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Online Constant - k Lowpass Filter calculator

Butterworth Highpass Filter Designer

A summary, overview or tutorial covering the basics of Meteor Scatter or Meteor Burst Communications, a form of radio signal propagation often used at VHF.

Near Vertical Incidence Skywave propagation is a form of radio wave propagation used on the MF and HF bands to provide radio communications and broadcasting coverage over short distances, especially where the terrain contains obstacles.

The basics of radio receiver dynamic range performance used for specifying the performance of radio receivers used in radio communications systems.

An overview of the development of the Morse key for sending the Morse Code, from the first camelback keys, through straight keys and sideswiper keys to the semi automatic keyers including the Vibroplex to the modern electronic keyer.

HF converter for SDR radios

Article on antenna feed impedance and the importance of matching RF andtennas to feeders, including notes on Radiation resistance, loss resistance, and efficiency are also detailed.

Constructing a high-performance RF spectrum analyzer up to 1000 MHz requires careful attention to component selection, shielding, and circuit isolation. This resource details a project that improves upon the _Spectrum Analyzer for the Radio Amateur_ design by Wes Hayward (W7ZOI) and Terry White (K7TAU), incorporating ideas from Scotty Sprowls' project, particularly his 1013.3 MHz IF bandpass cavity filter. The analyzer utilizes a Mini-Circuits SRA-11 mixer with a sweeping local oscillator from 1013 to 2013 MHz, feeding into a 4-pole copper pipe cavity filter. The design employs a second SRA-11 mixer with a fixed 1024 MHz LO to produce a 10.7 MHz final IF. This signal then passes through narrowband resolution filters and is processed by Analog Devices AD603 and AD8307 ICs for IF amplification and logarithmic detection, driving an oscilloscope in X/Y mode. The project emphasizes modular construction, using salvaged components and double-sided FR4 material for PCBs, with critical notes on minimizing spurious images through effective shielding and proper voltage regulation for each module. Key components include a Z-Communications V585ME48 VCO for the first LO and a Z-Comm V583ME01 VCO controlled by a Motorola MC145151 PLL for the second LO. An optional Hittite HMC307 step attenuator and K&L 5L121-1000/T5000-O/O low-pass filter manage RF input. Tuning procedures for the 10.7 MHz IF resolution filter are also detailed, showing before-and-after spectrum views.

About antenna or aerial resonance and bandwidth and the impact of RF antenna resonance and bandwidth on radio communications systems.

Brugtgrej presents a Danish online classifieds platform specifically for amateur radio operators and electronics enthusiasts. The platform facilitates the buying and selling of used equipment, including transceivers like the Icom IC-7410, various components such as X'TAL FILTER FMT-15A and TRANSISTOR 2SC3019, and accessories like Sadelta microphone capsules and SMA to SMA extenders. Users can post free advertisements for items they wish to sell or acquire, covering categories beyond amateur radio, including antique radios, military radios, and radio tubes. The site lists active advertisements, with 3136 online ads and 167 online users at the time of analysis, indicating a dynamic marketplace. It also features a forum for community interaction, discussing topics like repeater rings on 1297 MHz and FT8 activity. The platform's structure supports both 'Sælges' (for sale) and 'Købes' (wanted) listings across its various sections. Specific items observed include a Miniwatt pentode 4689, various capacitors and coils, and general electronic components, demonstrating the breadth of offerings available to the amateur radio community.

Permo electronics amateur radio dealer for ICOM YAESU and KENWOOD in Norway

Tabor electronics produces high-end function generator, universal counters/timers, synthesizers, pulse, function and arbitrary waveform. Frequency counters

Kevtronics is an ham radio shop online, sell Yaesu, Icom and Kenwood radios, LDG electronics products located in South Africa

This resource is an online tutorial focused on setting up the Raspberry Pi for amateur radio applications. It covers the installation and configuration of various software packages tailored for digital communications and protocols, including _Packet Radio_ with Hamlib and Direwolf, as well as data modes like FLDigi and WSJT-X. The guide also details the integration of hardware components such as GPS clocks for time synchronization and real-time clocks for enhanced functionality. Users will find instructions for installing software like GPredict for satellite tracking and GQRX for software-defined radio (SDR) applications. The tutorial emphasizes practical steps, including the use of command-line inputs in the Raspberry Pi OS terminal, and provides troubleshooting tips for common issues such as faulty SD cards or insufficient power supplies. Operators are encouraged to explore various applications, including APRS iGates and WSPR beacons, to enhance their ham radio experience. The material is designed for licensed amateur radio operators with basic knowledge of electronics and computing.

A linear regulated power supply 2A, 20 V designed mainly to get used to soldering and have something usefull as final result.

The details of the spark gap transmitter and its history: how it was invented, developed and used.

Cmpter Electronics specializes in the design and manufacturing of RF coaxial connectors, RF adapters, and RF cable assemblies, serving diverse applications across datacom/telecom, automotive, instrumentation, aerospace, and defense sectors. Their product line includes RF coaxial terminations, attenuators, and waveguide to coax adapters, catering to specific needs in radio frequency systems. The company also offers precision adapters and connectors, alongside glass beads and test cable assemblies, indicating a focus on high-quality components for demanding RF environments. Their resource center provides valuable information, including an "RF Made Simple" section and a product catalog for download, which assists engineers and technicians in selecting appropriate components. The product named system helps in identifying specific parts, streamlining the procurement process for complex RF solutions. With a comprehensive range of RF coaxial cables and related tools, Cmpter Electronics positions itself as a key supplier for critical infrastructure requiring reliable signal integrity. Their offerings support a broad spectrum of RF applications, from basic connectivity to advanced test setups.

Electronics surplus outlet in Redondo Beach, CA

Article on propagation basics. The ground wave used for radio communications signal propagation on the long, and medium wave bands for local radio communications

The _Touch CPO_ circuit offers a unique method for Morse Code practice, eliminating the need for a physical key. It leverages the versatile IC555 timer, configured as an astable multivibrator, to generate an audio tone. Users can adjust the tone's frequency by manipulating a 100 K variable resistor connected between pins 7 and 6 of the IC555, providing flexibility in the practice experience. Volume control is achieved via a 10 K variable resistor, while a 1 K Ohms preset at pin 4 of the IC555 allows for fine-tuning the touch plate's sensitivity. The design connects the touch plate to the base of a BC147B transistor, a configuration noted for its flexibility regarding the length of wire between the transistor and the touch plate. The author's prototype successfully used a 9 cm wire with a 3 x 6 cm aluminum plate. This project also suggests an alternative application as a touch-operated doorbell, demonstrating the circuit's adaptability. The design emphasizes simplicity and ease of construction, making it accessible for hams interested in DIY electronics.

All the essentials about the Dip Meter or Grid Dip Oscillator used for many RF measurements including detecting resonance, locating RF emissions, and making many RF measurements.

overview of radio signals and radiowave propagation and how different areas of the atmosphere affect radio communications.

Descriptions, summaries,and tutorials about electronic circuits and electronic circuit design including amplifiers, attenuators, logic, transistor, operational amplifiers and much more

Electronics components, rf connectors worldwide dealer

VU2.IN Amateur Radio, HAM Radio India. Amateur radio portal from India, about emergency communication, disaster management, electronics, HF and VHF Radio hobby

Article on how to use logic analyzers for testing complex logic-digital circuits

Introduction to troposcatter or tropospheric scatter propagation using the troposphere

Haredata Electronics is your one stop shop for Power Supplies, Chargers, Battery Packs & Accessories. Power Supplies Chargers, Battery Packs , Power Supply Accessories , Haredata Electronics Limited,

Midwinter Madness Hamfest, hobby electronics show. Buffalo Civic Center. VE exams. Talk-in 147.000

AmTOR may be considered as the next development from RTTY. AmTOR was introduced to overcome the problems with RTTY. As a result of its performance, it has become popular on the HF bands because it gives more reliable communication, especially when interference is present. It achieves this by using a coding system that allows errors to be detected and corrected.

The original SurplusEQ.com domain, once a hub for amateur radio operators and electronics enthusiasts seeking test equipment, meters, and various high-tech components, has been repurposed. Historically, such platforms facilitated the acquisition of essential gear for shack setups, antenna analysis, and general electronics work, often providing cost-effective alternatives to new retail purchases. The site's previous focus on "test equipment, meters, testers" directly supported the technical aspects of the hobby, from RF measurements to circuit diagnostics. Currently, the domain points to a gambling platform named "SEMUTWIN," offering online slot games, live casino options, and other digital wagering activities. This shift represents a complete departure from its former identity as a resource for surplus electronics and amateur radio-related equipment. The content now features game titles like "Sweet Bonanza Super Scatter" and "Gates of Olympus Super Scatter," alongside promotional offers for online gaming.

An introduction to develpment of morse keys in radiotelegraphy history

Attenuators, Couplers, Power Dividers, Terminations

Makers of the worlds smallest automatic solid state HF amplifier Expert 1K-FA, Expert 2K-FA and Expert 1.3K-FA

Online HB9CV antenna calculator, accept as input the desired resonating frequency and provides dimensions for spacing and length of each element, including boom and radiator diameter.

Hinckley, Leicestershire ham radio club

An overview about the UHF connectors often referred to as the PL259 plug and SO239 socket used for many RF applications. Limitations, history and soldering properly UHF Connectors

Delta Electronics Manufacturing, a global manufacturer, specializes in _RF connectors_, adapters, and cable assemblies, providing custom interconnect solutions with superior performance. Their Advanced Vertically Integrated (AVI) global facilities emphasize efficiency, quality, flexibility, and cost control across their product lines. The company serves diverse industries, including broadcast and audio, test and measurement, military, aerospace, and public safety communications. For instance, Delta supplies RF interfaces for military aircraft, satellite launch vehicles, and missiles, maintaining a long-standing QPL supplier status. Their field-tested RF interconnects are also crucial for two-way radios, base station equipment, and antenna systems in public safety applications, ensuring reliable performance in critical communication infrastructure. Delta's solutions extend to commercial aircraft and semiconductor manufacturing, where their RF interconnects power etch equipment, deposition equipment, and chip testing systems worldwide.

The premier flea market for radio, electronics, Computer & communications equipment in Indianapolis

+/- 15 V, 1.5 A power supply project

Article descrive the different types including coax and open-wire feeder and waveguide.

Delta Electronics, Inc. NY USA, family owned and operated selling all varieties of consumer electronics including 10 meter amateur radios, antennas, accessories, microphones, cw transmitters, coax cables and more

Key details about the superhet or superheterodyne radio reeiver: basic overview; how it works; applications; design notes, all you need to know.

Stocking store for electronics components,obsolete parts. Professional IC supplier. Stocking store for electroncis components & IC's,obsolete parts.

Ham radio and electronics radio blog from India

Station QRP presents various **circuit diagrams** for constructing low-power AM vacuum tube shortwave transmitters, catering to enthusiasts interested in vintage radio technology. The resource details schematics ranging from simple to more complex designs, enabling hams to build their own QRP AM transmitters for operation on frequencies like 6.925 kHz AM. It emphasizes the use of vacuum tubes, providing a technical foundation for understanding and replicating classic shortwave broadcasting methods. The content is geared towards those who enjoy the hands-on aspect of electronics and the unique characteristics of tube-based RF circuits. Building these transmitters allows operators to experience the nostalgia of early shortwave radio, with the site specifically mentioning a pioneer station on 6.925 kHz AM. The designs facilitate experimentation with low-power AM transmission, offering practical application for homebrew projects. The focus on QRP (low power) operation aligns with a segment of the amateur radio community that values efficiency and minimalist setups, providing a distinct alternative to modern solid-state transceivers.

an overview, introduction or tutorial about the basics of electronics filters including the types of filter and the various filter design considerations and parameters

Article about tropospheric propagation and the way in which radio signals at VHF and above propagate over greater distances than strictly line of sight in the troposphere

Amateur radio accessories, like the CT-17B ICOM CI-V hubs, IABs ICOM ACC1 Breakout boxes, GS232Dunio GS232A/B arduino based rotor controler, IMK memory keypad for ICOM Radios