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An end-fed halfwave antenna for 20 meters band with balun pictures and description by PD7MAA

January 1955 QST article by W5DQV about constructing a Cubical Quad antenna for 14MHz PDF File

Over 1,000 stations in approximately 60 countries were worked using this modified twin-lead folded dipole, demonstrating its effectiveness with just 4 watts on 20 meters. This design, adapted from an ARRL Handbook concept, eliminates the shorting strap found in traditional folded dipoles, simplifying construction while maintaining performance. It utilizes readily available 300-ohm TV antenna feeder ribbon, making it a cost-effective solution for radio amateurs. The antenna's robust construction allows it to handle up to 100 watts without issues, even without a **balun**. The inclusion of a variable trimmer capacitor at the stub provides flexibility for tuning across different frequencies within a band, a practical feature for operators using transceivers like the Icom 735. Formulas are provided to calculate the precise dimensions for any desired operating frequency, enabling customization for various **HF bands**.

Optimizing DX chasing efforts, this software provides a refined approach to monitoring the DXCluster. It allows operators to configure specific filtering criteria, ensuring that only relevant DX spots are displayed, thereby reducing clutter and focusing attention on desired entities or bands. The application integrates alarm functionalities, notifying the user when a spot matching their predefined parameters appears on the cluster, which is particularly useful for working rare DX or specific band slots. Spot supports both macOS and Windows operating systems, offering a cross-platform solution for a broad user base. Its design emphasizes user control over the displayed information, moving beyond a simple stream of cluster data to an actionable intelligence system for DXers. This client aims to streamline the process of identifying and pursuing DX opportunities. While the software was previously a commercial product, the developer, K3NC, has retired and made registration files for DXBase 2007 available for free, along with a utility to generate registration keys for that specific version. This allows continued use of the DXBase 2007 logging software, though it's important to note the 64-bit OS compatibility modification required for generated registration files.

How to build your own beverage antenna for 80-160 meters band by K5ZD

An Off-center-feed antenna that covers 80, 40, 20, 17, 15, 12, 10, and 6 meters

The KK7UQ computer to radio interface, sound card interfaces, IMD meters interface products

The webpage provides information about the Citizen Band mailbox DBO274 in Germany, with HTTP/telnet-access. It covers topics related to CB Radio, Packet and Digital emissions, and eleven meters band.

A simple RF power amplifier initially designed for 40 meter band can work on 10 15 20 40 80 meters

A magnetic loop antenna for 7 Mhz by ZL1BJQ

A project for a home made 5 element yagi-uda antenna for 2 meters, covering 144-148 MHz band by N1BMX

Details Guglielmo Marconi's foundational contributions to radio communication, highlighting his 1898 Patent **7777** which introduced tuning circuits for independent simultaneous communications. Chronicles the historic transatlantic reception of the Morse code letter 'S' on December 12, 1901, from Poldhu, Cornwall, to St. John's, Newfoundland, a distance of over _3,500 kilometers_. The exhibit showcases early Marconi 10-inch spark transmitters, identical to those used on the _Titanic_, alongside Canadian Marconi crystal detector models. It also features high-end commercial receivers like the IP501, weighing **87 pounds** and originally priced at $595.00, demonstrating the robust construction and technological advancements of the era.

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

An home made Z-Match antenna tuner unit that cover all HF bands between 10 and 160 meters

The two linear amplifiers are ment for use with QRP SSB/CW/FM/AM transmitters on the amateur bands 15 and 17 meters can be powered from a 12 volt DC supply by ON6MU

3 Element reversable quad antenna for 40 meters band

How to operate on 10 and 20 meters in limited space with this trapped dipole.

5/8 vertical groundplane antenna for six meters band

A shortened 160 meters band antenna for hams who do not have 260 ft of space, based on a open-wire-fed short dipoole

The circuit described below will substantially reduce or completely eliminate interference from almost any local source whilst leaving the wanted signal relatively unaffected, even though it may be on the same frequencey by TREVOR, G3ZYY

A short dipole wire antenna for 40 meters band. It is a folded dipole that do not make use of coils and can be used either in horizontal or inverted V configuration

An attic antenna for 40 and 80 meters band by NS1W

A 2W 80 meters transceiver assembled into a toaster case.

Operating on 160 meters from a city lot is always a challenge. Here's how K9YC does it.

The 9A3MR contest QTH rental provides a fully equipped amateur radio station for DXpeditions or radio holidays on Murter Island, Croatia. The station features a Drake TR7 transceiver and a 16-meter tower with a rotator, suitable for various HF operations. Accommodations include a four-room apartment and a studio apartment, both within 200 meters of the beach, offering amenities like parking and a barbeque area. This QTH is located in Jezera, a fishing village with local stores and restaurants within a five-minute walk. While Murter Island itself does not qualify for IOTA due to a bridge connection, the Kornati Islands National Park (IOTA EU-170) is only 10 nautical miles away, with daily tourist tours available. The Krka National Park is also accessible by car, approximately 25 km distant, providing additional recreational opportunities.

The Collins TRC-75 autotune linear amplifier, owned by JF2SVU, is presented with a focus on its internal modifications. This QRO amplifier utilizes three 4CX250 tubes in parallel for its final stage, delivering 1 KW output power. Notably, the amplifier achieves full power with only 100 mW of RF input, a characteristic often associated with Collins designs. The original 400 Hz power supply has been converted for easier shack integration, and the entire RF and power supply sections have been rehoused into a compact, clean enclosure. The control unit, positioned above the amplifier, features three meters for individual vacuum tube IP monitoring and a multi-meter on the right. A dedicated 7 MHz receiver, recently completed, is also part of this integrated system. The autotune functionality means the main amplifier unit only requires connections for power, control, and coaxial cables, simplifying its operation. Key components like the 4CX250 tubes and NF capacitors are visible, along with the gearing mechanism for the final tank circuit. A timer and relay system manages high-voltage delay and cooling fan off-delay, although the cooling fan's airflow is noted as somewhat insufficient. A central volume control, which experienced a contact issue, is also highlighted.

Cheap UHF antenna plans for 2 meters and up including 421 1296 and 902 Mhz

If you have space constraint at your QTH for a HF antenna, you can try contructing this HF magnetic loop antenna for 40-20 meters bands

Shortened vertical antenna for 40 meters band an homebrew project

A well documented article about construction and analysis of a horizontally polarized halo antenna for 6 meters band by Dr. Carol F. Milazzo, KP4MD

A trapped dipole antenna based on the orignal W3DZZ antenna design resonating on 80 40 20 15 10 meters

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.

A 40/80 meters dipole made with two loading coils based on a project by IK1ZOY

A QRP transceiver for 80 meters band by W1FB

2,6 and 10 meters beacon located at Lake White, Ohio

A vertical monoband antenna design that can work from 6 meters to 70 cm by F5ZV in French

3d parts printed to build an EZ-Lindenblad 2 Meters LEO Sat antenna as designed from Anthony Monteiro

A project of a bobtail-curtain antenna for 10 MHz

Accurately determining an antenna's feedpoint impedance is crucial for optimal performance, especially when experimenting with new designs or making adjustments. While SWR meters provide basic information, a full complex impedance measurement reveals the resistive and reactive components, which are essential for proper matching. Modern antenna analyzers, like the _Palstar ZM30_ or MFJ259B, simplify this task, but measurements taken through a transmission line require careful interpretation due to impedance transformation. This resource details a calibration method to precisely account for the effects of the feedline. It explains how a transmission line can significantly alter the measured impedance, illustrating this phenomenon with a Smith Chart example where an 80m antenna's [22 + j6] Ohms feedpoint impedance transforms to [82 + j45] Ohms after a 10m line. The guide demonstrates using a transmission line calculator applet, such as the one by W9CF, to reverse this transformation. It outlines the process of calibrating a specific length of RG174 coax, showing how an initial 26ft estimate was refined to **25.85ft** to accurately predict a known 22 Ohm load, significantly improving accuracy over uncalibrated results.

A 21 MHz Four Square Beam Antenna This popular antenna for the lower bands, can also work well on 15 meters, QST Article

An homemade portable trapped dipole antenna for 40 and 80 meters band with an optional extension for the 20 meters.

DX_Central, a compact desktop application, provides amateur radio operators with critical propagation data by aggregating solar statistics and imagery from various authoritative sources. This includes real-time information from agencies like NOAA and NIST, offering insights into current space weather conditions that directly impact HF propagation. The software is designed for both Linux and Windows operating systems, making it accessible to a broad range of hams. It presents a concise overview of solar activity, which is essential for planning DX operations and understanding band openings and closures across the HF spectrum. Operators can utilize the displayed solar flux index, K-index, and other relevant parameters to make informed decisions regarding their operating times and target bands, optimizing their chances for successful long-distance contacts.

A SSB CW transceiver for six meters band with schematic and block diagram

Bird Technologies supplier of RF products, like RF Meters, Bird 43, VNA, Spectrum analyzers, attenuators, transmitters combiners, dummyloads, terminators and replacement parts

A power line noise eliminator designed to eliminate QRN expecially on 40 meters band.

Extension to an existing fan dipole originally modeled for 40 20 and 6 meters. This modification will add 80 15 and 10 meter bands.

Controlling amateur radio transceivers remotely often requires dedicated software to interface with the radio's CAT (Computer Aided Transceiver) system. CATSPAW is a software utility specifically developed by N2OHZ for the Yaesu FT-100, facilitating computer-based control over various radio functions. The software provides an interface for adjusting parameters such as frequency, mode, and other operational settings, which can be particularly useful for remote station operation or automated tasks. While the specific features and user interface details are not extensively documented on the download page, the primary function centers on providing a digital control layer for the _FT-100_. This allows operators to integrate the transceiver into a larger station setup that might include logging programs or digital mode applications, enhancing the overall operational flexibility. The utility's design focuses on direct control, leveraging the radio's internal command set. As a downloadable executable, _CATSPAW_ represents a common approach to radio control software from its era, offering a direct link between a personal computer and a specific transceiver model.

A Slinky-based doublet or loaded vertical QRP antenna tested for 40 meters band

A compact antenna for 160 meters, suitable for hams tha want operate top band buh have a limited space

Six meters radio club, promote and preserve 50 mhz operations in italy