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This PDF document details the construction of a **70 MHz** Big Wheel antenna, a horizontally polarized omnidirectional array. The design utilizes three full-wave loops, each approximately **2160 mm** in diameter, arranged in a triangular configuration. The resource provides mechanical dimensions for the antenna elements and a comprehensive bill of materials, specifying component quantities and types, such as M8 stainless steel bolts, 15x15x1.5 mm square aluminum tubing for spacers, and 8 mm aluminum rod for the arcs. The central hub is constructed from two 160x160x8 mm aluminum plates, with four 40 mm long polyamide insulators supporting the radiating elements. The feed system incorporates a 50 mm diameter aluminum pipe for mounting and a matching stub constructed from a 120x20x2 mm aluminum sheet, connected via M8x10 mm bolts. The resource includes a diagram illustrating the mechanical dimensions and assembly points, including the N-connector fixing point and the center conductor attachment. The project was published on May 25, 2011, by Peter OE5MPL and Rudi OE5VRL. DXZone Focus: PDF | 70 MHz Big Wheel | Mechanical Dimensions | **2160 mm** loop diameter

Most people are not familiar with antenna tuners and what a antenna tuner actually does.

Homemade Loaded Coil Dipole ( w8010 diamond ) for 10, 15, 20, 40 and 80 meter

A PDF File of a Maria Maluca multiband HF antenna with schematic diagram, dimension and plan

A google map of the UK amateur radio repeaters with clickable information

Ever need a way to estimate the amount of wire to add to or remove from a center-fed wire dipole antenna to achieve resonance at a desired frequency? This article help to determine correct wire lenght.

70 MHz jpole half wave antenna by G7OGQ and G8CVF

An interesting article on loading short vertical monopole antennas, representing six different methods. Base loading, Center Loading, Top Loading, Continuous loading, half and half loading and capacitive top loading.

History of codes of the world, russian codes, visual codes, and al long collection of telegraph codes as used worlwide including the international morse code and the relative variations

A short multi-band vertical antenna

Learn how to start using ham radio satellites for your DX contacts, PDF presentation by Dave Long

The X80 multi-band HF vertical antenna, a commercial iteration of the Rybakov design, exhibits a physical length of 5.5 meters, or approximately 18 feet, and is constructed from aluminum tubing. It operates as a non-resonant vertical, requiring an external antenna tuner for impedance matching across its intended operating frequencies. The antenna's design incorporates a 1:4 UNUN at its base, facilitating a nominal 50-ohm feed point impedance for the coaxial cable. Performance observations indicate effective operation on 40 meters, 20 meters, 15 meters, and 10 meters, with reduced efficiency on 80 meters and 160 meters due to its relatively short electrical length for these lower bands. Comparative analysis with a G5RV dipole and a half-wave end-fed antenna reveals the X80 offers a lower take-off angle, beneficial for DX contacts, particularly on the higher HF bands. Field tests conducted with an Icom IC-706MKIIG transceiver and an LDG AT-100ProII autotuner demonstrate the X80's ability to achieve acceptable SWR across 80m through 10m. The antenna's compact footprint and ease of deployment make it suitable for restricted spaces or portable operations, though its performance on 80 meters is noted as a compromise compared to full-size resonant antennas.

A comparison of multiband dipoles, including jumpered dipole versus fan dipole antennas, dipole fed by ladder line, resonant dipoles antennas. ARRL lab notes

The ZS6BKW multi-band antenna, an optimized variant of the classic G5RV, is presented with detailed construction and tuning instructions. This resource outlines the antenna's design principles, which were developed by _Brian Austin (G0GSF)_ using computer programs and Smith charts to achieve optimal dimensions. It provides specific guidance on calculating and adjusting the lengths of the radiators (L1) and the matching ladder line (L2), emphasizing the critical role of velocity factor (VF) in achieving resonance. The article includes a step-by-step procedure for empirically determining the VF of ladder line using an antenna analyzer, ensuring accurate physical lengths for the matching section. It details the tuning process for the radiators, offering practical tips for incremental adjustments to achieve the best SWR curve. The resource presents SWR measurement results obtained with an _AIM-4170C_ analyzer across multiple bands, alongside predicted SWR graphs from an AutoEZ model. It confirms successful contacts on 80, 40, 20, and 17 meters, including a **17-meter DX contact** to Italy. EZNEC and AutoEZ models for the ZS6BKW antenna, covering 80 through 6 meters, are provided for download, allowing further analysis and customization. The document specifies component details, such as the use of Wireman 554 ladder line and #14 AWG THHN copper wire, and discusses the antenna's performance characteristics, noting high SWR on 15 and 30 meters but successful tuning on 6 and 80 meters with an external tuner.

The RasHAWK team has used a Raspberry Pi as the basis for a networked RF sensor capable of supporting spectrum monitoring, signal intercept and direction finding (DF) operations.

In this PDF article Zack Lau describe how to homebrew a four element yagi beam antenna for 50 MHz band, including how to build mounting blocks and tubing clamps to hold elements.

A project for a 50 MHz moxon rectangle antenna

Cabrillo2Adif A software for converting the radio logs from Cabrillo to Adif log format (for Mac OS X)

Why all the mystery surrounding baluns ? To use or not to use baluns

The Packet Radio beginners guide to packet radio operating by Buck Rogers K4ABT

A bycicle ham radio station setup, with full band coverage

An interactive repeater map that uses google maps to display location of repaeter types available in Italy by Andrea IW0HOG

A simple to build full length 20/40 dipole antenna to be used in inverted vee configuration

Heathkit SB-220 Amplifier modification by KE5YA

This project produces a sturdy tripod for small vertical antenna support using readily available electrical metal tubing (EMT) or conduit

A trap on the coaxial cable, also known as choke, helps to eliminate the sneaking of the reflected RF- energy to the shack. The trap can be made from the coaxial cable that feeds the antenna

After you have build this antenna, you may not need anything else. This article shows how to build a VHF j-pole antenna and how to protect it by inserting it into a PVC tube, the correct way.

In this article the author describes some new designs of ferrite loaded chokes for suppressing unwanted common mode currents at HF applied to feed lines like choke baluns, but also in the shack, applied to various coaxial, mains and data cables

An indeal stealth antenna made by multiple quarter wave verticals, supported by a tree.

Technical supplement with schematics of the Yaesu FT-2800M Yaesu Transceiver

APRS web map with weather, telemetry, messaging and a bulletin board. Google Maps and Google Earth views update automatically in real time. 14 languages.

Butternut article on radials usage on vertical and ground plane antennas

A presentation of a HF multi-band sloper antenna. This antenna project is for low band operations, and antenna presented in this article works on 40 80 and 160 meters band. Article is in Polish.

Schematic diagram of the VLA 200 power amplifier by RM Italy

VHF Power amplifier VLA 200 english manual

2 transistor transceiver for 28MHz CW

PIC micro controller based frequency counter with LCD readout

Designing and constructing portable wire antennas for HF operations, this resource explores several configurations including the _foldback dipole_ for space-constrained setups and an inductively shortened dual-band dipole for 20m and 40m. It details the calculation of inductance for shortened elements, providing a Visual Basic 6.0 program screenshot that illustrates determining coil parameters like turns and length for a **25.5 uH** inductor. The document emphasizes practical considerations such as adjusting wire lengths for optimal SWR, noting that a dual-band dipole achieved SWR below 2:1 on both 20m and 40m, with careful adjustment bringing it under 1.5:1. Further, the resource describes a half-wave antenna matched with a coaxial stub, a method often referred to as the _Fuchskreis_ in German amateur radio circles, to transform the high feedpoint impedance to 50 Ohms. This monoband solution, for a 20m application, uses a stub length of **2.98m** (0.216 lambda multiplied by coax velocity factor) and a shorted stub of approximately 48cm. The coaxial stub design is highlighted for its resilience to ground proximity, allowing it to be rolled up or laid on the ground with minimal SWR impact, making it highly suitable for portable QRP operations.

Download the Yaesu VX-8R Cheat Sheet PDF File

My Top Five Backyard Multi-Band Wire HF Antennas. A selection of the top 5 HF wire antennas for the backyard and for multi-band operation

Photo construction manual of a portable antenna made with two heavy duty whips by buddipole. In this article has been implemented a 50 MHz portable dipole.

Tips on winding wire coils used as inductive loads, traps, band-pass filters, are implemented in a number of amateur radio projects especially antenna projects

70 MHz transverter, 4m band, by G3XBM

Project for DXers and experimenters alike. An old article publishes by 73 Amateur Radio magazine in PDF format, where all the components required to build your own HF spectrum analyzer may be found in a well-stocked junk box.

Building a Windom HF Antenna. A PDF file presentation about homebrewing a windom antenna for the HF bands with formulas for 40 and 80 meters bands and step by step guide on making a 4:1 balun to feed the antenna.

Review of Cushcraft MA-5B multiband Antenna after some days of usage.

Find out how much to adjust the length of a quarter wave whip or a half wave dipole rather than the outright cut-and-try method.

A home made 4:1 Ferrite QRO Bal-un with a FB 241-61 Type K

The resource details the construction of a multiband trap-style Inverted-V antenna designed for operation on 3.5 MHz, 7 MHz, 14 MHz, 21 MHz, and 28 MHz. It presents specific winding data for the traps, including the number of turns, wire gauge, and coil former dimensions, crucial for achieving resonance on the target bands. The document provides a parts list and a diagram illustrating the antenna's physical layout and trap placement. It outlines the process for building the traps using PVC pipe formers and specifies the required capacitor values for each trap. The design emphasizes a practical approach to achieving multiband operation with a single feedline, a common goal for HF operators with limited space. The document includes a table with antenna segment lengths for each band, allowing for precise replication of the design. It also offers insights into tuning and adjustment, ensuring the antenna performs optimally across the designated amateur radio bands.

Accurate frequency measurement is crucial for amateur radio operators, particularly when building or troubleshooting transceivers and test equipment. This resource details the construction of a _PIC microcontroller_-based frequency counter, providing a practical solution for precise frequency display. The design incorporates an LCD readout, offering clear visual feedback of measured frequencies. The counter can operate as a standalone unit, useful for general bench testing, or be integrated directly into a receiver. Its built-in offset functionality allows for seamless integration, enabling the display of the received signal frequency rather than the intermediate frequency. The project focuses on accessible components and construction techniques, making it suitable for homebrew enthusiasts. Key features include a measurement range up to **50 MHz** and a compact form factor.