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Mitigating impulse-type noise, a common challenge in the **HF radio spectrum**, often requires specialized processing before the signal reaches the transceiver's receiver stages. The NR-1 addresses this by functioning as an RF interference removal device, specifically a noise blanker, targeting transient noise sources. Its operational range extends from 1.6 MHz to beyond 70 MHz, making it suitable for various amateur radio bands and general shortwave listening applications. Unlike QRM eliminators or X-phasers, the NR-1 does not require a separate noise antenna for its operation, simplifying its integration into existing station setups. The device's design focuses on wideband performance, allowing its use both within and outside the allocated amateur radio frequencies. Documentation detailing its operation is available, providing insights into its technical specifications and deployment. This unit is a hardware product, conceptualized and implemented by SV3ORA.

For my SOTA activities, i recently bought a QRP transceiver QRP SW-3B, which is a three-band QRP CW only for 40/30/20 m. So, i needed an antenna that would allow to use these 3 bands in SOTA portable activity. Already having some experience with the EFHW antenna, i decided to build one for 40/30/20m.

The PAC-12 Antenna, a multi-band portable vertical, is meticulously detailed in this construction article by James Bennett, _KA5DVS_. The design emphasizes ease of homebrewing using readily available components from local hardware stores, including replaceable loading coils. It outlines the preparation of the 72-inch telescoping whip (originally from Radio Shack, with an alternate source now provided by _Pacific Antenna_), the construction of the loading coils from PVC risers, and the fabrication of the aluminum rod base sections. Specific instructions cover threading aluminum rod with a _1/4-20 threading die_ and assembling the feedpoint insulator with a BNC connector, along with recommendations for radial deployment. KA5DVS, an avid traveler and QRP enthusiast, developed the PAC-12 to address the bulkiness of random wire setups and the limitations of commercial portable antennas like the Outbacker or SuperAntennas MP1. His goal was a lightweight, packable antenna that disassembles into 12-inch sections, achieving an assembled length of approximately 8 feet. The design strategically places the loading coil away from the base for improved efficiency. The PAC-12 notably placed first in efficiency compared to a quarter-wavelength wire vertical at the HFPack antenna shootout during the Pacificon conference in October 2001, demonstrating its practical performance for field operations. Appendix C showcases various _NJQRP Club_ members' PAC-12 constructions, including a 20m beam made with multiple PAC-12 elements.

This is an uncommon loop antenna, hombrewed without the small feeding loop. With small spare parts is possible to build a loop antenna tuner for portable usage tha can ben used with common HF QRP transceivers

This article introduces an Arduino-based QRP CW Transceiver designed for lower HF bands. The journey begins with the Wotduino, evolving from a keyer to a multi-mode beacon. The development includes a QRP transmitter and culminates in a receiver inspired by Roy Lewallen design. The transceiver, controlled through a control bus features a signal path, modulation, filtering, and adjustable frequency settings. Despite initial testing intentions, successful QSOs on 80 and 40 meters showcase its functional capabilities.

The 1 watt 20 meter QRP transmitter with VXO. This is a nice QRP transmitter that can be used in combination of one of the simple receivers.

Optimizing the cable connections for cat control and audio input output by implementing the digirig mobile. A small audio and rig control interface, with a single USB cable supports most QRP radios requiring external audio and CAT control facilities

RF Power measurement using a DVM, RF Power measurement using an RF detector, RF Power measurement using an Oscilloscope and using a Spectrum Analyzer

Revision of the Cigarette Pack 14MHz SSB QRP Micro-Transceiver

Personal web site by N9SKN about portable QRP operations with pictures of several portable setups and antenna solutions.

The UniBalun is a PCB for building a lightweight antenna transformer (Balun) or impedance converter (UnUn) for low power radios. By soldering jumpers and a toroid core, you can create a 1:1, 1:4 Balun or 1:49, 1:9 UnUn. The latest revision (1.2) includes improved pads and supports both BNC and SMA connectors. Build instructions are available for German speakers.

A nice QRP, EME, satellites, VHF DX, Amateur radio blog by Lars Petersen OZ1BXM

This project details the creation of a portable GoBox housing an IC705, Windows 11 PC, and Bluetooth microphone. The robust setup, enclosed in a weatherproof Hofbauer Explorer Case, ensures stability and functionality for QRP and emergency radio activities. The aluminum-mounted devices minimize RF interference, and a built-in LifePO4 battery powers the 10.1 TFT touch LED monitor, providing approximately 12 hours of use in receive mode. With a focus on grab-and-go versatility, this GoBox stands as an efficient solution for outdoor ham radio operations.

The MiniPA Linear Amplifier for HF page discusses the popularity of QRP for HF among ham radio operators, such as those using the Yaesu FT818 or low power SDR transceivers. It explores the use of cheap kits from eBay or Chinese suppliers to build a 70-100W SSB amplifier using IRF530 MOSFET transistors. The article provides a review of the MiniPA design, including its features, components, and assembly process. It also highlights the importance of using a heatsink and forced air cooling for optimal performance. This page is useful for hams looking to enhance their HF rig with a budget-friendly amplifier.

A medium power End Fed Half Wave Antenna coupler, specifically tuned to the QRP frequency of 7030 kHz. Constructed from coil stock and capacitors, it achieves an impedance ratio of 64:1. The coupler has proven effective for power ranges from 2 to 100 Watts on the 40m band.

This page describes a printed circuit board that you may use to build a QRP keyer.

A Home made antenna tuner for QRP transceivers. This small tuner is the ideal for portable operations with random length wires or whenever you have not a resonant antenna.

1-watt 17-meter cw transmitter that was originally done about 10 years ago as a club project for RAMS, the Radio Amateur Megacycle Society. It uses a VXO, rather novel at the time. It also uses a bandpass filter at the output rather than the usual lowpass

Original HF magnetic loop antenna designed by the author to work in conjunction with QRP transceivers like the FT-817 in portable operations. In this configuration the loop can operate from 30 to 10 meters. Using a two spires radiator of the same diameter it also covers 40 meters.

Tutorial, How to call CQ as an HF QRP station in SSB/Phone. Calling CQ Basics, Calling CQ QRP or Portable

a 20M quarter-wave vertical antenna with a 6m telescopic mast, 1:1 balun, and spiral-wound driven element. Designed for QRP at 14.285 MHz, the antenna’s performance exceeded expectations, delivering low SWR and surprisingly quiet reception. Initial testing yielded successful contacts with European stations and EC1KR, showcasing its effectiveness. Compact and easy to deploy, the antenna promises to be an excellent portable solution for future hilltop operations.

Learn how to build a QRP digital transceiver with Arduino, based on a project by Burkhard Kainka. This article covers the development process, including the source code, modifications made, and the addition of an OLED display for a more professional look. Discover the inner workings of the transceiver, from the receiver to the oscillator, and how components like the CD2003 are utilized. Explore the schematic design, the use of a PLL module Si5351A controlled by Arduino nano, and more. Ideal for hams looking to create their own digital transceiver for amateur radio operations.

Notes, hints and tips on starting with morse code, how to approach learning the code, how and when to get on the air, learning and using abreviations, common Q-Codes and a sample morse code QSO.

Arduino Digital Transceiver (ADX) is a low-cost HF transceiver for digital modes. This Arduino-based project, inspired by QDX, features four bands, including 80m and 20m, supporting FT8, FT4, JS8call, and WSPR. Designed for simplicity and affordability, it uses an Arduino Nano, SI5351 module, and CD2003GP receiver. The ADX project emphasizes easy procurement, construction, setup, and operation, making it an accessible option for QRP enthusiasts. The firmware update enhances functionality, including CAT control support.

This article explores the conventional wisdom about antenna height in amateur radio operations, challenging the common belief that "higher is always better." Through practical examples and computer modeling, it examines how low-height antennas like Beverage antennas, VP2E, and End-Fed Half Wave (EFHW) configurations can perform effectively in various scenarios. The analysis includes radiation patterns and efficiency considerations for antennas at different heights, particularly focusing on portable operations. The article demonstrates that while height affects antenna performance, lower installations can still provide practical and efficient solutions for specific applications, especially in portable and QRP operations.

Newsletter article detailing the step-by-step construction of a 2m Hentenna using copper pipes, including user experiences and performance evaluations

Early pictures and presetation of the Icom the IC-705, new all bands all modes QRP transceiver introduced at Tokio HamFair on August 31st September 1st 2019.

CW Morse Nano QRP and Micro Keys. CW Morse PCB Keys. Morse Keyers

The QMX+ Transceiver Kit from QRP Labs is a high-performance, feature-packed 160-6m 5W transceiver designed for hams. This multi-mode kit includes embedded SDR, USB sound card, CAT control, synthesized VFO, RTC, and optional internal GPS. It can be used in CW, digital, and SSB modes, with standalone CW operation, digi mode via USB to PC, or SSB operation. The kit offers standalone beacon functionality and shares firmware with the QMX model. With an optional enclosure, battery-backed RTC, and GPS, the QMX+ is versatile and easy to build, making it ideal for ham radio operators looking for a customizable transceiver kit.

The SW-3B is a Three-band CW QRP transceiver, Weight 180g, output power 5W at 12v, 2W at 9v, works on 40 30 and 20 meters band

This PDF article introduces a series of dual-tuned bandpass filters designed for input tuning in amateur band receivers. Developed by Stefen Niewiadomski, these filters feature 50-ohm input/output impedance and can be cascaded for improved roll-off outside the passband. The designs use readily available TOKO coils, with taps on the tuned winding for matching input circuits with impedances around 1k ohm. The inductors are core-tuned, with average inductance values provided for easier matching to other inductors.

QRP is a Q-code originally meaning reduce power, but now has come to mean operating a radio that outputs 5 watts or less for CW or 10 watts for SSB.

Paul McMahon presents a compact VSWR meter designed for QRP portable use, ideal for SOTA operations with rigs like the FT817. The device, constructed from readily available components, employs a simple resistive bridge for wideband performance from 1.8MHz to 52MHz, with diminishing accuracy at higher frequencies. Key features include no need for external power, simple calibration, and operation with low power levels. The design, detailed with parts lists, schematics, and construction guidelines, ensures a 2:1 worst-case VSWR to protect transceivers during antenna matching. Calibration points are set for accurate VSWR readings at various loads.

A portable QRP setup based on 20/30/40m QRP CW-only SW-3B transceiver, 2500mAh 5C LiPo battery (147g), Hands Free Nanokeyer

A single coil Z-Match. This QRP version by G3WQW, using a T130-2 toroidal inductor and polyvaricon variable capacitors was published in Sprat 84.

An easy to build 6 watts SSB transceiver for 14MHz. BITX is an easily assembled transceiver for the beginner with very clean performance. Using ordinary electronic components and improvising where specific components like toroids are not available, It has a minimum number of coils to be wound.

This innovative antenna tuning unit (ATU) enables QRP operators to match their antennas without transmitting RF signals. Using a noise bridge technique instead of traditional transmit-and-tune methods, it achieves truly silent operation. The design incorporates an L-match network with switched inductors and variable capacitor, handling impedance matching from 3-30MHz. Operating from a 9V battery, it includes a built-in RF power meter and dummy load for QRP transmitter testing. The compact unit is particularly suitable for portable operations where minimal RF emissions during tuning are desired.

This article details a ham radio operator’s experience setting up HF antennas in an antenna-restricted community. Initially using an AEA Isoloop magnetic loop for QRP PSK, the author later built an attic antenna system, including dipoles for multiple HF bands and a slinky dipole for 40 meters. The setup allowed for operation on six bands with acceptable VSWR. Despite space constraints and some compromises, performance was effective. The article highlights practical strategies, emphasizing experimentation and antenna modeling for optimizing performance in limited-space environments. A valuable guide for ham radio operators facing similar restrictions.

A Magnetic Loop Controller project details the construction and operation of an automatic tuning system for magnetic loop antennas, which are resonant circuits using an oversized inductor and an adjustable capacitor. The system employs a stepper motor to precisely adjust the variable capacitor, maintaining optimal resonance across the HF bands. It integrates with various transceivers, including _Icom_, _Kenwood_, and _Yaesu_ models, by monitoring the VFO frequency and adjusting the loop's tuning accordingly. The project provides comprehensive building instructions, a PowerPoint-style presentation, and the full source code for the controller's firmware, enabling hams to replicate and customize the design. The controller's firmware offers diverse functionality, including automatic frequency tracking, manual tuning, and SWR monitoring, significantly enhancing the operational efficiency of magnetic loop antennas, particularly for QRP and portable operations. The design emphasizes accurate capacitor positioning, crucial for achieving low SWR and maximum radiated power. Comparisons with manual tuning methods highlight the benefits of real-time adjustment, especially when operating across different bands or making frequent QSYs. The project's detailed documentation and available source code facilitate experimentation and modification by advanced builders, allowing for tailored performance characteristics.

In the pursuit of an affordable matching and SWR indication solution for the Pixie-based transceiver system this T-Tuner and SWR bridge unit, while not groundbreaking, proves to be a cost-effective performer. With real-world impedance testing yielding a worst-case loss below 0.9 dB, the unit efficiently matches all bands on 80 M to 10 M ham bands, making it a valuable addition to the QRP system.

The ICOM IC-705 remains a standout portable transceiver after 3.5 years of use. Its unmatched feature set includes multi-band/mode support, built-in WiFi, GPS, remote operation, and excellent third-party app integration, making it versatile and user-friendly. Despite competition like the Elecraft KX3 and Yaesu FT818, the IC-705 excels in flexibility, durability, and ease of use. Whether for QRP operations, digital modes, or SSB, it delivers exceptional performance in diverse settings, reaffirming its status as the best portable transceiver on the market.

There are few equipment for the 4m band, so to get on the band it could be necessary to design and build a simple transverter.

JBOT stands for Just a Bunch of Transistors. It is a simple, stable and easy to build 5 watts linear amplifier build out of a bunch of ordinary low power NPN transistors.

Antennas for low-power operation resemble those for 100W use. Minor adjustments, like capacitor voltage ratings, may apply, but basic principles persist. Portable antennas, notably Backpack Antennas for weight-conscious setups, hold relevance beyond QRP. While some antennas function acceptably at higher power, efficiency issues arise at QRP levels. Testing antennas at 100W exposes weaknesses, particularly in tuners, crucial for efficient QRP operation.

This page by Lajos Hoss, HA8HL, provides a detailed guide on how to build a simple direct receiver using FT8QRP CAT control support. The author shares his experience in making QSOs with FT8, WSPR, and JT65 modes during the Covid-19 lockdown. Modifications to the VFO, transmitter design using BD329 transistor Class A amplifier, and the challenges faced in achieving clean output signals within legal limits. This project is interesting for those hams that are interested in experimenting with DIY transmitter projects and understanding CAT control support for various amateur radio modes.

This project delves into the development of a compact WSPR beacon, building on earlier experiences with weak-signal modes. Inspired by QRP Labs kits and modified open source designs, it integrates a Si5351 frequency generator, GPS module, and class E PA for efficient operation. Extensive optimizations—addressing drift, heat management, and power stability culminated in a portable, serviceable device. The beacon offers insights into propagation while minimizing reliance on main station equipment. Lessons learned highlight the importance of careful component selection and iterative design improvements for robust amateur radio experimentation.

Learn how to build your own QRPGuys DS-1 40-10m short vertical antenna for ham radio operators. This page provides detailed instructions on constructing this antenna, which covers the 40 to 10-meter bands. Whether you're a beginner looking to get started with antenna building or an experienced ham radio operator looking for a new project, this resource is useful for anyone interested in DIY antennas for portable or QRP operations.

The QRP Cluster provides a dedicated platform for _QRP_ (low power) amateur radio operators to self-spot their on-air activity. This web-based service allows users to post real-time information about their current operating frequency, modulation mode, equipment used, and transmit power. It facilitates QRP-to-QRP contacts and helps other low-power stations locate active QRP signals across various bands. Unlike general DX clusters, the QRP Cluster focuses exclusively on low-power operations, fostering a community for QRP enthusiasts. It enables operators to share details such as **5 watts** or less output, often specifying antenna types or unique portable setups. The platform supports the discovery of QRP stations for casual QSOs, contests, and award hunting, enhancing visibility for stations that might otherwise be overlooked on higher-power clusters.

LZ1AQ describes a versatile QRP antenna tuner that switches between Pi and Tee configurations with a single toggle. Using two variable capacitors and a seven-switch stepped inductor providing 128 increments (0.16 to 18.7 uH), this compact design handles 3.5 to 28 MHz with excellent matching range. The Pi mode works best for certain impedances while Tee mode proves more universal, matching loads the Pi cannot. Built in a plastic enclosure using salvaged radio capacitors, the tuner operates reliably up to 100 watts with proper antennas, though it's optimized for QRP service with random wires.

DIY project of a QRP Balun. Using a high permeability ferrite rod and an old B&W dipole center insulator, he constructs a choke type balun for QRP use. The balun aims to create as much inductance as possible at HF, offering a high impedance to common mode currents