regional military capabilities, which are relevant to understanding the strategic importance of various communication methods. The resource also provides insights into the challenges faced by populations in areas with limited access to uncensored information, underscoring the role of independent news organizations in providing alternative narratives.

This page describes some of the settings needed to properly connect the USB port to handle audio and PTT

The Ultimate Control Software for the IC-7300, IC-7610, IC-7600, IC-7850, IC-7851 and Others is a control software suite that includes additional interesting features such as support for the built in Spectrum Scope, Audio monitors, Shortwave DB, CW Terminal, Clublog Spotting, Memory management, interface to Ham Radio Deluxe Logbook, DM780, n1mm+, log4om, DXLab and other. Runs on Windows OS, commercial licence.

Mic online calculator , Microphone Dynamic Range Calculator, Microphone Sensitivity Calculator