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HotPaw MorseDecoder, an iOS application, provides real-time translation of Morse Code audio signals into plain text, leveraging the device's microphone or headset input. It incorporates a DSP narrow-band audio filter, adjustable from 300 to 2400 Hz, to mitigate background noise and QRM, enhancing signal clarity for decoding. The application offers both an automatic decoding mode and manual controls for fine-tuning parameters such as audio filter frequency, WPM dot/dash speed, noise threshold, and Farnsworth timing. The WPM detection automatically adapts from 8 to 40 WPM, with a QRQ High Speed mode extending this range to 30-80 WPM for faster code. A built-in spectrogram aids in identifying the precise audio frequency of the CW tones. User feedback indicates effective performance with various transceivers like the Yaesu FT-857 and Icom IC-R8600, particularly when manual settings are optimized. The app's ability to visually tune stations within the passband and decode speeds beyond an operator's manual capability has proven beneficial during contests and general QRP operation.

This PDF document, authored by KT4QW in October 2004, details the construction and modeling of a dual-band, horizontally polarized hanging rectangular loop antenna for **10 and 17 meters**. The design, adapted from *The ARRL Handbook*, utilizes _NEC4WIN95_ software for scaling and optimization, targeting a 50 ohm feedpoint impedance. The resource includes a bill of materials, step-by-step construction instructions, and a discussion of the antenna's radiation characteristics. It presents NEC-generated elevation and azimuth patterns, comparing the loop's performance to a half-wave horizontal dipole at the same height and frequency. The 17-meter element is centered at 18.140 MHz for low SWR across the phone band, while the 10-meter element is centered at 28.500 MHz. Construction involves 14-gauge stranded copper wire and Schedule 40 PVC spreaders, with the total wire length calculated by the formula: Length in feet = 1005/MHz. The feedpoint impedance can be adjusted by modifying the rectangular aspect ratio. The document specifies hoisting the antenna to at least a half-wave above ground for testing. It notes that a balun was tested and found to have no measurable effect on SWR or radiation characteristics. A 2-meter scale model is presented to illustrate the physical design, and a "rotator" string is incorporated for directional adjustment up to 90 degrees.

The Buddipole website showcases a range of portable amateur radio antenna systems, including the **Buddipole**, Mini-Buddipole, Buddistick PRO, and BuddiHEX, designed for rapid deployment and multi-band operation from 40 meters to 2 meters. Each product page details specifications, operational modes (dipole or vertical), and compatible accessories like tripods, masts, and baluns. The site also features portable DC power management systems such as the PowerMini 2 and PowerPlus, which include integrated battery chargers and solar controllers, catering to off-grid or field day setups. Instructional videos demonstrate antenna assembly, tuning, and deployment techniques for various configurations, including the VersaTee vertical and Mini-Buddipole. Customer testimonials and DXpedition highlights, such as operations from Montserrat (VP2M) and Dominica (J38), provide real-world examples of the equipment's performance in challenging environments. The company, established in 2001, emphasizes modularity, versatility, and efficiency in its product line, all manufactured in the USA. Shipping information, a 30-day return policy with no restocking fee, and contact details for their Heber City, Utah facility are clearly presented. The site serves as a direct sales portal, offering a comprehensive catalog of antennas, power solutions, and components for portable amateur radio enthusiasts.

The document details the optimization and construction of the _Maria Maluca_ antenna, a compact 6-band (20m-6m) directional beam. It presents a comparative analysis of shortwave antenna principles, highlighting the efficiency gains achieved by using an open feeder line and tuner as a resonant unit, contrasting this with the losses associated with traps or capacitive loads in multiband antennas. The resource specifically revisits an older South American 2-element design for 10, 15, and 20 meters, applying modern NEC-based software to develop a six-band version. Performance data is meticulously tabulated, showing impedance, free space gain, gain at 12m height, elevation angle, and front-to-back (F/B) ratio for each band from 20m through 6m. For instance, on 15m, the antenna achieves 5.1 dBd free space gain and 13.72 dB F/B ratio. The construction section provides practical guidance on element assembly using aluminum pipes and hose clamps, detailing the use of a heavy-duty glass fiber reinforced polyamide rod for electrical separation and bending strength. It also specifies the use of 450-ohm _Wireman_ line CQ 552 for the transmission line. The document includes diagrams for rod fixing, an air-wound balun, and a vertical elevation diagram for the 15m band, illustrating its DX qualification. It also discusses the antenna's suitability for portable and expedition operations, noting its compact transport dimensions (max 1.50m length, 12 lb weight) and quick assembly time (under 15 minutes). The author, Dipl.Ing. Helmut Oeller, DC6NY, is identified as a source for material kits.

The G5RV antenna, a popular multi-band wire antenna, typically employs a center-fed design with a specific length of 300-ohm or 450-ohm open-wire line acting as an impedance transformer, feeding a coaxial cable run to the shack. Its overall length for 80-10 meters is approximately 102 feet (31 meters) for the flat-top section, with a 34-foot (10.36 meter) matching section. The original design by Louis Varney, G5RV, aimed for efficient operation on 14 MHz (20 meters) as a 3-half-wave antenna, with the matching section providing a good match to 50-ohm coax on that band. While the G5RV offers multi-band capability, its performance varies across bands, often requiring an antenna tuner for optimal SWR on bands other than 20 meters. The matching section's length is critical for its impedance transformation properties, influencing the feedpoint impedance presented to the coaxial cable. Variations like the G5RV Junior and ZS6BKW utilize different flat-top and matching section lengths to optimize performance for specific band sets or to achieve a lower SWR without a tuner on certain bands, demonstrating the adaptability of the basic G5RV concept.

DL2HRF shortened dipole antenna for 80 meters band

A simple drawing of a shortened antenna for 40 meters by using a PVC tube

The Charles Gizmotchy high performance horizontal and vertical beam antennas. Two, Six, Ten and eleven meters antennas

How to homebrew an hex beam antenna for 20 17 15 12 10 meters band by VA7ST

VE7CA experiments on 160 meters band antennas, looking for better performances on reception.

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.

This resource details the computer-optimized design of the _ZS6BKW_ multiband dipole, an evolution of the classic _G5RV_ antenna. It begins by referencing the original 1958 RSGB Bulletin article by Louis Varney G5RV, explaining the operational principles of the G5RV's flat-top and open-wire feedline on 20m and 40m, noting its impedance transformation characteristics for valve amplifiers of that era. The article then transitions to the rationale for optimizing the design for contemporary solid-state transceivers requiring a 50 Ohm match. The core of the project involves using computer modeling to determine optimal lengths for the flat-top and matching section, aiming for a VSWR of less than 2:1 on multiple HF bands. It discusses the process of calculating feedpoint impedance based on antenna length and frequency, referencing professional literature from Professor R.W.P. King at Harvard University. The analysis also considers the characteristic impedance (Z(O)) of the open-wire line, identifying a broad peak of adequate values between 275 and 400 Ohms. Specific design parameters for the improved ZS6BKW are presented, including a shorter flat-top and a longer matching section compared to the original G5RV, with a velocity factor of 0.85 for the 300 Ohm tape. The article confirms acceptable matches on 7, 14, 18, 24, and 28 MHz bands when erected horizontally at 13m, and also discusses performance in an inverted-V configuration, noting frequency shifts. The author, Brian Austin ZS6BKW, emphasizes the antenna's suitability for modern 50 Ohm coaxial cable without a balun.

Thermocouple ammeters are very rare these days, but the job they were perfect for - measuring antenna currents - is still a modern requirement especially in respect to groundplane currents. By David A. Reid PA3HBB G0BZF

A vertical half-moxon for the 7 Mhz by F6IRF

Presents a comprehensive guide for constructing a broadband Hex Beam antenna, a popular directional array for HF operation. This design offers a compact footprint and excellent gain characteristics, making it suitable for limited space installations while providing significant performance advantages over omnidirectional antennas. The resource details the specific dimensions for a five-band Hex Beam covering 20, 17, 15, 12, 10, and 6 meters, emphasizing the critical element spacing and wire lengths required for proper resonance and pattern. It outlines the construction of the center post, spreaders, and wire elements, along with the feed point assembly, ensuring proper impedance matching. The project aims for a forward gain of approximately **5.5 dBi** on most bands, with a front-to-back ratio often exceeding _20 dB_. Building this antenna requires careful measurement and assembly, but the resulting performance provides a substantial upgrade for DXing and contesting.

Illustrates the specific wiring and configuration steps required to interface an SGC-230 Smartuner with an Icom IC-706 HF/VHF/UHF transceiver. The document details the necessary connections for power, control, and RF signal paths between the two devices, ensuring proper impedance matching and automatic antenna tuning functionality. It specifies the pin assignments for the IC-706's ACC socket and the SGC-230's control port, crucial for successful integration. Outlines the operational considerations for the combined system, including initial setup procedures and potential troubleshooting tips for common connectivity issues. The resource presents a clear, diagrammatic representation of the interconnections, which aids in visual comprehension of the required cable fabrication or modification. Covers the specific settings within the IC-706 menu that need adjustment to enable external tuner control, such as the 'TUNER' function and other relevant parameters. This ensures the transceiver correctly communicates with the SGC-230 for efficient antenna tuning across various amateur bands.

This is a popular antenna design as the performance is very good across the HF bands and requires little or no tuning. It is a dipole fed off center with a 4:1 current balun at the offset feedpoint. The antenna shown covers 80, 40, 20 and 10 meters with 15 meters and WARC bands

The ZS6BKW wire antenna, a variant of the G5RV, utilizes a specific 13m (42.6 ft) length of 450-ohm window line as its matching section, feeding a 28.5m (93.5 ft) flat-top element. This design aims for lower SWR on 40m, 20m, 17m, 12m, and 10m compared to a standard G5RV, often achieving SWR values below 1.5:1 on these bands without an antenna tuner. The feedpoint impedance transformation provided by the window line allows for direct connection to 50-ohm coax on multiple bands. F4FHH's experience involved constructing the ZS6BKW and evaluating its performance against an _OCF dipole_ (Off-Center Fed) on various HF frequencies. The article includes observations on SWR readings and operational effectiveness, highlighting the ZS6BKW's suitability for multi-band operation. The antenna's overall length, including the flat-top and window line, is approximately **41.5 meters** (136 feet), making it a significant wire antenna for fixed station use. Comparative analysis with the OCF dipole provided practical insights into the ZS6BKW's advantages and limitations, particularly concerning bandwidth and tuner requirements.

VQLog 3.1 - 782 is a shareware logbook program designed for Windows operating systems (95, 98, NT, 2000, ME, XP, Vista, 7, 10, or later), supporting resolutions of 800x600 or higher. It can also operate on macOS and Linux via virtualization software like Virtual PC for MAC, Oracle VirtualBox, or VMware. The software facilitates QSO access by date, callsign, prefix, square, DXCC, and other parameters, offering robust import capabilities for ADIF, Cabrillo, and ASCII files from various contest and logbook programs. Key features include comprehensive award tracking for DXCC, WAZ, WAC, WPX, WAS, IOTA, TPEA, DIE, VUCC, 100EACW, and up to 30 user-defined awards. It generates customizable summaries and graphical statistics for QSO activity, DX contests, Most Wanted Squares (MWS), propagation openings, and prefixes. VQLog supports DX-Spot reception and processing from DX-Cluster and PSK-Reporter with programmable warnings, integrates with callbook services like QRZ.COM and Buckmaster's CD, and offers online lookup. Electronic QSL and log upload support extends to LoTW, eQSL.cc, Clublog, and DXMAPS, with real-time updates for online logs. The program provides extended QSO information for VHF-DXers, including separate TX/RX frequencies, start/end times, propagation modes, and specific entry fields for MS, EME, and Tropo. CAT support for rig control and interfaces with ARSWIN and PstRotator for azimuth/elevation control are also included.

Operating a ZS6BKW antenna often involves understanding its lineage from the _G5RV_ design, with specific modifications by ZS6BKW to optimize performance on several bands. Through computational analysis and field measurements, the antenna's dimensions were refined to allow operation on 10, 12, 17, 20, and 40 meters without an antenna tuner. For 80, 30, and 15 meters, a tuner is necessary, though efficiency on 30 and 15 meters is noted as not particularly high. The physical configuration consists of two 13.755-meter radiating elements fed by a 12.20-meter section of 450-ohm ladder line. Tuning the antenna on the 20-meter band is critical, and any deviation in the ladder line's characteristic impedance necessitates recalculating the element lengths. The design is also referenced in the 12th edition of _Rothammel's Antennenbuch_, page 219. Proper common mode current suppression is crucial at the transition from ladder line to coaxial cable. This can be achieved with a common mode choke, such as several turns of coax wound into a coil or over a ferrite toroid like an Amidon T130. While a 1:1 balun is an option, it may introduce issues.

40 meter vertical antenna construction, a shortened easy-to-build vertical, with no-radials, made from surplus military camouflage poles

A copper pipe Hentenna for 144 MHz. The Hentenna, a compact, high-gain loop antenna developed in Japan in the 1970s, offers approximately 5.1 dBd gain, comparable to a three-element Yagi. Adapted for 2 meters, it is crafted from copper pipe for simplicity, affordability, and broadband performance. Requiring no feed-point tuning, its construction involves soldering standard copper fittings. Installation demands non-conductive materials to minimize signal disruption. Versatile for vertical or horizontal polarization, it is ideal for FM, repeater, SSB, or CW applications. This design emphasizes practicality and performance for amateur radio enthusiasts

Power supplies, electrical testers, battery analyzers, cable tester, rf generators, spectrum analyzers, Digital/Analog Oscilloscopes, Multimeters , attenuators, frequency counter

Demonstrates the design and construction of a 9-element Yagi antenna for the **70 cm band** (432 MHz), based on the DK7ZB concept. The resource details EZNEC+ calculations for a single antenna, providing gain, sidelobe suppression, and front-to-back ratio figures. It also presents a comprehensive analysis of stacking two such antennas, including optimal stacking distance (1000 mm) and the resulting performance enhancements for the stacked array, such as an increased gain of 17.03 dBi. The article includes detailed drawings, wire file dimensions in millimeters, and azimuth/elevation plots for both single and stacked configurations. Practical construction steps are documented with original photographs, illustrating element mounting, the **28 Ohm matching system** using two quarter-wave 75 Ohm transmission lines, and the critical N-connector wiring. It also covers the iterative process of fine-tuning the driven element length to achieve a return loss of 20 dB, validating the EZNEC+ simulation results with actual measurements.

One specific challenge in the KazShack, operating Single Operator Two Radios (SO2R), involved sharing a K9AY receive antenna between two transceivers without direct RF connection or manual feedline swapping. The solution, detailed in this project, adapts the **W3LPL RX bandpass filter** design to split 160m and 80m signals, feeding them to separate radio inputs while maintaining isolation. This approach also addresses the issue of strong broadcast band interference from a nearby 50KW WPTF transmitter on 680kc. The construction utilizes T-50-3 toroids and NP0 ceramic capacitors, built in a "dead bug" style on copper clad board. Each band's filter coils are identical and resonated to the desired frequency using an MFJ-259 antenna analyzer. A single DPDT relay, controlled by a remote toggle switch mounted on an aluminum panel, facilitates quick band switching between radios, simplifying low-band operations. While some signal loss is noted, the expected lower noise levels from the receive antenna are anticipated to compensate, potentially reducing the need for constant volume adjustments during toggling between transmit and receive antennas.

Presents the design and performance of a 4-element wire Yagi antenna for the 40-meter band, building upon VE3VN's earlier 3-element switchable wire Yagi. The resource details the antenna's evolution, highlighting the transition from a 3-element to a 4-element configuration and the resulting improvements in gain and front-to-back ratio. It provides specific insights into the antenna's construction and expected operational characteristics. VE3VN shares insights from field results, noting the antenna's performance on 40 meters. The discussion includes the antenna's pattern and matching characteristics, crucial for any DXer or contester looking to optimize their signal on this popular HF band. The author's experience with the previous 3-element design informs the enhancements made to this 4-element iteration. The article includes a visual representation of the antenna's current view, offering a practical perspective on its physical layout. It serves as a valuable reference for hams considering a directional wire antenna for 7 MHz operations, demonstrating a practical approach to achieving enhanced directivity and gain.

The ZS6BKW antenna, a popular multiband wire antenna, offers improved band matching compared to the traditional G5RV. This construction guide details the process, beginning with specific dimensions: 13.11 meters (43 feet) for the 450-ohm ladder line and initial dipole arm lengths of approximately 14.8 meters each. It emphasizes the critical role of an _antenna analyzer_ for accurate tuning, particularly for determining the velocity factor of the ladder line and achieving a 1:1 impedance match. The article outlines the materials required, including a 1:1 current balun, 450-ohm window line, wire for the dipole arms, and a 50-ohm non-inductive resistor for testing. It provides a step-by-step procedure for cutting the ladder line to its electrical half-wavelength, explaining how to calculate the velocity factor using measured and free-space frequencies. For instance, a measured 50-ohm impedance at 12.54 MHz with a calculated free-space half-wavelength frequency of 11.44 MHz yields a velocity factor of 0.91. Final adjustments involve hoisting the antenna to its operational height and fine-tuning the dipole arm lengths to achieve optimal SWR, specifically targeting 14.200 MHz. The _ZS6BKW_ design is noted for its performance on 80m, 40m, 20m, 10m, and 6m, though it is not optimized for 15m operation. The author, _VK4MDX_, shares practical tips for durable construction using stainless steel wire and cable clamps.

This resource, "Transistor Audio Preamplifier Circuits," offers comprehensive design guidelines for constructing **bipolar transistor** audio preamplifiers. It delves into critical aspects such as quiescent current setting, voltage gain calculation, and the impact of various component choices on circuit performance. The content provides several _schematic diagrams_ illustrating different preamplifier configurations, including single-stage common emitter and two-stage designs, alongside explanations of their operational characteristics and practical implementation considerations. The analysis extends to frequency response, noise performance, and distortion, providing insights into optimizing these parameters for specific audio applications. The resource presents calculated gain figures for various stages, demonstrating how to achieve desired amplification levels. It also discusses the importance of proper power supply decoupling and input/output impedance matching, crucial for integrating these preamplifiers into larger audio systems or ham radio transceivers. The practical application of these designs is evident in their suitability for microphone preamplifiers or general-purpose audio amplification.

The Vee Beam antenna project presents a versatile solution for hams, enabling operation across all eight High Frequency bands (80m to 10m) with significant gain on 20m to 10m. This easy-to-construct antenna utilizes two long wires at an angle, enhancing directional performance and minimizing ground losses. With a low visual profile, it is discreet and effective for various applications. The design allows for optimal leg lengths and included angles, ensuring robust performance while maintaining simplicity in construction and operation. The V Beam antenna is an aerial that you can use on all eight High Frequency amateur bands (80, 40, 30, 20, 17, 15, 12 and 10m) with an antenna tuner, and which gives significant gain on the five bands from 20 to 10 meters band.

The document provides a detailed guide on modifying an inverted-L antenna to include the 160 meters band. This enhancement allows amateur radio operators to utilize the lower frequency effectively, which is crucial for long-distance communication, especially during the night. The inverted-L design is popular due to its compact size and ease of installation, making it suitable for various environments. By adding top band capabilities, operators can engage in DXing and contesting on 160m, expanding their operational range and opportunities. The guide includes practical tips and considerations for construction, ensuring that the antenna maintains its performance across the extended frequency range. It discusses the necessary adjustments and materials required for the modification, along with potential challenges and solutions. Whether you are a seasoned operator or a beginner, this project can enhance your station's capabilities, allowing for more versatile operations and improved signal quality on the 160m band.

A 500-watt mobile antenna project details the conversion of an old 10m hamstick into a highly efficient, multiband "bugstick" for HF operation. The core modification involves replacing the original coil with 25 turns of 6 turns-per-inch, 1.5-inch diameter coil stock, fabricated from #14 wire. This design, intended for a 3-magnet mount on a vehicle cab, achieves resonance on multiple bands by shorting out specific turns on the coil, similar to a **bugcatcher** antenna. Measurements taken with an MFJ-259 analyzer on a GMC pickup show 0 turns shorted for 20 meters (14.2 MHz), 10 turns for 17 meters, 16 turns for 15 meters, 19 turns for 12 meters, and 23 turns for 10 meters. The construction emphasizes using UV-resistant tie-wraps and #14 solid wire with crimp lugs for robust RF connections, bypassing the fiberglass rod for current flow. A bonus section details a 40-meter version, utilizing 48 turns of 8 TPI, 2-inch diameter coil stock.

Over 1,000 stations in approximately 60 countries were worked using this modified twin-lead folded dipole, demonstrating its effectiveness with just 4 watts on 20 meters. This design, adapted from an ARRL Handbook concept, eliminates the shorting strap found in traditional folded dipoles, simplifying construction while maintaining performance. It utilizes readily available 300-ohm TV antenna feeder ribbon, making it a cost-effective solution for radio amateurs. The antenna's robust construction allows it to handle up to 100 watts without issues, even without a **balun**. The inclusion of a variable trimmer capacitor at the stub provides flexibility for tuning across different frequencies within a band, a practical feature for operators using transceivers like the Icom 735. Formulas are provided to calculate the precise dimensions for any desired operating frequency, enabling customization for various **HF bands**.

A simple RF power amplifier initially designed for 40 meter band can work on 10 15 20 40 80 meters

The two linear amplifiers are ment for use with QRP SSB/CW/FM/AM transmitters on the amateur bands 15 and 17 meters can be powered from a 12 volt DC supply by ON6MU

The circuit described below will substantially reduce or completely eliminate interference from almost any local source whilst leaving the wanted signal relatively unaffected, even though it may be on the same frequencey by TREVOR, G3ZYY

The Collins TRC-75 autotune linear amplifier, owned by JF2SVU, is presented with a focus on its internal modifications. This QRO amplifier utilizes three 4CX250 tubes in parallel for its final stage, delivering 1 KW output power. Notably, the amplifier achieves full power with only 100 mW of RF input, a characteristic often associated with Collins designs. The original 400 Hz power supply has been converted for easier shack integration, and the entire RF and power supply sections have been rehoused into a compact, clean enclosure. The control unit, positioned above the amplifier, features three meters for individual vacuum tube IP monitoring and a multi-meter on the right. A dedicated 7 MHz receiver, recently completed, is also part of this integrated system. The autotune functionality means the main amplifier unit only requires connections for power, control, and coaxial cables, simplifying its operation. Key components like the 4CX250 tubes and NF capacitors are visible, along with the gearing mechanism for the final tank circuit. A timer and relay system manages high-voltage delay and cooling fan off-delay, although the cooling fan's airflow is noted as somewhat insufficient. A central volume control, which experienced a contact issue, is also highlighted.

The G5RV multiband HF antenna, designed by Louis Varney (G5RV) in 1946, is a popular compromise antenna offering good overall performance on most HF bands when paired with an external antenna tuner. The basic full-size G5RV measures 102 feet across the top for 80 through 10 meter operation and is fed at the center via a 34-foot low-loss feed-stub. This interaction between the radiating section and the feed-stub facilitates matching across 80-10 meters with a standard tuner, often eliminating the need for ladder line directly to the shack. The antenna's design center frequency is 14.150 MHz, configured as a 3/2-wave dipole on 20 meters, with its 102-foot length derived from long-wire antenna formulas. Construction details emphasize the matching section, which can be open wire, ladder line (window-type), or TV twin lead. Each type has a specific velocity factor (VF) affecting its physical length for an electrical half-wave on 14 MHz; for instance, open wire requires 33.7 feet (VF 0.97), ladder line 31.3 feet (VF 0.90), and TV twin lead 28.5 feet (VF 0.82). The article provides formulas for calculating these lengths and discusses the antenna's behavior on individual bands, from 3.5 MHz where it acts as a shortened dipole, to 28 MHz where it functions as two three-half-wave long-wire antennas fed in-phase. Practical construction notes include recommendations for vertical descent of the matching section, sealing the coax junction, providing strain relief, and winding a coaxial choke coil to mitigate common mode current. The resource also presents dimensions for double-size (204 ft) and half-size (51 ft) G5RV versions, along with their corresponding matching section lengths for various line types, making it a versatile reference for hams considering this classic wire antenna.

Accurately determining an antenna's feedpoint impedance is crucial for optimal performance, especially when experimenting with new designs or making adjustments. While SWR meters provide basic information, a full complex impedance measurement reveals the resistive and reactive components, which are essential for proper matching. Modern antenna analyzers, like the _Palstar ZM30_ or MFJ259B, simplify this task, but measurements taken through a transmission line require careful interpretation due to impedance transformation. This resource details a calibration method to precisely account for the effects of the feedline. It explains how a transmission line can significantly alter the measured impedance, illustrating this phenomenon with a Smith Chart example where an 80m antenna's [22 + j6] Ohms feedpoint impedance transforms to [82 + j45] Ohms after a 10m line. The guide demonstrates using a transmission line calculator applet, such as the one by W9CF, to reverse this transformation. It outlines the process of calibrating a specific length of RG174 coax, showing how an initial 26ft estimate was refined to **25.85ft** to accurately predict a known 22 Ohm load, significantly improving accuracy over uncalibrated results.

Bird Technologies supplier of RF products, like RF Meters, Bird 43, VNA, Spectrum analyzers, attenuators, transmitters combiners, dummyloads, terminators and replacement parts

Controlling amateur radio transceivers remotely often requires dedicated software to interface with the radio's CAT (Computer Aided Transceiver) system. CATSPAW is a software utility specifically developed by N2OHZ for the Yaesu FT-100, facilitating computer-based control over various radio functions. The software provides an interface for adjusting parameters such as frequency, mode, and other operational settings, which can be particularly useful for remote station operation or automated tasks. While the specific features and user interface details are not extensively documented on the download page, the primary function centers on providing a digital control layer for the _FT-100_. This allows operators to integrate the transceiver into a larger station setup that might include logging programs or digital mode applications, enhancing the overall operational flexibility. The utility's design focuses on direct control, leveraging the radio's internal command set. As a downloadable executable, _CATSPAW_ represents a common approach to radio control software from its era, offering a direct link between a personal computer and a specific transceiver model.

Lage collection of 6 Meters and 2 meters QSOs, recorded in real audio format by OE3MWS

Optimizing a G5RV or ZS6BKW multiband wire antenna for HF operation often involves addressing common SWR issues and understanding feedline characteristics. This resource chronicles the construction and performance evaluation of a G5RV, initially built for 80m, 40m, 15m, and 10m bands, by a newly licensed Foundation operator. The author details the selection of materials, including 3.5 mm stainless steel wire for the doublet arms and enameled copper wire for the open-wire feeder, and the initial decision to omit a balun based on common online information. The narrative highlights the initial disappointing performance, characterized by high receive noise and poor signal reports on 80 meters, despite the transceiver's internal ATU achieving a 1:1 match. This led to experimentation with a coax current balun and further research into G5RV myths, such as SWR claims and the necessity of a balun. The author then describes modifying the antenna to the ZS6BKW configuration, which involves specific changes to the doublet and feedline lengths, and integrating a 1:1 current balun wound on a ferrite toroid. The modifications resulted in improved reception and transmit performance across the bands.

Homebrewed handheld RF powermeters for various sensors by DL5NEG

Information on equipment manufactured by the Bird Electronic Corporation, wattmeters, RF loads, switches by I0JX

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.

This project details the construction of a **full-sized 40-meter vertical antenna**, born from a renewed interest in 7 MHz operation and a desire for improved effectiveness over simple dipoles. The author, K5DKZ, initially focused on VHF experimentation, which provided an inventory of aluminum tubing and fiberglass spreaders for this endeavor. Before this vertical, K5DKZ utilized an 80/40 meter inverted-vee trap dipole and a 40-meter broadband dipole, but now primarily uses a pair of full-sized, phased, quarter-wave verticals spaced 35 feet apart for serious 40-meter work. The construction involves a base-heavy design for stability, using a 44.5-inch section of 1-1/4 inch steel TV mast driven into 1-3/8 inch aluminum tubing, insulated by a 105-inch section of Schedule 40 PVC pipe. The assembly reaches 31 feet, close to the 32 feet required for a quarter-wavelength on 40 meters, with fine-tuning achieved by winding wire onto a fiberglass spreader. The design is explicitly presented as a foundation for a two-element 40-meter Yagi beam, outlining modifications like substituting aluminum for steel in the base and using an inductive hairpin match for the driven element. The article also discusses tuning considerations for a large 40-meter beam, noting the 100 to 200 kHz upward frequency shift when raised, and suggesting methods for installation on a tower. The author emphasizes the cost-effectiveness and good performance of the monopole approach, especially when multiple verticals are needed.

The grounded half loop describe in this article is basically a half wave length wire on 80 Meters. The 80M grounded half loop antenna, inspired by a 1984 QST article by SM0AQW, is a compact solution for limited spaces. Comprising a 127-foot wire fed against ground and supported by radials, it balances performance and practicality. Despite compromises in length and proximity to structures, the antenna delivers strong signal reports and effective multi-band tuning using an SGC 237 antenna coupler. Ideal for CW operation, it offers low SWR on 80-10M, though noise levels and safety considerations warrant attention. This versatile design excels in constrained environments.

The Yaesu VX-5R, manufactured between 199x and 200x, offers a transmit frequency range covering 50-52 MHz, 144-146 MHz, and 430-440 MHz for European models, with US versions extending to 50-54 MHz, 144-148 MHz, and 430-450 MHz. Its receiver boasts an impressive wideband capability from 0.5 MHz to 999 MHz, with cellular frequencies blocked in some regions. The unit provides up to 5 watts RF output on 6 meters and 2 meters, and 4.5 watts on 70 centimeters, with selectable lower power settings down to 300 mW. This handheld transceiver utilizes a double conversion superheterodyne receiver system, featuring a 47.25 MHz first IF for FM and 45.8 MHz for WFM. Key specifications include a frequency stability of ±5 ppm across a wide temperature range and a current drain of 25-150 mA on receive. The VX-5R supports 220 regular memory channels with alpha tags, 3 home channels, and 10 NOAA weather channels, all stored in non-volatile EEPROM. Additional features include CTCSS/PL and DCS with tone search, ARS, ARTS, an internal voltmeter, and a Spectra-Scope. The device operates on a 7.2 VDC battery pack or 10-16 VDC external power, weighing 255 grams with dimensions of 58x88x27 mm. The VX-5R was also available as the metallic silver VX-5RS.

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.