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The project details a DIY SWR/Wattmeter designed around an _Arduino Uno_ shield, providing capabilities to measure RF power from 2 to **200 watts** and Standing Wave Ratio (SWR) for HF amateur radio bands. This construction features a compact design, integrating the measurement circuitry directly onto a custom PCB that interfaces with the Arduino Uno microcontroller. Key components include a directional coupler for sensing forward and reflected power, precision rectifiers, and analog-to-digital conversion for processing RF signals. The Arduino firmware handles calibration, calculations, and displays the results on an integrated LCD, offering real-time feedback on antenna system performance. The design prioritizes simplicity for homebrewers. Performance specifications indicate accurate readings within the **2-200W** power range, suitable for typical QRP to medium-power HF operations. The project provides schematics and a basic overview of the software logic.

WSJT-X implements communication protocols including FST4, FST4W, FT4, FT8, JT4, JT9, JT65, Q65, MSK144, WSPR, and Echo. These modes facilitate reliable, confirmed QSOs under extreme weak-signal conditions. JT4, JT9, and JT65 utilize a nearly identical message structure and source encoding, employing timed **60-second** transmit/receive sequences synchronized with UTC. JT4 and JT65 are designed for EME on VHF/UHF/microwave bands, while JT9 is optimized for MF and HF, offering **2 dB** greater sensitivity than JT65 with less than 10% of its bandwidth. Q65 provides submodes with varying T/R sequence lengths and tone spacings, suitable for EME, ionospheric scatter, and weak signal operations on VHF, UHF, and microwave. FT4 and FT8 operate with T/R cycles of 7.5 and 15 seconds, respectively, supporting enhanced message formats for nonstandard callsigns and contest operations. MSK144 is engineered for Meteor Scatter on VHF bands. FST4 and FST4W target LF and MF bands, achieving fundamental sensitivities near theoretical limits for information throughput; FST4 is for two-way QSOs, and FST4W for quasi-beacon WSPR-style transmissions, without requiring the strict time synchronization of protocols like _EbNaut_. WSPR mode enables propagation path probing via low-power transmissions, incorporating programmable band-hopping. The **WSJT-X 2.7** General Availability release introduces the QMAP program, Q65 Pileup, SuperFox mode, a Hamlib update option, and a Message System. SuperFox mode transmits simultaneously to up to 9 Hounds with a constant envelope waveform, providing approximately +10 dB system gain compared to older Fox-and-Hound operations. _WSJT-X 2.7_ for _Windows_ platforms includes _MAP65 3.0_, a wideband polarization-matching tool for EME. The **WSJT-X 3.0.0-rc1** candidate release represents a major revision with new features, some ported from _WSJT-X Improved_. This software is available for _Windows 7_ and later (32-bit/64-bit), various Linux distributions (Debian, Ubuntu, Fedora, RedHat, Raspberry Pi OS), and macOS (10.13 through 15). DXZone Focus: Weak Signal | Digital Modes | WSJT-X | Windows

Over 30 distinct shortwave (SW) receiver models are reviewed, offering insights into their performance, features, and user experiences. These evaluations, contributed by readers of the Usenet newsgroup **Rec.radio.shortwave**, cover a wide array of portable and tabletop radios, including popular units like the Grundig YB-400, Sony ICF-SW77, and various Realistic DX series models. Each review details aspects such as frequency range, tuning steps, SSB functionality, antenna performance, and construction quality, often comparing them to other receivers or ham transceivers like the Icom 725. For instance, the Grundig YB-400 review highlights its 144-30000 kHz AM/SSB coverage, direct keypad entry, and 40 station memories, noting its useful narrow bandwidth and tone switch for adjacent signal separation. It also discusses the **SSB mode** stability and the limitations of its 1 kHz frequency resolution for precise zero-beating. The review further details antenna performance, including the effectiveness of the built-in whip, the provided 7m reel antenna, and the potential for overload with larger outdoor antennas. Other reviews delve into specific issues, such as the Sony ICF-SW77's frequency display inaccuracies and timer malfunctions, or the Realistic DX-342's compact size and surprisingly good MW DXing capabilities despite its analog tuning. The collection provides practical, user-generated feedback on sensitivity, selectivity, audio quality, and ergonomic features, helping shortwave listeners understand the real-world performance and quirks of these receivers.

CW Skimmer 2.1 employs a high-sensitivity CW decoding algorithm based on Bayesian statistics, enabling simultaneous decoding of up to 700 CW signals within a receiver's passband on a 3-GHz P4 system when paired with a wideband receiver. The software features a fast waterfall display with sufficient resolution for visual Morse Code interpretation, automatically extracting and labeling callsigns on the waterfall traces. Extracted callsigns are exported as DX cluster spots via an integrated Telnet cluster server. The application includes a DSP processor with a noise blanker, AGC, and a variable-bandwidth CW filter, alongside an I/Q Recorder and player. It supports both 3 kHz radio passbands and wideband SDR receivers like SoftRock, RF Space SDR-IQ/SDR-14, SRL QuickSilver (QS1R), HPSDR Mercury, and Microtelecom Perseus. System requirements specify Windows XP/7/8/10 (32-bit or 64-bit), a Pentium-4 2.5 GHz for wideband operation or 1 GHz for 3-kHz radios, a COM port for CAT control, and a stereo sound card supporting 48 kHz sampling. It integrates with Elecraft KX3, Icom IC-7300/IC-7610, and Flex 6000 series radios, with documentation available for various setup configurations.

What is NVIS Near Vertical Incident Skywave. This article on NVIS (Near Vertical Incidence Skywave) explores its role in short-range HF communication, covering 0-200 miles. NVIS utilizes antennas with high radiation angles and frequencies below the ionospheric critical frequency to achieve reliable local contact. He details optimal antennas, like low dipoles, and practical tips for maximizing NVIS performance, emphasizing its advantages such as reduced noise and independent operation without repeaters. However, challenges include frequency sensitivity and the need for appropriate antenna setups at both ends for effective communication.

Argo, developed by I2PHD and IK2CZL, functions as a specialized freeware viewer for various weak signal modes, specifically MTHELL, Slow CW, QRSS, and DFCW. It processes audio input to visualize and decode these extremely low-speed transmissions, which are often imperceptible to the human ear. The software's capabilities extend to EME (Earth-Moon-Earth) operations, where its sensitivity to weak signals is particularly advantageous for detecting faint lunar reflections. The application provides a visual representation of the received signals, allowing operators to discern patterns and decode information from signals buried deep within the noise floor. Its design focuses on extracting data from signals with very narrow bandwidths and long integration times, characteristic of QRSS and similar modes. This tool is distinctively useful for experimenters and DXers engaged in challenging weak signal communication, offering a dedicated platform for modes not typically supported by general-purpose digital mode software. Its specialized focus on _Slow CW_ and _MTHELL_ makes it a niche but effective utility for specific operating scenarios.

These devices are called Traps, but they are actually more like frequency sensitive switches. They are parallel resonant, high Q, tuned circuits which provide a very high impedance at their frequency of resonance.

Includes the PDF file of the General Class study guide by Dan Romanchik KB6NU free to download.

A Portable Low Frequency Antenna Analyzer, For those of us who like to play with antennas on the ham bands, one of the handiest tools to have around the shack is an "antenna analyzer". These gadgets combine a signal generator and standing-wave ratio (SWR) sensor in a small battery-powered unit.

On 23cm the best way to obtain a good RX-sensitivity is to use a GaAs-FET in the front-end, since these devices show very low noise figures.

A sensitive RF probe is very useful in a situation where an oscilloscope is not available

Demonstrates CW Decoder Logic, a freeware application for Windows Vista SP2, 7, 8, and 10, designed to decode Morse code signals. The software incorporates an optimized 80 Hz DSP filter, enabling reception of CW signals across a speed range of 5 to 60 WPM. Key features include automatic signal tracking within a 3 KHz range, real-time speed detection, and an auto squelch function, enhancing decoder sensitivity and accuracy. The application provides station selection directly on a waterfall display and includes a "Tips" feature for word annotations. It supports sending decoded text to external logging software via UDP protocol, with a logger source code example provided for developers. Configuration options allow users to set speed limitations and customize interface elements. Released initially on October 17, 2016, with subsequent updates, the program requires Microsoft .NET Framework 4.5 or higher. Changelogs detail improvements such as increased program stability, code optimizations for speed, and fixes for display issues across different Windows versions.

Constructing a Lindenblad antenna for 137MHz NOAA satellite reception involves specific design considerations for optimal performance. The resource details the use of 4mm galvanised steel fencing wire, 300-ohm television ribbon cable, and wood/plastic components for the antenna structure. Key dimensions for a 137.58MHz-resonant antenna are provided, derived from the ARRL Satellite Handbook, specifying s, l, w, and d as 42, 926, 893, and 654mm respectively. The antenna is designed for Right Hand Circularly Polarised (RHCP) signals, requiring the four folded dipole elements to be tilted clockwise by 30 degrees. A significant aspect covered is impedance matching between the antenna's 75-ohm impedance and a typical 50-ohm receiver input. A twelfth-wave matching transformer, constructed from 117mm sections of 50-ohm RG-58 and 75-ohm RG-59 coax with a 0.66 velocity factor, is described. The article also addresses coaxial cable and connector selection, recommending 75-ohm Type-N connectors for RG-6 cable in professional setups and F56/F59 connectors for general use, while strongly advising against PL-259/SO-259 connectors for VHF. Strategies for mitigating Radio Frequency Interference (RFI) are discussed, including antenna placement to shield from local TV transmitters and the use of commercial or DIY band-pass filters, such as cavity resonators or helical notch filters, along with ferrite chokes on coaxial cables. Antenna orientation is explored, noting the Lindenblad's 'cone of silence' directly overhead and its maximized sensitivity towards the horizon. An experimental vertical tilt of 90 degrees is presented as a method to improve overhead reception and reduce interference from strong horizontal signals, particularly relevant in high RFI environments like the Siding Spring Observatory site.

The RigPix database entry provides a comprehensive technical overview of the Icom IC-746 amateur HF/VHF transceiver, detailing its operational parameters and physical characteristics. It specifies the transmit frequency ranges across 10-160 meters plus WARC bands, 50-54 MHz, and 144-146/148 MHz, alongside receive coverage from 0.03-60 MHz and 108-174 MHz. The resource outlines supported modes including AM, FM, SSB, CW, and RTTY, noting a tuning step resolution down to 1 Hz and a frequency stability of ±5 ppm. Key electrical specifications are presented, such as a 13.8 VDC power supply requirement, current drain figures for RX (1.8-2 A) and TX (Max 20 A), and RF output power ranging from 5-40 W for AM and 5-100 W for FM, SSB (PEP), and CW. The entry details the triple conversion superheterodyne receiver system, listing IF frequencies at 69.01 MHz, 9.01 MHz, and 455 KHz, along with sensitivity ratings for various modes and bands. Transmitter section specifics include modulation systems and spurious emission levels. Additional features like a built-in auto ATU, electronic keyer, simple spectrum scope, DSP, and CI-V computer control are noted. The page also lists related documents, modifications, and an extensive array of optional accessories, including various filters, microphones, and external tuners, providing a complete profile of the IC-746.

Presents the design and construction of the OK2FJ Bigatas, a portable, automatically tuned vertical antenna covering 80 through 10 meters. It details two distinct control systems: one utilizing BCD band data from Yaesu FT-857/897 transceivers, and another employing voltage level sensing for the Yaesu FT-817. The resource provides specific instructions for building the antenna's radiating element, loading coil with switchable taps, and the control circuitry, emphasizing the use of readily available components. The article outlines the physical construction of the antenna, including the use of duralumin tubes for the radiator and a PVC tube for the coil form. It specifies coil winding details, tap points, and the integration of radial wires for ground plane operation. The control electronics section provides schematics and component lists for both the BCD decoder (using a 74LS42 IC) and the voltage comparator (using an _LM3914_ bargraph driver), enabling rapid, automatic band switching without the minute-long tuning delays common in other systems. Crucially, the antenna achieves rapid band changes, with typical SWR values centered on common operating segments, such as **3.7 MHz** for 80m SSB. It also discusses modifications for CW operation on 80m and the trade-offs between antenna efficiency and full-range automatic tuning on higher HF bands, where manual adjustment of radiator length is suggested for optimal performance on 15m, 12m, and 10m. The resource includes construction photos and a discussion of cable requirements for reliable operation.

The ICOM IC-7300 is a cutting-edge HF transceiver that has garnered significant attention since its release. This review, published by ARRL in QST, provides an in-depth analysis of its features, performance, and usability. The IC-7300 is known for its direct sampling technology, which enhances its sensitivity and selectivity, making it a favorite among amateur radio operators. The review covers various aspects, including the user interface, audio quality, and overall operational capabilities, providing valuable insights for both new and experienced hams. In addition to its technical specifications, the review discusses the IC-7300's performance in real-world scenarios, such as DXing and contesting. It highlights the transceiver's ability to handle weak signals and its versatility across different modes. The review serves as a helpful guide for those considering the IC-7300 for their station, offering a balanced perspective on its strengths and potential drawbacks. Overall, this review is an essential resource for anyone interested in the ICOM IC-7300 and its place in the amateur radio landscape.

The Antenna Rotator Controller is unique in that it senses, displays, and controls to the earth's true magnetic field. The compass sensor, mounted in a waterproof enclosure, is attached to the mast and sends its signal to a microcontroller

Loop antennae have been used from ELF to UHF since the beginning of radiocommunications. At low frequencies, the main problem for loop antennae is to have enough sensitivity; the antenna being very small respect to the wavelength the collected energy is also small. To increase the output level the loop may be made resonant, so loosing it%u2019s intrinsic aperiodic characteristics.

The Icom IC-7300 is a popular HF transceiver among amateur radio operators, known for its advanced features and performance. This modification guide focuses on enabling extended transmission capabilities, specifically for MARS and CAP frequencies. The instructions are based on the work of PA2DB and include detailed steps for removing specific diodes to unlock additional frequency ranges. Before proceeding with the modification, users are advised to take necessary precautions, such as ensuring the radio is powered off and using ESD protection. The guide emphasizes the importance of using appropriate soldering techniques and tools to avoid damaging sensitive components. A video demonstration is also provided to assist users visually in performing the mod. While this modification can enhance the functionality of the IC-7300, it is crucial to note that it may void the warranty and should be undertaken at the operator's own risk. The guide serves as a valuable resource for those looking to expand their operating capabilities with this versatile transceiver.

A complete DIY Raspberry Pi Weather Station including software, capable to read wind speed, wind direction, rain gauge and with a temperature and humidity sensor along to a camera.

Radio frequency systems require robust protection against transient voltage events, which can severely damage sensitive equipment. This resource details a range of **RF surge protection** devices, including models with DC Pass, DC Block, Bias T, and Ultra Low PIM characteristics, designed to safeguard critical infrastructure. It also presents various RF filtering solutions and interconnect components, emphasizing their role in maintaining signal integrity and operational continuity across diverse applications. The site provides information on products engineered for both RF and data line protection, highlighting their utility in preventing downtime and equipment loss. Specific product categories encompass coaxial protectors, grounding items, and fiber optic solutions, indicating a broad scope of application from amateur radio installations to industrial and telecommunications networks. Furthermore, the resource mentions the availability of NOM-certified products and offers same-day shipping for many items, underscoring a commitment to rapid deployment and compliance with industry standards.

The HamCall.net database offers a detailed listing of amateur radio callsign divisions, organized by prefix, which is crucial for DXers and contesters to quickly identify the geographical origin of a station. Each entry includes a specific callsign prefix, the total count of callsigns registered under that prefix, and the associated DXCC country or entity, such as "AL9Z 43203 USA" or "3AOH9MM 237 MONACO." This structured data allows operators to rapidly ascertain the DXCC entity for a given callsign, aiding in QSL verification and award tracking. This information is particularly useful for confirming rare DX entities during contests or for logging contacts for awards like DXCC. For example, an operator hearing a "3Y0C" callsign can immediately identify it as Bouvet Island, a highly sought-after entity. The inclusion of callsign counts provides a sense of the activity level within each prefix, which can be helpful for anticipating pile-ups or assessing the likelihood of making a contact. The data presented reflects a snapshot of the HamCall database, offering practical insights into global amateur radio demographics.

Homebrewed handheld RF powermeters for various sensors by DL5NEG

Distributor of Sovtek, other current production vacuum tubes, and NOS tubes. Distributor of electronic parts for audio and musical instrument amplifiers. Manufacturer/ Distributor of Electro-harmonix effects.

Using a full-size antenna and a reasonably sensitive headphone, this simple switching mixer will produce an amazing abundance of signals on 80m.

This type of filter can be used in a Mode J satellite station (uplink on 2m, downlink on 70cm) to reduce the problem of the uplink signal desensing the receiver

Showcasing a specialized product line, Advanced Receiver Research presents a comprehensive catalog of **low noise preamplifiers** and microwave **Gunnplexers**. The offerings span a broad spectrum of radio frequencies, from VLF, LF, MF, and HF bands up through VHF, UHF, and microwave, catering to diverse applications including amateur radio, commercial installations, and military systems. Their product range includes mast-mount preamplifiers, inline attenuators, power dividers, and various coaxial components. My own experience with similar low-noise front ends for weak-signal work on 2 meters and 70 centimeters underscores the critical role such components play in maximizing receiver sensitivity, especially when chasing distant DX or engaging in EME. The detailed product descriptions and technical specifications provided on the site allow operators to select the optimal preamplifier for their specific band and noise figure requirements, essential for improving signal-to-noise ratio. The site also lists specialized products for unique applications like Nuclear Magnetic Resonance (NMR) and Studio Transmitter Links (STL), demonstrating a depth of engineering capability beyond typical amateur radio fare. This breadth of offerings, coupled with clear ordering and warranty information, positions Advanced Receiver Research as a key supplier for high-performance RF components.

A comeplete home made 600W LDMOS RF power amplifier. Settings can be made on a 7-inch touch screen, and on this screen you can see a lot of useful information during operation, such as output power, temperature, SWR, and so on. The power amplifier includes 2 MRF300 LDMOS FETs and several built-in sensors. The amplifier also contains several types of protection functions like too high current, too high swr, too high temperature, etc.

This resource details the four primary functions of a ground system: lightning energy dispersion, equipment safety, RF return path provision for end-fed antennas, and management of induced RF currents. It clarifies that a ground system's effectiveness varies depending on its specific function, noting that a good lightning ground might not be an effective RF ground. The content emphasizes that proper antenna system design, including baluns and appropriate feedline lengths, often negates the need for an RF station ground to mitigate common mode currents or RFI in the shack. The article quantifies lightning energy, stating its peak is in the dozens or hundreds of kilohertz, with damaging energy extending to hundreds of megahertz, and currents reaching thousands of amperes. It recommends solid, wide, smooth copper surfaces for ground leads to achieve low impedance across a wide frequency range. The author, W8JI, shares practical insights from his station, which includes two 300-ft towers and four 130-ft wire verticals, detailing his use of common point grounds and _DX Engineering RR-8 HD_ antenna switches for lightning protection without coaxial surge protectors. Specific examples of antenna systems prone to common mode current problems are listed, such as random wire antennas without proper feedline lengths and off-center fed dipoles. The text also explains how a ground screen or radial system can reduce local noise sensitivity for vertically polarized antennas by covering the lossy earth.

The Receiver Test Data resource is a detailed review database focusing on the performance metrics of various radio receivers. The methodology involves rigorous lab measurements, often adhering to standards such as the ARRL RMDR (Reciprocal Mixing Dynamic Range) and BDR (Blocking Dynamic Range). Specific test equipment and protocols are utilized to assess parameters like noise floor (dBm), AGC threshold (uV), and LO noise (dBc/Hz). For example, the _Icom IC-7300_ is evaluated with a noise floor of **-133 dBm** and an LO noise of **-141 dBc/Hz**, providing insights into its performance under different operational conditions. The resource includes a wide range of models, from the _Elecraft K3S_ to the _Yaesu FTdx-101D_, each tested for dynamic range, sensitivity, and selectivity. The data is sorted by key metrics such as third-order dynamic range and phase noise limitations, with RMDR values calculated by subtracting 27 dB from LO noise figures. This structured approach allows users to compare different receivers' capabilities, focusing on technical specifications and performance outcomes in various scenarios. DXZone Focus: Review Database | Lab Measurements | -133 dBm | ARRL RMDR

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.

Protecting amateur radio equipment from transient overvoltages requires robust lightning and surge protection, which is the focus of Electronic Specialty Products. The company provides various devices, including coaxial lightning arrestors for antenna feedlines and surge protectors for AC power lines and data circuits. These devices are engineered to divert high-energy surges, such as those caused by direct or indirect lightning strikes, away from sensitive transceivers, amplifiers, and computer components, thereby preventing catastrophic damage. Key products include the _Coaxial Lightning Protector_ series, designed for various impedance levels and frequency ranges up to 3 GHz, and the _AC Line Surge Protector_ for shack power distribution. Effective deployment of these protection devices can significantly reduce the risk of equipment failure and ensure operational continuity during severe weather. For instance, a properly installed coaxial arrestor can handle peak currents of **20 kA**, while AC line protectors offer clamping voltages typically below 400V. Comparing different models reveals varying levels of insertion loss and return loss, with some coaxial units exhibiting less than 0.1 dB loss at 500 MHz, making them suitable for high-performance HF and VHF/UHF operations. Integrating these components into a comprehensive grounding system is crucial for achieving maximum protection against both common-mode and differential-mode surges.

The North East Weak Signal Group (N.E.W.S.) website serves as the digital hub for an ARRL-affiliated regional club dedicated to _weak signal_ work across the VHF, UHF, and SHF spectrum, from 50 MHz up to light. It provides essential information for members and prospective enthusiasts, including the club's constitution and by-laws, details on officers and the board of directors, and a calendar of meetings and events. The site also features an application for membership, information on dues, and a membership roster, fostering a sense of community among its over 100 members. A significant feature of the site is its extensive archive of conference papers, including proceedings from the _Eastern VHF/UHF/Microwave Conference_ dating back to 2009. These papers cover a wide array of technical topics relevant to weak signal operations. The site also lists _50 MHz Beacons_ and _144 MHz and up Beacons_, along with links to other VHF and above resources, providing practical tools and knowledge for operators interested in pushing the boundaries of amateur radio communication.

The WaveNode WN-1 is a precision, full-featured Amateur Radio Station Monitoring System which now includes Audio Announcing for RF power, SWR, and DC monitoring using HF and UHF remote sensors.

Sensitivity of multi turn receiving loops William E. Payne, N4YWK

A view on TS570 sensitivity, a plot from 1.8 MHz to 60 MHz

WR1B review of the Kenwood TS-570D on QST Jan 1997

Details the construction of an **HF converter** designed by M1GEO, George Smart, specifically to extend the frequency range of the FunCube Dongle Pro (FCD) for amateur radio reception. The FCD natively covers 64 to 1,700 MHz, but this project enables reception from 0 Hz to 64 MHz by up-converting signals to the FCD's operational range. It employs a **double-balanced mixer** with a 100 MHz local oscillator (LO) to translate incoming HF signals; for instance, a 1 MHz signal appears at 101 MHz within the FCD's passband. The design incorporates a 7th-order Chebyshev low-pass filter with a 62 MHz cutoff frequency at the input to mitigate image frequencies, ensuring cleaner spectral presentation. George provides the schematic, PCB masks, and Gerber files for replication, noting that Far Circuits also offers PCBs. The resource includes test results for the low-pass filter and measurements of LO leakage, identifying -36.8 dBm at 100 MHz as a potential sensitivity concern. M1GEO discusses potential improvements, such as adjusting the mixer's LO drive, adding a balance pot, or incorporating a post-mixer high-pass filter to reduce LO breakthrough. Audio recordings from 40m and 17m demonstrate the converter's performance with WRplus SDR software.

Optimizing weak signal reception on the HF bands, particularly in the presence of strong local QRM, often necessitates specialized receiving antenna systems. This resource details the _HI-Z Antennas_ product line, focusing on phased vertical arrays designed for superior noise rejection and directivity. It covers components such as the 4-Square and 8-Element array controllers, which allow for rapid switching of receive patterns, and dedicated low-noise preamplifiers to improve system sensitivity. The site also presents various bandpass filters, crucial for mitigating out-of-band interference and enhancing the dynamic range of the receiver. The HI-Z systems are engineered to provide significant front-to-back and side rejection, often yielding **20-30 dB** of attenuation to unwanted signals, which is critical for DXing and contesting. Users can achieve a notable reduction in local noise, allowing for the discernment of signals that would otherwise be buried. The array controllers facilitate quick pattern changes, enabling operators to null out interference or peak weak signals from distant stations, effectively extending the reach of their receive capabilities by improving the signal-to-noise ratio.

DK8KW laboratory tests to get some indication about the ability to communicate with signals below noise level using Slow-CW.

"Instruments & Systems for Weather & Water Monitoring; weather stations, wind alarms, sensors for wind speed, wind direction, precipitation, temperature, relative humidity, barometric pressure, solar radiation, evaporation, rain & snow gauges, lightning detection."

Sense The Right Way To Go With The HANDI-Finder

Friis-It NF is the first iPhone OS based application that allows you to calculate noise figure, system sensitivity, and cascaded gain for an RF Receiver system

The Superantennas MP-1 portable HF antenna is analyzed for its design and field performance, particularly its high-Q loading coil and 3/8-inch mounting. The review details the antenna's construction, including an 8-inch vertical section, a large-diameter loading coil tuned by a sleeve, and a 4-foot whip that disassembles into six rods for transport. Initial testing with the supplied 10-foot ribbon cable "ground plane" yielded poor SWR and RF hot conditions, indicating an inadequate ground system. Further experimentation with longer radials and resonant counterpoises for each band improved matching and eliminated RF hot issues, but introduced significant operational complexity. The author notes the difficulty in optimizing both counterpoise length and coil setting without an antenna analyzer, and the sensitivity of the MP-1 to counterpoise deployment. The review also discusses the recommendation to tune for maximum received signals rather than minimum SWR, often necessitating an external ATU due to the antenna's typical low impedance. The **MP-1**'s critical dependence on resonant counterpoises for effective operation, especially when elevated, is highlighted as a major drawback for portable use. The author ultimately sold the antenna, concluding that despite its sound technical design, its fussy nature and the need for extensive counterpoise management or an ATU detract from its portability and convenience compared to simpler, less expensive dipole solutions. The **Superantennas MP-1** is deemed a flawed portable antenna, requiring considerable effort to achieve its claimed performance.

AO-51 Operating guidelines and introduction

By Floyd Sense K8AC

The MC3423 can protect sensitive circuity from power supply transients or regulator failure when used with an external "Crowbar" SCR.

Dealer of digital and analog panel meters Products include portable test equipment, oscilloscopes, recorders and temperature sensing equipment

Makers of QRP HF General Coverage Transceivers you can build. The Home of BITX transceivers, uBITX General Coverage Receiver-Transmitter. A general coverage, 10 watts HF SSB/CW transceiver kit with features you NEED for operating ease, convenience and versatility. It works from 3 MHz to 30 MHz, with up to 10 watts on SSB and CW, with a very sensitive receiver.

SWR and Transmitters Friends or Foes!, making sense of it!