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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

This circuit is very simple and has a fantastic range of potential uses.

The VersaBeacon is a frequency agile, modulation agile RF source using a DDS chip and minimal support circuitry. It covers a frequency span of 1MHz to 150MHz in 1 Hz steps and provides a variety of modulations

This RF probe circuit allows RF to be measured in the presence of DC

An easy to build and extremely high performance antenna, works perfectly on all HF bands 3.5-28 MHz with some compromises, it is basically an half wave dipole for 40-80 meters, an LC circuit or trap 40 meters allows you to use a single radiating element.

RF/Microwave Simulator for Puppy Linux by WN2A

While intended mainly for antenna loading coils, this article also applies to other resonant systems, such as amplifier tank circuits.

Build you own RF probe, measure the level of RF voltage present at a particular point.

A browser based circuit simulator offering a large set of functionalities allowing to share and discuss designs

DesignSpark PCB is the world's most accessible electronics design software, specially designed for Rapid Prototyping and turning your circuit ideas into testable boards faster. Easy to learn and easy to use, DesignSpark PCB is free and can you can download DesignSpark from this site.

Some test circuits using the ACE-HF System Simulation & Visualization software, about reciprocal propagation on HF bands by NW7US

The MC3423 can protect sensitive circuity from power supply transients or regulator failure when used with an external "Crowbar" SCR.

EasyEDA - Web-Based EDA, schematic capture, spice circuit simulation and PCB layout Online.

The program can be used to calculate inductors (coils) and their number of turns on ferrite cores, ferrite shells and air coils. These can be used for baluns, Ununs, bandpass filters, low pass filters, resonant circuits, and more. The technical specifications of the cores are already integrated in the program. Application is free and runs on Windows 32 bit versions only. To make it run on Windows 10 64 bit need to be unzipped in a single folder.

The dip oscillator is a useful piece of test equipment for the radio amateur. Circuit by VK3YE

Article describes a circuit that accelerates the coil of DC relays by momentarily doubling their voltage.

Antenna design for Horn Antennas

Noise Canceller kit originally developed about 1989 by G4WMX and GW3DIX and improved by DK9NL and DG0KW.The VK5TM Noise Canceller is another version of the design, with the HF Vox circuit removed and a couple of other minor changes, including the use of SMD JFETs and a double-sided pcb.

An home made low noise preamplifier project for 144 MHz, with detailed circuit diagram. The VLNA-144 preamplifier has been Published on DUBUS 4 2019

Vacuum Tubes History, Theory, and Circuits

An economical way of building an SSB filter. The circuit is for a filter with a 6 DB band width of roughly 2.2 KHz.

A 600 volts power supply for QRO

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

Little circuit of a Morse Code Oscillator is presented here. Excellent for learning and teaching Morse code

Baofeng UV-5R uses RS232 to communicate or programming with the PC software and you can make your own programming cable with a few components.

Cavity filters are tipically circuitry behind a duplexer that allow only certain frequencies to pass

IdealCircuit is an analog circuit simulator working with true ideal components. It uses exactly the same unique and robust algorithm as NL5 Circuit Simulator. Simple and intuitive interface, fewer components and models, no fancy and powerful features that are only useful for specialized applications.

RF / IF Microwave components DC to 20 GHz

Details on projects by WA3TFS published in QST magazine over the past few years. Includes an online shop with several ham radio kits, circuit boards, simple SDR transceivers

This antenna is an omnidirectional and multiband and it is well suited for DX enthusiasts with limited space. Each of the parallel circuits (trap) behaves like an isolator on its resonant frequency.

Circuit designs for IC audio amplifiers by N1HFX

AFR Enterprises a leading distributor of electronic components, semicondustors, diodes, Resistors, Integrated Circuits across the USA.

A simple CPO for those who want to practice CW in a different way, with out the morse key

An improved version of the audio interface commonly used to connect a computer soundcard to a transceiver\'s receive and transmit audio circuits

Printed circuit board design for Macintosh

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

Basic electronic circuit laws, capacitors, resistors, power circuits examples

This circuit stores a morse code message as bits in an EPROM chip, the message controls a relay that keys a CW morse code transmitter. An Arduino processor can also be used in place of this circuit, that eliminates the need to build the circuit and program an EPROM.

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

Tuned circuits for Progressive Receivers

Noise bridge circuit to tune your tuner

Microprocessor based interface designed receives a signal from a Morse key, processes it, and re-transmits it to the radio. A microprocessor in the circuit is pre-programmed with a proprietary algorithm which makes a number of measurements and adjustments to the less percise human generated code.

Sort of similar to the one of the 6m omni. Instead of using twin-lead, this design makes use of a more or less regular double bazooka antenna (coaxial dipole). Your attention shall be drawn to the available standart literature, such as Rothammel. In order to "compute" the dimension, Karl Rothammel mentioned that the total length of the dipole shall be 95% of the free-space wavelength. The short-circuit bridges (closing the folded dipole) are to be placed at a distance-fraction being equal to the velocity factor of the coax cable used, which will be 66% using RG-58 or RG174.

A microprocessor based interface designed to go between a standard Morse code key and a radio transmitter. The circuit receives a signal from the key, processes it, and re-transmits it to the radio.

Printed circuit board fabrication

This transverter was built in 1994 and include in this page a pdf with circuit board, and a version of this project for 70MHz.

Sell quality electronic components, equipment, and accessories. Test equipment, RF Modules, Power supplies, PCB, Stepper motors.

Use these Variac auto transformers for specific application requirements that include, but are not limited to, home coffee roasting, tube amps, and more.

This FM wireless mike can transmit voice signals to any FM Radio receiver 100 meters away.

A discharge circuit which you could use to cycle the batteries