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A homemade tunable bandpass filter for all HF bands from 160m to 10m

This is an Android application used to remotely control several HAM radio Web SDR or any CAT enabled transceiver

An amateur radio contest log sheet printable in A4 format, useful for portable operations, free to download PDF File.

A large printable PDF file representing the world time zones. This map gives an overview of current local times around the world. If you ever asked yourself what time zone am i in, find your answer here.

This article compares two commercial vertical antennas for the 4-meter amateur radio band: the Watson WVB-70 half-wave and the Sirio CX4-71. The Watson measures 2.03m in length, costs around £40, and exhibited adequate performance but required additional waterproofing after rain affected its VSWR readings. The longer Sirio CX4-71 (3.02m) performed noticeably better, delivering signals approximately 2 S-points stronger than the Watson. The Sirio demonstrated high build quality, a stable 1.2-1.4:1 VSWR, and weather resilience, though minor VSWR fluctuations were observed during rain and frost. Both antennas are half-wave designs requiring no ground plane radials.

A page by 9A7PJT dedicated to HB9CV yagi antennas includes link to the HB9CV calculator program and some interesting plans

Useful exercise sheet to learn morse code reception. In A4 format PDF File, it contains groups of 5 characters commonly used while learning morse code reception.

An Unorthodox Antenna, originally by W3AWH is considered a multi-band antenna suitable for fixed location use and as an easily deployable portable antenna for events such as Field Days.

The information in this article has come from many amateur sources, the most notable was from WA6TEY (sk 1985) Ray Frost, who was a pioneer of VHF Quad designs and one of the best Southern California Transmitter Hunters. Ray built hundreds two meter quads in single and paired configurations as well as his famous mobile radio direction finding quad.

This document details the design and construction of the PA70H, a 50-watt RF amplifier for the 70MHz (4-meter) amateur radio band. Built around the Mitsubishi RD70HVF1 MOSFET transistor, the amplifier delivers 45-55W output with 3-5W input power while operating on 13.8V DC at approximately 7-8A. The PCB design incorporates multiple protection circuits including overcurrent, SWR, and temperature control. The amplifier features various control modes including GND PTT, +13.8V PTT, and RF VOX. Two versions are available: PA70HLI (requiring 100mW input with additional driver) and PA70H (for 3-5W input). The comprehensive documentation includes circuit diagrams, assembly instructions, and performance data showing successful operation from both 100mW and 3.5W input sources.

Paul Harden NA5N has produced a superb guide to solar activity and HF propagation for the QRPer

A moxon antenna project made with wires and fiberglass poles

5-element antenna, with which G0JJL has worked lots of EU crossband, and won the RSGB Christmas Cumulatives 70MHz section twice in a row.

HAM-IV antenna rotor repari and restore

Building the double size G5RV antenna, part list, assembly part, dimensions and assembly instruction in a pdf document

Using the Raspberry Pi to operate Weak Signal Propagation Reporter

Mountain Thunder CB Radio Group is a group of CB SSB operators that started in the Pacific Northwest, Washington State.

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

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

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

Design and build an 6 m dipole antenna from aluminum, tubing, that resembles the active element of a yagi beam antenna.

A monster magnetic loop antenna for 160 meters band. This Magnetic loop is optimized for 1840 Khz + 50 Khz. PDF Article published on La Radiospecola 10.22

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.

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

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.

The X80 is a commercial version of a so-called Rybakov vertical antenna.

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

A short multi-band vertical antenna

A project for a 50 MHz moxon rectangle antenna

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

The ZS6BKW antenna is derived from the G5RV by Brian Austin G0GSF who developed computer programs that were used in conjunction with Smith charts to calculate the optimum dimensions for his variant of the antenna.

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

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.

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

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

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

A bycicle ham radio station setup, with full band coverage

Heathkit SB-220 Amplifier modification by KE5YA

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.

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

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

Butternut article on radials usage on vertical and ground plane antennas

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

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

Schematic diagram of the VLA 200 power amplifier by RM Italy

VHF Power amplifier VLA 200 english manual