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Projects you can build, an amplified shaped sine-wave oscillator

Details the construction of an **HF converter** designed by M1GEO, George Smart, specifically to extend the frequency range of the FunCube Dongle Pro (FCD) for amateur radio reception. The FCD natively covers 64 to 1,700 MHz, but this project enables reception from 0 Hz to 64 MHz by up-converting signals to the FCD's operational range. It employs a **double-balanced mixer** with a 100 MHz local oscillator (LO) to translate incoming HF signals; for instance, a 1 MHz signal appears at 101 MHz within the FCD's passband. The design incorporates a 7th-order Chebyshev low-pass filter with a 62 MHz cutoff frequency at the input to mitigate image frequencies, ensuring cleaner spectral presentation. George provides the schematic, PCB masks, and Gerber files for replication, noting that Far Circuits also offers PCBs. The resource includes test results for the low-pass filter and measurements of LO leakage, identifying -36.8 dBm at 100 MHz as a potential sensitivity concern. M1GEO discusses potential improvements, such as adjusting the mixer's LO drive, adding a balance pot, or incorporating a post-mixer high-pass filter to reduce LO breakthrough. Audio recordings from 40m and 17m demonstrate the converter's performance with WRplus SDR software.

A simple free running oscillator oscillating at the receiver\'s IF (intermediate frequency) beats with the incoming signals in either CW or SSB and the resultant audio frequency goes to the AF amplifier.

A 109 pages presentation in PDF File by Jim Brown K9YC on techniques in operatint the top band from a small lot.

PL-259, Motorola & N connectors, Coax Seal, universal adapter kit, TNC, Mini-UHF, SMA, F & BNC connectors, audio connectors,antenna mounts and antennas

Provides broadcast times, frequencies and power of the network emissions. Airs mediumwave, FM, shortwave and RealAudio broadcasts

Sonogram is a highly flexible audio spectrum analyzer for the analysis of sound, music and speech signals in the frequency-domain using different algorithms.

Home build a Kenwood PG-5A cable. This lead is the audio data cable for some of the Kenwood Mobile transceivers

A resource for Collectors and Restorers of Vintage Electronic Equipment.

Online in RealAudio and Windows Media formats, with multiple language shortwave schedules, and instructions for receiving Australian satellite radio and TV (AusTV).

An illustrated modification for the Icom IC-R20 receiver to locate and use the unfiltered audio.

Worldwide sellers of vacuum tubes and electron tubes for audio, radio, and industry

West St. Louis County Police and Fire Live Audio Feed

Audio Repeater is a windows application tha allows you to transfer, transmit, sounds from an input audio endpoint or device to an output one Playback. Audio transfer can be performed in any PCM audio format supported by Windows. KS version communicates directly with audio driver, bypassing all additional Windows audio processing

Designed to handle audio signal interfacing as well as transmit/receive switching Reviewed by Steve Ford, WB8IM

Audio setup at N2RIT built around the Yaesu FT-950 abd the Heil Sound PR-781 an ultraflex PRO EX3200

Design Guidelines for JFET Audio Preamplifier Circuits By Mike Martell N1HFX

Modification leaves nearly all of the existing Omni agc circuitry intact, simply add an audio detector which modifies the delay characteristics of the original system by G3IXQ

The page provides circuit improvements for the Kenwood TS-440S transceiver, addressing issues such as distortion in SSB signals, limited transmit frequency coverage, lack of crispness in RX audio, and flat audio response. The fixes include adjusting bias, cutting specific components, and changing capacitors to improve performance.

Current program schedules, RealAudio feeds, and listening tips from Belgian Public Radio which broadcasts worldwide in Dutch, German, French and English.

About SSB Audio by N4KC

Amateur radio repeater scanner at Pomona California

The document explains the technical aspects of how the Internet Radio Linking Project (IRLP) works, focusing on the use of VoIP streaming software under the Linux operating system. It details the audio sampling, compression, transmission, reception, and playback processes involved in IRLP communication.

MiniDSP is a platform for digital audio signal processing applications. Manufacture low cost digital signal processor kits for the DIY/OEM market. Our flexible audio platforms are software controlled and easily upgradeable.

A forum post at WZ5Q with modifications of Kenwood TS-2000 audio fratures

LEMO, established in 1946, specializes in high-performance interconnect solutions, offering an extensive range of over 50,000 circular connectors. Their product line includes the REDEL SP IP68 series, which features resin-free IP68 sealing for robust performance without complex potting processes. These connectors are critical for applications in medical, military, test and measurement, security, defense, and industrial sectors, ensuring reliable signal integrity in harsh conditions. The company designs, tests, and manufactures high-quality cable solutions, providing complete connectivity services such as custom cable assembly and signal integrity analysis. LEMO's solutions are integral to advanced scientific endeavors, as demonstrated by their use in CERN’s NA62 experiment for instrumentation and maintenance. LEMO's 80-year history, detailed in their anniversary publication, highlights their evolution from a Swiss family workshop to a global leader in connector technology. Their product finder tool assists customers in selecting appropriate connectors from their broad portfolio, which also serves audio-video, transportation, aerospace, and UAV applications.

Elecraft KX2 tips and tweaks about how to improve your receive audio on the Elecraft transceiver

Fixing notice subtle distortion on SSB receive audio on the Yaesu FT-1000D

Council Bluffs area Sheriff, Police, Fire, and State Police IOWA

Build this noise reducing system to enhance audio of your speaker. A project by kg4jjh

A collection of audio amplifier projects by N1HFX

This online project guide details the construction of a homebrew boom microphone system. It details the assembly of a microphone shell from a 3/4" PVC pipe section and an end cap, requiring a drilled hole for a snug fit of the electret or condenser mic element. The internal wiring schematic specifies a **2.2 K** resistor and a **47 uF** polar capacitor for signal conditioning, with a circuit diagram provided for integration with IC-706 series transceivers. The guide outlines the use of CAT-5 cable for internal connections, incorporating strain relief at the rear of the mic shell, and an inline 3.5 mm jack to facilitate an external _PTT_ line, designed for a foot-mounted switch. Further construction involves fabricating a microphone shock mount from a 2-inch PVC connector, detailing the creation of four "fingers" and the insertion of screw-eyes for attaching elastic bands, which are twisted 180 degrees for tensioning and vibration isolation. A foam wind screen is also incorporated into the microphone assembly, secured with adhesive. The boom arm itself is repurposed from an articulated architect lamp, with the original lamp assembly converted into a **60 watt** resistive load for testing power sources. Microphone cabling is secured to the boom arm using wire ties, ensuring sufficient slack at hinge points to maintain articulation. The boom base is mounted to a bookshelf, requiring specific positioning to achieve proper microphone placement in front of the operator. Performance evaluation of the microphone system is conducted through on-air audio signal reports from other amateur radio operators. DXZone Focus: Online Project Guide | Boom Microphone Construction | Electret Mic Element | PTT Line

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

A selection of speakers or headphones for use with amateur radio equipment. Includes an interesting paragraph comparing Dynamic and Electret Condenser Microphones, but also about audio Equalization.

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

Manufacturer of professional audio test and analysis equipment and of cb, marine and amateur radio accessory equipment.

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

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.

collection of vintage audio equipment

Review of common audio speakers for mobile setups

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.

The eSSB Audio Page at K6HP web site

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

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

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.

Demonstrates the capabilities of CW_Shark, a dedicated 32-bit Windows application for Morse code operations. This software facilitates the analysis, decoding, and encoding of CW signals, providing hams with a versatile tool for various aspects of amateur radio communication. It supports four distinct modes: Decode Only, Keyboard QSO, Straight or Paddle Key QSO, and Straight or Paddle Key Practice, catering to different user needs from passive listening to active keying. Operators can utilize the Decode Only mode for signal analysis, while the Keyboard QSO mode allows for text-based interaction. The Straight or Paddle Key QSO mode offers a direct interface for traditional keying, enabling real-time communication. For skill development, the Straight or Paddle Key Practice mode provides a structured environment to hone Morse code proficiency. CW_Shark integrates essential functions for CW enthusiasts, supporting both learning and active participation in Morse code exchanges. Its focused design aims to assist operators in mastering and enjoying the art of _CW communication_.

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