Search results

AB4GX K4EAA Mononband yagi antenna for 20 Meters

Pre amplifier using a 2N5109 for the 160 meters band

A three-frequency multi-band dipole that can be extended easily to additional bands. This article includes a multiband fan-dipole antenna for 80-40-20-10 meter band.

A multi band version of the EH antenna by Emilio S. Campus IS0IEK

The Upside-Down Umbrella Antenna by Don Keith N4KC

The ZS6BKW wire antenna, a variant of the G5RV, utilizes a specific 13m (42.6 ft) length of 450-ohm window line as its matching section, feeding a 28.5m (93.5 ft) flat-top element. This design aims for lower SWR on 40m, 20m, 17m, 12m, and 10m compared to a standard G5RV, often achieving SWR values below 1.5:1 on these bands without an antenna tuner. The feedpoint impedance transformation provided by the window line allows for direct connection to 50-ohm coax on multiple bands. F4FHH's experience involved constructing the ZS6BKW and evaluating its performance against an _OCF dipole_ (Off-Center Fed) on various HF frequencies. The article includes observations on SWR readings and operational effectiveness, highlighting the ZS6BKW's suitability for multi-band operation. The antenna's overall length, including the flat-top and window line, is approximately **41.5 meters** (136 feet), making it a significant wire antenna for fixed station use. Comparative analysis with the OCF dipole provided practical insights into the ZS6BKW's advantages and limitations, particularly concerning bandwidth and tuner requirements.

A project to build a cross band repeater using a pair of Baofeng UV5R handheld transceivers.

The following are the opinions expressed by various amateurs

Build the Moorabbin, a regenerative receiver for the AM broadcast band by Peter Parker VK3YE

Multiband no trap no gap antenna. This Antenna is a small wonder, easy to build and allow you to work all HF spectrum with your TRX and it's internal ATU.

FT-1000MP Automatic Band Selection Interface Bob Wolbert, K6XX

The following frequencies are assigned to datacommunications in the HF bands within the UK By RSGB data communications committee information.

A project for a multiband HF windom antenna by VE2CV and VE3KLO

General purpose RF Wideband PreAmp based on BSX-20 transistor with a frequency range 14-550 MHz

A monoband end-fed half wave for 10m, 20m or any other HF band, includes a PDF with detailed information to build your own monoband or multiband antenna

A telescopic pole that you adjust to suit the band you're working on , tested on 40 20 and 15 meters band by M0PZT

High speed silicn diodes work well as RF switches. This article describes how to use diodes for selecting two or more filters ARRL QST article by W1FB

Dual band vhf uhf dipole antenna by DL7JV

Different band dipoles can be put together with a single feed, learn how by W8HDU

This is a 200 Watt PEP step up transformer for end fed full and half wave antennas without radials, designed as a 200 Watt PEP

This project is an interface box for the Yaesu FT-817 that includes a band output port, a computer serial interface, and a remote interface for the FL-7000 (and Quadra?) solid state power amplifiers

Operating a ZS6BKW antenna often involves understanding its lineage from the _G5RV_ design, with specific modifications by ZS6BKW to optimize performance on several bands. Through computational analysis and field measurements, the antenna's dimensions were refined to allow operation on 10, 12, 17, 20, and 40 meters without an antenna tuner. For 80, 30, and 15 meters, a tuner is necessary, though efficiency on 30 and 15 meters is noted as not particularly high. The physical configuration consists of two 13.755-meter radiating elements fed by a 12.20-meter section of 450-ohm ladder line. Tuning the antenna on the 20-meter band is critical, and any deviation in the ladder line's characteristic impedance necessitates recalculating the element lengths. The design is also referenced in the 12th edition of _Rothammel's Antennenbuch_, page 219. Proper common mode current suppression is crucial at the transition from ladder line to coaxial cable. This can be achieved with a common mode choke, such as several turns of coax wound into a coil or over a ferrite toroid like an Amidon T130. While a 1:1 balun is an option, it may introduce issues.

The Classic Multiband Dipole Antenna QST article. The open-wire feed line dipole antenna is easy to install and offers surprising performance on several bands. You can install it in almost any configuration; it does not have to be strung in the traditional horizontal flat top

Sharing information on Topband Homebrew Antennas, Base & Mobile

This project will enable you to build a monoband long wire inverted vee with 3/4 wave length sides that will have a bit of gain

A compact Quad Antenna for the HF Bands by GM0ONX

PA5DD version of the dual band yagi antenna for 50 and 70 Mhz

Why Beverages need good transformers by VK3APN

This antenna consists of 4 resonate dipoles made from 12 insulated copper electrical wire. The dipoles are resonate on the following bands: 6 meters, 10 meters, 12 meters and 17 meters.

A compact multiband wire antenna suitable for portable operations.

Build your own multi-band mobile ham antenna with a Hamstick

You can use almost any Icom handheld to contact your 2720H back in your vehicle for crossband repeating.

An efficient 2 meter antenna disguised as a TV Satellite dish. This vertically polarized horizontal slot antenna, cut into the reflector of a TV dish, might be the ultimate stealth antenna.

Simple, easy to build, low cost, compact, multiband By Robert Wilson, AL7KK

Ari Milano draw and keep updated these pdf files representing the "radioamatori" bandplan, with notes in italian

A multiband dipole antenna that can work on 15 20 and 40 meters band made with common materials

This vertical antenna consist of a 18 meters telescopic pole and allow operations from 160 to 30 meters band, project by Daniel Zimmerman N3OX

A 1:1 current balun that offeres a almost flat swr curve from 1 to 30 MHz

A 67 feet long dipole doublet antenna

All Band HF Doublet for operation over all HF bands including 160m.

This project produces an inexpensive, multiband, end fed HF antenna matchbox, quick and easy to setup. This project creates a trifilar wound, 9:1 UNUN toroid matching transformer. Handles 100W and need an antenna tuner.

The Icom IC-7300 is a popular HF transceiver among amateur radio operators, known for its advanced features and performance. This modification guide focuses on enabling extended transmission capabilities, specifically for MARS and CAP frequencies. The instructions are based on the work of PA2DB and include detailed steps for removing specific diodes to unlock additional frequency ranges. Before proceeding with the modification, users are advised to take necessary precautions, such as ensuring the radio is powered off and using ESD protection. The guide emphasizes the importance of using appropriate soldering techniques and tools to avoid damaging sensitive components. A video demonstration is also provided to assist users visually in performing the mod. While this modification can enhance the functionality of the IC-7300, it is crucial to note that it may void the warranty and should be undertaken at the operator's own risk. The guide serves as a valuable resource for those looking to expand their operating capabilities with this versatile transceiver.

This is a 6 band receive only filter designed to protect your receiver front end and provide 45dB reject at the stop bands. This is a 6-band receive only filter designed to protect your receiver front end and provide 45dB reject at the stop bands. Stop band reject may be limited by the relay isolation. Worse case isolation is at 28 MHz or 35 dB or better. Relay K3/K8 protects the filter during transmit via the PTT line. A 25-50ms delay must be used between transmit and PTT. Do not rely on your radio to provide adequate delay with out using the PTT. You logging software must be set to allow a delay between PTT and time of 1st transmit. This filter will not work with VOX or QSK keying as you will damage the filter.

A multiband quarter wave vertical antenna that works on 5 bands.

Conversion of Zetagi HP201 SWR wattmeter for HF Amateur Bands by G8ODE

A VHF power amplifier made with two cheap RF transistors, 2N3924 as driver and a BFS22A for final stage, giving an unexpected output power of 7-8 watts maximum

Antenna experiment - Delta Loop for 7 Mhz band by AG1LE

This strange looking antenna is a combination of Coupled-Resonator principle by K9AY and a quarter stubs to achieve low angle radiation pattern. Designed with 4nec2 NEC based antenna modeler and optimizer for 145/220/440MHz bands

A MRF141G 3-175MHz Broadband Power Amplifier DL4MEA 02/1998

Demonstrates the product line of _LZ Antenna Ltd._, a Bulgarian manufacturer specializing in amateur radio antennas and custom electronic devices. The company focuses on robust, high-quality HF multiband Yagi and vertical antennas, leveraging over 20 years of experience from founder Georgi Georgiev in radio amateur development. Featured models include the LZA 8-4, LZA-10-3, and the LZA-7-3A WRTC 2022, alongside various rotary dipoles like the LZA1 40/30m. Provides specifications for several Yagi antennas, such as the LZA-9-5, LZA-13-7, and LZA-6-3 (a 6-element, 3-band design). The company emphasizes applying "leading edge technology" to high-frequency communication equipment production, with products designed for durability and performance. The LZA-10-5 Yagi offers **12.5 dBi** gain on 10m, while the LZA-13-7 provides **13.2 dBi** on 20m, showcasing competitive gain figures for DXing and contesting.