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Audio Spectrum Analyser Spectrum Lab or Speclab started as a simple FFT program running under DOS a long time ago, but it is now a specialized audio analyzer, filter, frequency converter, hum filter, data logger and more. Can be used for MTHELL QRSS, DFCW, PSK, MSK, Castle. Spectrum Lab is a free audio analysis tool, lets you see the hidden world of sound. It analyzes live audio or recordings, showing you the exact frequencies present. Watch sounds change over time with a waterfall display. Need to clean up your audio? It can filter out noise in real-time. Even play with radio signals by decoding and creating special modes! While ideal for amateur radio enthusiasts, anyone can explore the science of sound for free.

MFJ manufacturer of ham radio antenna products, antenna tuners, antenna analyzers, morse code & CW, SWR wattmeters, antenna accessories , power supplies, audio filters, TVI filters, baluns, coax switches and more

Free programmable LOW/HIGH/BANDPASS FIR filter in the audio range 0-4kHz

HamCalc is a free collection of calculators for radio amateurs include Antenna ERP calculations, Attenuators, Audio Filter design, Coil Winding, Decibels, Great Circles map and calculator, HF Filters, HF Traps, Metric conversions OP Amps QRA Locator to Latitude/Longitude, Radio Horizon calculator, Resonance Satellite orbit calculator Timer calculations (555 timer)Zener Diode calculations Download zip By G4VWL

A freeware program to dig out weak signals buried in noise, functionally similar to the excellent FFTDSP of AF9Y, but with the added bonus of real time audio filtering of the incoming signals. Just point and click with the mouse, and the selected signal will stand out from the QRM and noise.

Program designed to do spectral analysis and real-time audio filtering on reception of audio signals for EME, VLF, SETI applications. Offer support for MTHELL, QRSS, DFCW, NDB, WSJT by I2PHD

Sells leading-edge voice and digital communications products to the world-wide military, government, industrial, and amateur radio marketplaces. Bluetooth Remote Audio/PTT, Rig Controller with Audio & PTT , HamLinkUSB Rig Control, Noise filtersm antenna analyzers, Multimode Data Controller, TNC, Packet Radio Terminal Node Controller. USB2RS232

CW keyers, Logikey, and antenna rotator controll like rotor-ez, and active audio low pass filters.

A re-usable control & computing platform for antenna measurement, PSK31 digital modems, audio filtering, signal source & VFO, memory keyer by AMQRP

This circuit consists of microphone amplifier and a high pass filter. Suitable to improve signal readability.

Maker of QRP Kits, QRP CW receiver and transmitters, audio CW Filters, antenna tuners, dummy loads, and morse code practice oscillator

Sherwood Engineering Inc., based in Denver, Colorado, specializes in ham radio accessories and components. The company, located at 1268 South Ogden Street, offers a variety of products including filters, cooling kits, and audio switch boxes. Sherwood Engineering is known for its work with brands such as _Drake_, _Icom_, and Collins, providing components like 455 kHz mechanical and crystal filters. The company has also been involved in producing first-IF roofing filters and DSP protection filters. Sherwood Engineering has a history of over 45 years in the industry, though it has now retired from producing certain products like the SE-3 MK IV. Despite this, the company continues to provide technical resources and presentations on optimizing rig performance, with past events held at venues like the Dayton Contest University in 2014. The company operates Monday through Friday, from 9 a.m. to 5 p.m. Mountain Time, and accepts payments via PayPal, check, or money order. DXZone Focus: Denver | Filters | Icom

Taking the venerable SMK-1 design to 20m and adding an RF amp, audio filter, and a TiCK Keyer ... by Wayne McFee, NB6M

The direct conversion receiver described consists of only a bandpass filter, mixer IC, VFO and audio filter. With only 22 parts, this simple circuit should take a few hours at the weekend to construct.

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

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.

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

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

NEScaf: A Switched Capacitive Audio Filter

This article shows how to make a mains filter that can be extremely effective in reducing and in some cases eliminating completely EMC from the electricity supplying your shack

Start by getting your audio levels sorted out, Having your levels correct is critical to maximum effectiveness in both TX quality and also for being able to decode signals properly. Guide to Filters and other Rig Settings to optimize your output signal

An home madek Audio CW Filter made simply using SMD Components

Pro Audio Engineering (PAE) supplies products for broadcast and amateur radio applications. The company manufactures heatsinks for _Elecraft_ **KX2** and **KX3** transceivers. PAE also produces AC power supplies for HF transceivers, remote power relays, and Ethernet relays. Machined products from PAE are manufactured in the **USA**. PAE distributes _Fair-Rite_ Mix 31 ferrite snap-it cores and toroid cores in various internal diameters. The product inventory includes commercial monitoring antennas, UQUI transformers, ULP AC power filters, and 3M conductive adhesive copper tape. Offerings also include the AM1 Portable Antenna Mount System. Pro Audio Group, LLC holds the copyright for the company as of 2024 DXZone Focus: _Elecraft_ | _Fair-Rite_ | Heatsinks | Ferrite Cores

Adding 2 RCA inputs, 1 high impedance filtered audio output RCA 3, 3 HIGH PASS filters, 3 LOW PAS filters to the JRC NVA88 Speaker

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.

Andrew Roos (ZS6AA) details his practical approach to building a Single Operator Two Radio contest station within suburban constraints. The article explains how he leveraged a Force-12 C-31XR triband beam's unique separate feed arrangement to operate on two bands simultaneously. Using band-pass filters and an antenna switch, he achieved sufficient isolation between bands without requiring multiple towers. The setup includes automatic band selection, audio switching, and computer control. Testing during the 2007 CQ WPX CW contest confirmed the system's effectiveness, demonstrating that competitive SO2R operation is achievable with limited space and budget.

The page provides details on an improved filter for the TS440 CF2 slot with better selectivity and shape factor than stock versions. It includes information on LTSpice Analysis, essential changes to capacitors, and suggestions for optimizing audio bandwidth for AM phone use. The content is geared towards hams or amateur radio operators looking to enhance their TS440 transceiver performance with filter upgrades and capacitor adjustments.