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Notes on W3EDP Antenna by M1KTA

Open-Wire/Twinlead Antenna Switch

This small, light weight digital SWR and power meter uses an Atmel AVR Butterfly demo board and a Stockton type directional coupler.

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

A 40 meter rig with SSB and CW operating modes. This is a low power QRP rig with up to 6 watts CW or PEP output.

Paddles by Jim Nestor WK8G/2

Roger, G3XBM, shares his extensive experience in **QRP** (low-power) amateur radio operation, detailing various aspects of transmitting with minimal power. The resource provides insights into VLF (Very Low Frequency) reception techniques and the construction of simple **crystal radio sets**, reflecting a foundational approach to radio experimentation. It includes links to external resources covering QRP clubs, online receivers, manufacturers, and technical references, offering a curated collection for enthusiasts. His page serves as a hub for those interested in the challenges and rewards of QRP, often comparing the efficacy of different low-power setups. The practical application extends to understanding basic radio principles through hands-on projects like crystal sets, which G3XBM has explored. The collected links provide a starting point for further research into specific QRP equipment or operating practices, drawing on G3XBM's long-standing engagement with the QRP community.

Maker of QRP Kits, QRP CW receiver and transmitters, audio CW Filters, antenna tuners, dummy loads, and morse code practice oscillator

Optimizing performances of the end-fed antennas QRP quarterly article

QRP and other projects from Honolulu, HI

Crystal-controlled QRP tranceiver by F6BCU for 80 meters band 1W output

Optimization tests of the W3EDP multi-band HF wire antenna a popular aerial among QRP enthusiasts because it is light weight and cheap.

A resurrection of some homebrew projects from our vintage years and the NorCal-sponsored project series in tribute to Doug DeMaw, W1FB

Information on ham radio including qrp, radio kits, Heathkit sw-717, Realisitic DX-160 and DX-302, and more.

Ham Radio Kits, including HF QRP SSB transceivers by EA3GCY

The MicroBeacon is the combination of a memory keyer and controllable RF attenuator.

GM47: Simple 30m Band QRP CW-Transceiver

Amateur Radio operator interested in mobile & emergency operations, with some portable QRP operations.

A homemade QRP Dummy Load with built-in RF detector

The SDR-908 is a software defined radio designed specifically for portable use, without the bother of being tethered to a PC or soundcard for the modulation/demodulation processing performed in this kind of radio.

Presents a QRP AM/CW transmitter project specifically designed for the 10-meter band, utilizing a crystal oscillator and a collector-modulated AM oscillator. The design employs a 2N2219(A) transistor in a Colpitts configuration, generating 100 to 350 mW of RF output power depending on the 9-18 Volt supply voltage and modulation depth. Frequency stability is maintained by a 28 MHz crystal, with fine-tuning possible via a Ct1 trimmer capacitor for approximately 1 kHz adjustment. The resource details the RF oscillator stage, implemented with a 2N2219 NPN transistor, emphasizing frequency stability and low power dissipation. It also covers the amplitude modulation stage, managed by a 2N2905 PNP transistor, which impresses audio information onto the carrier. Selective components (C3, C4, C7, C5) enhance voice frequencies within a +/- 5 kHz bandwidth, and modulation depth is controlled by R2 and R3. The project includes a 3-element L-type narrow bandpass filter (Ct3, L3, C10) to suppress harmonics and ensure a clean output signal. The project provides a complete schematic diagram, a comprehensive parts list including specific capacitor, resistor, and inductor values, and construction notes for the coils (L1, L2, L3). It also offers practical advice on enclosure requirements, suggesting an all-metal case or a PVC box with graphite paint for RF shielding. Operational parameters such as current draw (27mA@9V to 45mA@16V) and input impedance (50 Ohms) are specified, alongside guidance on antenna matching and the importance of a valid amateur radio license for 10-meter band operation.

An optimized QRP transceiver for 40 meters band

A small random wire antenna tune that can tune from 40 to 10 meters bands.

Paddles by Bill Nicolson, N2WF

The Micro24 is a ultra compact microsize QRP SSB transceiver for the 20 meters amateur radio band. This transceiver is so small that it fits into one hand.

QRP kits for Radio Amateurs

NN1G 30m 1W QRP transceiver by AA5TB

Color photos, schematic and diagrams for an article written by N2APB for Fall 2000 QRPp. Also the subject of a presentation made at the Pacificon QRP Forum in October 2000.An Integrated and Portable PSK Station for 80 & 20 without using a PC!

Small QRP Z-match project for max 10 W output by DL2LTO

This is the schematic of asolid-state 7 MHz QRP CW transmitter by VU2NAN

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

This article by Seabury Lyon, AA1MY describe how homebrew kits for amateur radio pourposes, in order to support wire antennas

A Home made QRP tuner for 10-40 meters

A simple low-power broadcast-type circuit, using a crystal oscillator integrated circuit and an a collector modulated AM oscillator

A small antenna tuner for 14 MHz

A circuit for a 5 milliwatts super QRP morse code transceiver by VE2ZAZ

Software Defined Radio Projects, HF Receivers and Transceivers projects by YU1LM/QRP

Comments received from QRP-L members concerning their experiences with GAP antennas.

Over 130 years after its inception, Morse Code remains a fundamental skill for many amateur radio operators, enabling efficient QRP operations, DXing, and contesting. This resource provides an in-depth look at the **Koch Method** of Morse training, a widely adopted technique that emphasizes high-speed character recognition from the outset. It details how this method can significantly accelerate proficiency, moving beyond traditional, slower learning approaches. The site also delves into the rich history of amateur radio, presenting articles such as "Radio on the Rio," which chronicles local ham activity in Socorro, New Mexico. Another piece, "The Russian Woodpecker," recounts the Cold War-era efforts of hams to counter Soviet over-the-horizon radar interference on the HF bands. Furthermore, the resource explores the fascinating intersection of ham radio and radio astronomy, highlighting the direct lineage between amateur experimentation and the development of modern radio telescopes like the **Very Large Array (VLA)**. It also includes an introduction to the 6-meter band, often called "The Magic Band," detailing its unique propagation characteristics and suitability for no-code licensees seeking long-distance contacts.

The resource details the construction of a homebrew 50-watt FET amplifier, based on Don W6JL's _QST Homebrew contest_-winning design from 2009. It functions as an afterburner for QRP transceivers, providing a **12dB** power lift. The amplifier utilizes IRFZ24N FETs and covers the 80, 40, 30, and 20-meter bands, with the 20m LPF extending to 17m. Key technical aspects include an FT37-43 transformer for the input network, a relay-switched 3dB pad for lower bands controlled by an _Arduino Nano_, and an RF-actuated T/R switch. The LPF board integrates four relay-switched filters rated for 50 watts, using capacitors with a minimum 250VDC rating. Performance measurements indicate a power gain ranging from **4.4dB** on 20m to 8.1dB on 80m, with a required drive power of approximately 5 watts. The article also discusses thermal management, current limiting considerations, and component sourcing.

A hombrew QRP transceiver for 40 meter band with many pictures, circuit and sound recording of some QSOs made with this Rig consisting of 5 transistor and one chip.

A Simple and Flexible Tuner for QRP Craig LaBarge, WB3GCK

Demonstrates the operational status and reception reports for the SK6RUD/SA6RR QRPP beacons, which transmit on 478.9 kHz, 1995 kHz, 10.131 MHz, and 40.673 MHz. These beacons utilize extremely low power, with the 630-meter beacon operating at approximately 0.1 watt ERP into an L-antenna, showcasing the potential for long-distance contacts under favorable propagation conditions. The site details the specific frequencies and antenna types employed, such as a vertical at 500 kHz and a 1/4 vertical for higher bands. The resource compiles over 10,530 reception reports from amateur radio operators worldwide, logging details such as date, time, band, RST signal report, locator, distance, and receiver setup. Notable long-distance reports include a 500 kHz reception by AA1A-Dave from 5832 km in 2008 and a 10.133 MHz reception by ZL2FT-Jason from 17680 km in 2010, illustrating the global reach of these low-power transmissions. Each log entry provides specific equipment used by the reporting station, including transceivers like the Yaesu FT817, ICOM IC-7300, and various antenna configurations such as coaxial mag loops, inverted Ls, and end-fed wires. The primary objective of the SK6RUD beacons is to challenge conventional notions of power requirements for effective two-way communication, proving that contacts over significant distances are achievable with minimal output. The site also includes a submission form for new reception reports, fostering community engagement and continuous data collection on propagation phenomena across different bands. The detailed logs offer practical insights into real-world propagation characteristics and the efficacy of QRPP operations.

LnR Precision Inc. is a North Carolina based company that specializes in Par EndFedz amateur radio antennas and MantiZ QRP Transceivers. Their most popular products include End-Fed QRP portable antennas and HF FX Series QRP Transceivers.

An Homebrew 10 Meter transceiver

Transverters-Store is a online shop for low cost transverter boards, but also QRP transceivers, Active antennas, RF bridge and probes, Mic equalizers and other amateur radio accessories

Photos from around the world of perhaps the most famous QRP project ever created. Vintage 1970's and newer versions of the Tuna Tin Two are featured.

Showcasing a range of precision-engineered Morse code paddles, UR5CDX emphasizes craftsmanship in both dual and single paddle designs. Each key, such as the _Eridan MX_ or _CT 73 MB_, is engineered for optimal performance, catering specifically to the needs of CW operators. The paddles are not merely tools; they reflect the artistry inherent in ham radio equipment, with options for personalization like _Callsign engraving_ and _3D nameplate_ tags. The commitment to quality is evident in the materials used and the precision of the mechanics, ensuring reliable operation during contests or casual QSOs. Yury, UR5CDX, also engages with the community, sharing insights on the manufacturing process and the impact of current events on production timelines, fostering camaraderie among operators who appreciate the nuances of Morse code communication.

Designing and constructing portable wire antennas for HF operations, this resource explores several configurations including the _foldback dipole_ for space-constrained setups and an inductively shortened dual-band dipole for 20m and 40m. It details the calculation of inductance for shortened elements, providing a Visual Basic 6.0 program screenshot that illustrates determining coil parameters like turns and length for a **25.5 uH** inductor. The document emphasizes practical considerations such as adjusting wire lengths for optimal SWR, noting that a dual-band dipole achieved SWR below 2:1 on both 20m and 40m, with careful adjustment bringing it under 1.5:1. Further, the resource describes a half-wave antenna matched with a coaxial stub, a method often referred to as the _Fuchskreis_ in German amateur radio circles, to transform the high feedpoint impedance to 50 Ohms. This monoband solution, for a 20m application, uses a stub length of **2.98m** (0.216 lambda multiplied by coax velocity factor) and a shorted stub of approximately 48cm. The coaxial stub design is highlighted for its resilience to ground proximity, allowing it to be rolled up or laid on the ground with minimal SWR impact, making it highly suitable for portable QRP operations.