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A homebrew spectrum analyzer, the Specan, provides a crucial measurement capability often missing from the typical amateur radio shack, allowing for detailed analysis of RF signals up to 70 MHz. This double-conversion superheterodyne receiver design incorporates 112 MHz and 12 MHz intermediate frequencies, utilizing an _Si570_ as the local oscillator for fine tuning down to 1 Hz steps. It offers two resolution bandwidths: 300 KHz for broad spectrum sweeps and 1 KHz for precise close-in distortion measurements, achieving an 80 dB spur-free dynamic range at 1 KHz resolution. The project, a reboot of the classic _W7ZOI/K7TAU_ design from November 1998 QST, integrates an _Arduino_ microcontroller for controlling the Si570, managing a front-panel LCD, and communicating with a PC for spectrum plotting. This approach significantly reduces cost compared to commercial units, making advanced RF diagnostics accessible to homebrewers. The Specan can measure carrier suppression, VFO cleanliness, antenna VSWR, transmitter harmonics, and filter passband shapes, providing insights beyond what an oscilloscope or frequency counter can offer. Construction emphasizes modularity and careful shielding, with each stage built and tested individually on unetched copper clad board. The design includes detailed instructions for integrating the Arduino, building the Si570 oscillator, and aligning the various modules, often using the Specan itself for calibration. It requires a well-regulated linear power supply and can be built with common tools and readily available components, making it a practical and rewarding endeavor for those looking to enhance their RF test bench.

An attic wire antenna with several modifications during the time. Began as a simple coax fed doublet antenna, and upgraded to a multi-band hf fan dipole, till the G5RV all deployed in an attic.

This article details the design and construction of a compact 20-meter QRP SSB transceiver by Pete Juliano, N6QW, measuring just 2 x 4 x 2 inches—small enough for a shirt pocket. Inspired by a 1963 QST design and refined from a prior version, it employs bilateral circuits, a 4.9152 MHz homebrew crystal filter, switched-crystal VXO for 60 kHz coverage (14.160-14.220 MHz), and standard components like ADE-1L mixers and IRF510 PA for 1W output. Key innovations include a double-sided PCB skeletal frame for shielding and isolation, Vectorboard sub-assemblies, and ultra-miniature relays. The bilateral receiver/transmitter shares stages, omitting AGC for simplicity, while a W3NQN LPF and optional 10W external amp enable DX contacts. Tune-up focuses on crystal matching and bias for linearity. Videos on YouTube demonstrate performance, confirming excellent stability and audio. Total cost nears $100, prioritizing portability over features like CW.

Learn how to design a Hentenna antenna, a portable asymmetrical double-loop antenna ideal for amateur HF or VHF bands. This page provides details on constructing and optimizing the antenna for maximum performance in DX communications. Discover how altering the antenna's vertical feed section can adjust the VSWR resonant frequency and how changing the support pole's position can alter the beam direction. Originally developed by Japanese 6-meter operators, the 'Hentenna' offers a unique design that allows for horizontal polarization when vertically oriented. Explore radiation patterns, VSWR charts, and antenna currents diagrams to optimize your antenna's performance for long-distance contacts.

Learn how an experienced ham radio operator rebuilt his trap dipole antenna for 30, 40, and 80 meters after a storm damage. Discover the process of upgrading to a short trap dipole for 40, 80, and 160 meters using double-wound traps made from RG-58 coax. Follow along for construction details and tips on building this unique classi.

Have you missed pileups where you can feel really important again? Or perhaps you wanted to win a contest from a place where every QSO counts double points comparing to your home country? Or perhaps you wanted to have a relaxed time with a radio shack in a subtropical place? All the above is available and waiting for you to be explored. Warm weather, blue water sea, a radio shack with good antennas….Is that what every DX-er dream about?

This webpage offers an online antenna designer tool to calculate the dimensions for constructing a double bi-quad antenna for various frequencies. The directional antenna is suitable for UHF and higher frequencies, such as WiFi, UMTS, LORA, and mobile phone networks. It provides dimensions based on the input frequency, making it ideal for hams looking to build their own antennas for specific applications. The tool also mentions using common household materials like copper wire for construction, making it accessible for amateur radio operators with basic equipment.

This article describes an HF upconverter for the FunCube Dongle Pro. Designed for radio amateurs, the converter extends reception capabilities to lower frequencies (0 Hz to 30 MHz) by mixing them with a higher oscillator frequency (100 MHz). This translates the desired signal into a range detectable by the FunCube Dongle (64 to 1,700 MHz). Key components include a double-balanced mixer and a low-pass filter to suppress unwanted signals. The project provides schematics, filter specifications, and design considerations for construction.

This page details the construction project of the 'Stone', a QRP double conversion superhet SSB transceiver for the 40m band. The project is based on a kit from Tim Walford, G3PCJ, and includes step-by-step instructions for building and testing each stage. The author has added enhancements such as a three digit frequency counter and an automatic gain control. The content is aimed at hams interested in DIY transceiver construction and includes technical details of the build process.

Designing a collapsible 6-meter beam antenna involves careful consideration of element geometry and feedline matching, as demonstrated by VE3SMA's project. The construction draws inspiration from foldable dipole concepts and established wire beam designs like the Penn. State 40m beam and the DJ4SA Spiderbeam. Utilizing **4NEC2 modeling**, the author optimized element lengths for gain and bandwidth, observing the impact of end loops on resonant frequency and the need for compensation. Feeding the approximately 25-ohm balanced antenna with 50-ohm unbalanced cable required a specialized network. This setup incorporates a choke **balun** and a matching section built from two series quarter-wave transformers using readily available 75-ohm cable. On-the-air results validate the design, including a successful 1st double hop Es QSO with 10 Watts and satisfactory performance in the CW WW VHF Contest from FN05, where 41 grids were worked with 100 Watts, showing improved performance over a simple dipole.

This webpage caters to EMRFD owners, offering insights into building popcorn receiver band-pass filters with Ladpac programs and EMRFD Chapter 3 knowledge. Through practical experiments and Ladpac tools, the author explores coupling capacitors' impact on filter response and return loss optimization. The content emphasizes empirical approaches, encouraging builders to embrace experimentation and learn from mistakes. Detailed examples and workflow suggestions aid hobbyist-level designers in creating customized filters, fostering a deeper understanding of filter design principles.

This page describes N6AQ's experience with a 160-meter doublet antenna from True Ladder Line. The operator initially attempted to install the antenna in a tree but later changed to a Rohn 45 tower for support. The antenna was upgraded to use 14ga wire instead of 16ga, and the performance was tested using an IC7300 transceiver with a 4:1 balun. Despite less than ideal setup conditions, the operator received positive signal reports on 40, 80, and 160 meters, thanks to advice from Gary at True Ladder Line.

The W6PQL 23cm Beacon Project describes a **1296 MHz** beacon designed for microwave propagation studies and equipment testing, capable of 30 watts output. It utilizes a PIC 16F628A microcontroller to generate CW and FSK keying for a crystal oscillator, followed by a series of frequency doublers and triplers to reach the target frequency. The final power amplification stage employs a Mitsubishi M57762 module, providing a robust 10-watt RF output. The design emphasizes stability and reliability for continuous operation, with the microcontroller code, written in assembly, provided for customization of the beacon's callsign and message. Originally located in CM97am and aimed at 140 true, the beacon used four 4-foot Yagis stacked vertically for a total ERP of 3kW. The article includes schematics, parts lists, and construction notes to guide builders, along with antenna pattern measurements. Although the beacon itself is no longer in service as of August 2010, the detailed documentation remains a valuable reference for amateur radio operators interested in building similar **microwave** projects or understanding beacon operation.