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Radio reef your QTH in the Caribbean St. Croix, US Virgin Islands

This design was adapted from an article in the ARRL Handbook and built with simplicity and duplicity in mind. This antenna is a vast improvement over a standard dipole with a forward gain of around 8db with a front to back ratio of 10db.

CW paddle made with a steak knife some simple hardware and a stainless steel fork

Add-in module to Microsoft Excel, contains a set of radio amateur relevant special functions: DistSphericLocator(Loc1; Loc2) Calculates the spheric earth model distance between two locators [km] DirSphericLocator(Loc1; Loc2) Calculates the spheric earth model direction from Loc1 to Loc2

Presents a detailed construction guide for a **Quadrifilar Helix Antenna** (QHA) optimized for 137 MHz, specifically for receiving weather satellite transmissions. The resource outlines the author's experience building previous QHA designs, highlighting challenges with tuning and nulls, and then focuses on a refined design by John Boyer, documented by Steve Blackmore, which proved easier to build and yielded superior reception. The guide provides precise element dimensions, including 1.5m of 32mm PVC pipe for the mast and 8mm soft copper tubing for the helix elements. It specifies lengths for horizontal tubes (190mm, 90mm) and helix elements (903mm, 1002mm), along with instructions for drilling, assembly, and forming a **balun** by wrapping RG58 coax around the mast. The text emphasizes critical steps like ensuring elements are square and twisting in the correct direction to avoid phase issues. It includes references to original QST articles by Buck Ruperto (W3KH) and the WxSat program for decoding satellite transmissions, contextualizing the antenna's purpose. The article concludes with a sample NOAA 12 image from September 1998, demonstrating the antenna's reception capabilities.

This purpose of this page is to give a brief description of a 70 MHz transverter that has been published in the Danish amateur radio magazine "OZ"

A 5/8 wavelength mobile whip antenna for 2 meters can be constructed from a 5-foot CB helical whip, requiring the removal of original wire and installation of a new radiating element made from coax braid. The design incorporates an 8-turn loading coil with 5mm spacing, fabricated from the original whip wire, and utilizes approximately 1400mm of RG-58 coax braid for the radiating element to enhance flexibility and bandwidth. Final whip length is approximately **1350mm** from base to braid end, with tuning adjustments made by trimming the braid. Dual-wall 12mm heat shrink, such as _Jaycar WH5643_, is recommended for weatherproofing and stabilization, costing around $4.50 per 1200mm length. Achieving a 1.1:1 VSWR may not be feasible; a 1.5:1 VSWR is considered acceptable. Optimal mobile mounting is centered on the vehicle roof to minimize radiation pattern variations.

A simple circuit which will generate a 700 Hz tone into any FM transceiver allowing an amateur to practice CW with another amateur on a 2 meter simplex frequency.

A simple quarter-wave length vertical for 40m band using a 12 m spiderpole

Free format input, User selectable usage of reports, counters for DXCCs, WWL, DOK/UK Counties/CQ/ITU/States/Provinces and more

Comparison of several UHF antennas by DF9CY

A five element quad antenna for 144 MHz DIY Project. This 2 Meter 5 Element Quad antenna was modeled using EZNEC, with a boom from a UHF TV antenna and CPVC pipe for spreaders. Constructed for 146MHz, it exhibits a gain of 10.7dB and an impedance of 75 ohms. Real-world results surpass the HT antenna, reaching over 20 repeaters up to 75 miles away. The design, costing around $10, employs simple tools for assembly.

A simple 7 bands off-center dipole wire antenna designed to work on 80 meters band and that can cover also 40m 30m 20m 15m 12m 10m with acceptable SWR

Wire beam antenna for the bands 6m, 10m, 12m, 15m, 17m and 20m

VU3NSH article on high current universal supply for rigs

G0KYA's Amateur Radio Blog, make a 2m Slim Jim antenna out of 300 Ohm ribbon cable.

This HALO design is not ground dependent and can be mounted atop a section of PVC.

An easy mod to make the 1st IF of the Icom IC-7600 accessible and connect to a cheap RTL SDR dongle by VE4NSA

Information on licensing abroad for radio amatuers by OH2MCN, Veikko Komppa

A Half wave antenna has a high impedance feed point. This can be matched using a 1/4 wave stub matching section and converts the 40m vertical into an L-shaped 20m J-Pole antenna. The 300 ohm feeder used for this purpose must be kept away from the ground.

High gain, good pattern and acceptable bandwidth. These aims can be realized with a radiation-resistance of 25-35Ohms, because the 28-Ohm-feedpoint is very simple to match.

Original article published on February 1992 on 73 Amateur Radio Today about the 2m and 70 cm copper cactus J-pole antenna

jpole 2mtr 70cms homebrew antenna

Demonstrates the design and construction of a compact, portable multi-band mini-delta loop antenna, specifically optimized for /P (portable) operations from remote locations like Scottish islands. The resource covers the theoretical underpinnings of half-wave loops, contrasting closed and open configurations, and then details the application of a folded dipole principle to achieve a 50-ohm match for direct coax feed. It presents empirical formulas for calculating element lengths, considering the velocity factor of common wire types, and provides a detailed example for a 20m (14.175 MHz) version. The article includes a comprehensive table of dimensions and allowances for a five-band (20m, 17m, 15m, 12m, 10m) mini-delta beam, along with construction hints for the central support and balun. It specifies a 1:1 trifilar balun wound on a ferrite rod and describes the antenna adjustment process using an _MFJ-259B Antenna Analyser_. Initial test results indicate an SWR of 1:1 at resonance and a bandwidth of approximately 240 kHz on 20m, even at a low height of five feet above ground. The distinctive utility lies in its focus on a practical, easily deployable beam antenna for portable DXing, offering a viable alternative to more complex or larger arrays.

An Attic version for limited space applications by NW9T

A Quagi antenna project with pictures and dimensions for a UHF Quagi antenna

GW4ALG's _136 kHz Pages_ document the evolution of vertical antennas for the 2200m band, starting with a prototype mounted on a house wall. This initial design, despite achieving the first **395 km** GM-GW QSO, suffered from significant insulation breakdown, high RF losses due to proximity to the house, and difficult tuning adjustments. The author details the challenges of maintaining resonance and matching with a variometer in the loft, noting that adding three earth spikes offered no measurable improvement over a simple water tap connection. The subsequent experimental 12m vertical, relocated away from the house, significantly reduced dielectric losses and proved far more effective. This antenna enabled GW4ALG to set a world DX record on 136 kHz with a **1916 km** QSO to OH1TN, and an intra-UK record of **703 km** to GM3YXM/P. The resource further explores the use of helium-filled balloons to extend the vertical radiator, achieving heights up to 27m, typically 20m, for enhanced low-band performance. Practical advice on balloon types, inflation, and critical insulation between the wire and balloon is provided, emphasizing safety and avoiding arcing.

On this page is the design for Dual Band 2M / 70cm antenna with 3.2mm elements. The antenna has a 50 ohm designed driver. This Yagi has a unique element called a Open Sleeve

Generic PI4 + CW + Carrier Arduino Beacon Controller with interfacing to Analog Devices AD9833 DDS AD9850 DDS, AD9851 DDS, AD9912 DDS , AD9913 DDS, ADF4350 and ADF4351 synthesizers, ADF5355 synthesizer, ADF5356 synthesizer, Radio modulated by an audio soft-DDS Reverse DDS, RDDS microwave unit, Silicon Labs Si5351A programmable clock generator, Silicon Labs Si570 programmable XO/VCXO, Texas Instruments LMX2541 synthesizer

This article presents a technical investigation into spurious emissions from the Yaesu FT-847 transceiver when operating on the 70MHz (4-meter) band. The author discovered significant problems with both factory "UK spec" and modified units. Spectrum analysis revealed that when transmitting at 70.2MHz, the radio produces numerous spurious signals, with the most prominent emission at 45.6MHz measuring only 3dB below the fundamental frequency. The study also documents poor power efficiency on 4m (10.3% at 30W output) compared to 6m operation (23.5% at 30W). Tests verified that jumper configurations had no effect on filter selection. The author warns that using these radios on 4m may violate license conditions due to excessive spurious emissions.

A dipole for 2m, 4m, 6m band an hamdwritten note for a homemade vhf antenna that can be tuned across the VHF band

A 2m Moxon antenna project, designed for the 145 MHz amateur radio band, provides a compact, directional solution for VHF communications. This resource details the construction process, specifying materials like PVC pipe for the frame, copper wire for elements, and a SO-239 connector for the feedpoint. The design emphasizes ease of build for hams seeking a gain antenna with good front-to-back ratio for local ragchewing or contesting. The project outlines precise element lengths and spacing, crucial for achieving the desired impedance and radiation pattern. It includes a visual representation of the antenna's dimensions and assembly, allowing for straightforward replication. The Moxon's inherent characteristics offer a practical alternative to larger Yagi arrays, particularly for portable operations or restricted spaces, while still delivering effective directivity and gain.

The **2M Moxon antenna** design presented operates at 144 MHz, providing a compact, directional solution for VHF communications. Construction involves aluminum tubing for the elements, with specific dimensions for the driven element and reflector to achieve optimal performance. The design aims for a good front-to-back ratio and a relatively low SWR across the 2-meter band, making it suitable for portable or fixed station use where directivity is beneficial. Element lengths are critical for proper resonance and pattern. The driven element measures approximately 38.5 inches, while the reflector is slightly longer at 40.5 inches. Spacing between the elements is 12 inches, forming the characteristic Moxon rectangle. This configuration yields a gain of about 5.5 dBi and a front-to-back ratio exceeding 20 dB, which is advantageous for reducing interference from unwanted directions. Feedpoint impedance is close to 50 ohms, allowing direct connection to coaxial cable without complex matching networks. The antenna's lightweight structure, typically under 2 pounds, facilitates easy deployment and rotation, making it a practical choice for field operations or as a compact home station antenna.

A free to download and print, paper log sheet useful for portable amateur radio operations, in a PDF file.

The Construction Principles for Duoband-Yagis 2m/70cm by DK7ZB

Backpacking, boating or mountaintopping ? Invest your time and pack this novel directional gain antenna on your next expedition

Building a cavity resonator for 144 MHz

A PDF presentation of a home made moxon antenna for 50 MHz 70 MHz and 144 Mhz. The project is mainly out of surplus plastic Plumbing pipes and clips etc, and also details of how the dimensions were calculated.

This document details the design and construction of a Vinecom 6N4 dual-band Yagi antenna for the 50MHz (6-meter) and 70MHz (4-meter) amateur radio bands. The antenna features 9 total elements (4 elements for 50MHz, 5 elements for 70MHz) on a 4.236-meter aluminum boom. Computer simulations using MMANA software predict 7.21 dBd gain on both bands with front-to-back ratios of 16.01dB (6m) and 15.37dB (4m). The design uses 12.7mm diameter elements mounted on a 32mm square boom, weighing 5.7kg total. Practical measurements with an MFJ-269 analyzer confirmed good SWR performance across both bands after element length adjustments.

The long range bandplan for 70 MHz by OZ2M

Distance and directions calculation program using both Spheric, the perfect round earth model, and Vincenty's inverse ellipsoid algorithm, the WGS 84 earth model.

This online guide details the microphone pinout for the Kenwood TR-7950 transceiver, specifically addressing the wiring configuration for a dynamic mobile microphone with a **500 Ohm** impedance. It provides a pin-by-pin breakdown for the 6-pin microphone connector, identifying the function of each active pin. The resource specifies that Pin #1 is for the microphone audio (white wire), Pin #2 controls the _PTT_ (black wire), Pin #3 activates the memory down function (blue wire), and Pin #4 controls the memory up function (red wire). Pin #6 is designated as the ground connection, while Pin #5 remains unused in this configuration. The document focuses on the physical wiring necessary to restore microphone functionality to the Kenwood TR-7950, a transceiver capable of **45 watts** output on the _2m band_. It directly addresses the technical challenge of re-establishing correct electrical connections after microphone wires have been disconnected from the connector. The information facilitates proper microphone operation for simplex QSOs and other voice communications. DXZone Focus: Online Guide | Microphone Pinout | Kenwood TR-7950 | PTT Wiring

This document contains the detailed instructions to build a homemade lindenblad antenna using a twin-lead as dipole elements. This document contains 9 pages and includes a detailed construction sequence and some drawings to build this antenna for UHF and VHF ham radio bands

Article on a 2 and 6 meters halo antennas that does not require a mast has a very low part count and can easily be built with a minimum of tools.

AM-6154 222MHz grid Conversion Information by N0UK

2 meter kilowatt linear amplifier

Receiver converter that can be plugged to the backside of the Yaesu FT-817 battery powered portable transceiver

2M Yagi made from Measuing Tape by NT1K

The GW3YDX Super Moxon antenna design improves upon the standard Moxon Rectangle by incorporating additional directors in a rectangular configuration, yielding enhanced directivity and gain. For the 6m version, modeling with 4NEC2 and EZNEC+ indicated a 3dB gain increase and a 26.5dB front-to-back ratio, with VSWR below 1.5:1 between 50.0 and 50.3MHz when optimized for 50.1MHz. This design achieves a narrower -3dB power point beamwidth of 60° compared to the original Moxon's 80°, contributing to better QRM rejection. The boom length for the enhanced design is just under 2m, approximately double the original Moxon's, with no increase in wingspan. Construction details include tubing lengths for 6m, 4m, and 2m versions, with specific dimensions provided for elements A through M, measured to tubing centers. For instance, the 6m version uses a 2160mm element A and a 2140mm element H. The design maintains a 50-ohm feed impedance, with practical models showing VSWR plots consistent with simulations after minor adjustments to driven element lengths. The article also references Moxgen software for initial Moxon parameter calculation and NEC/EZNEC model generation. The 2m Super Moxon version measures approximately 30" x 25", demonstrating the compact nature of the design across different VHF bands. The article highlights the antenna's performance in real-world DX contacts on 6m, achieving contacts with over 80 stations in the USA from a modest QTH.

Building a 2 metre 144MHz VHF Yagi beam antenna, designed for portable use.