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A rebuild job on a Heathkit SB-200 amplifier by N4NAB

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.

Benefits in implementing a remote antenna switching system and a sample remote antenna switch project

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

This article loaded with nice pictures and schematics, describes a 160-10 meter linear amplifier that uses a pair of 3-500Z triode power tubes. It was designed and constructed by William Moneysmith, W4NFR. The amplifier features fast warm up and 1500-Watt RF output with 100-Watts of drive.

An example of how to control a Yaesu FT-817 with an Arduino to make a multi-band CW beacon.

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.

Review by Clive Davies, G4FV

Amateur Television products, online store for ATV transmitters receivers, LCD controllers, wireless cameras, video senders, accessories, power amplifiers based in UK

Negative feedback is often referred to as shunt feedback in conjunction with emitter degeneration.

Some sound samples of received signals mainly on VHF-band

The Yaesu FT-1000MP Mark-V, introduced at Dayton 2000 Hamvention, features a higher RF power of **200 W PEP** and a Class-A amplification SSB mode at 75 W. Key enhancements include an _Interlocked Digital/Analog Bandwidth Tracking system (IDBT)_, a Variable Front-End Filter (VRF) preselector, and improved ergonomics, notably a multi-function shuttle jog dial. This model, a successor to the 1996 FT-1000 and FT-1000MP, was designed to compete with high-end transceivers, despite its retail price of $4200 initially. The transceiver's physical dimensions are 406 x 135 x 348 mm (16 x 5.3 x 13.7 inches) with a weight of 14 kg (31 lbs), making it substantial. Its rear panel offers over 20 connections, including power, external DSP speaker, BAND DATA I/O, ALC, and multiple interface jacks for DVS-2, Packet, and RTTY. The unit also provides two keyer inputs, a DB9M serial interface for CAT, and two PL female antenna connectors, plus additional receive antenna jacks. Despite its advanced internal architecture, including two independent receivers with their own IF filters and AGC loops, the display technology, utilizing fluorescent discharge rather than LCD, contributes to an older aesthetic. The control panel is extensive, featuring 92 knobs and buttons, alongside numerous LED indicators for various modes and functions.

A method of installing a PL259 coax connector, a complete tutorial on how to solder Amphenol 83-1SP connectors

Using patch antenna for amateur radio reception of the 13cm band with a sample 2.4 GHz LHCP patch antenna by K3TZ

STAMPFL Morse key, founded by Heinz Stampfl HB9KOC in Switzerland. Stampfl manufactures Morse Key in small batches and in the usual Swiss Quality.

The RoadTrek design presents some unique challenges to us hams. Here an example of a VHF and HF antenna installation on a VAN

A cooperative venture between MSUARC and Calloway County Fire and Rescue

What become our QSL once sent ? QSL routes, IRC and green stamps, the best and worst practices.

Extremely reliable FET preamplifier can handle several watts directly into either the input or the output without failure

Ham radio site devoted to classic collectible amateur and military radios, featuring vintage ham radio color photos and commentary, free downloadable manuals and pamphlets and links for ham radio hobbyists.

1500 watts PEP output from a Kenwood TL-922 amplifier requires careful attention to parasitic suppression and component selection to ensure stability and longevity. This resource critically examines common modifications, often based on anecdotal evidence rather than sound engineering principles, that can degrade performance or introduce new issues. It highlights how replacing aged components often gets misattributed to the efficacy of unnecessary modifications, leading to widespread misinformation within the amateur radio community regarding amplifier stability. The article details specific, effective modifications for the TL-922, such as shortening anode-to-chassis and anode-to-grid paths to improve VHF stability and efficiency. It addresses issues like incorrect capacitor types in the tank circuit, inadequate grid grounding, and poor RF sheet metal design, providing practical solutions like adding direct ground connections for the plate tune variable capacitor. The author also discusses proper parasitic suppressor design, emphasizing the importance of lead length and component selection for optimal performance and harmonic suppression, contrasting these with less effective or detrimental 'magical suppression kits'.

80-meter peilontvanger / receiver includes printed circuit sample and list of components

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

Pre-inked - re-inkable stamps

Repairing and restoring a Yaesu FL-2100Z amplifier

High pass filter schematics for TVI and examples of finished filters

Low signal, noise-high AC gain preamplifier

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

The Yaesu FL2100Z is a HF linear amplifier rated for 1200W PEP input, and using two 572B triode tubes. This article explores the recommended operating conditions, and alternatives.

In this PDF article Zack Lau describe how to homebrew a four element yagi beam antenna for 50 MHz band, including how to build mounting blocks and tubing clamps to hold elements.

This is an internet resource for those interested in guitar amplifiers, vacuum tubes, and design tools such as SPICE modelling.

A K9AY loop antenna project done with Far Circuits pc boards for the antenna switch and bandpass filter and preamp by K7SFN

The California Polytechnic State University Amateur (Ham) Radio Club (CPARC) has a long tradition of communications service on campus and in the community of San Luis Obispo. The club was founded in 1947, making the Cal Poly Amateur Radio Club the second oldest club on campus

Repairt a Heathkit SB-220 Linear Amplifier with a bad Plate Voltage meter

Article on tubes and their usage in power amplifiers design. Explain failures of tube in RF power amplifiers, a common problem in the SB-220 SB-221, TL-922 and other amplifiers.

Tests on a preamplifier for 50 MHz installed right at the feedpoint of the antenna.

Includes W1BB Stew Perry letters, and a sample QSL cards of dated 1963

Kenwood Ibérica's online presence details their extensive product line, including the NEXEDGE NXDN and DMR digital radio systems, alongside traditional analog offerings. The site categorizes transceivers by mode, such as HF / Todo Modo (All Mode), and portable/mobile VHF/UHF units, catering to various amateur radio operating preferences. This includes specific accessories like batteries, chargers, microphones, and programming cables, essential for maintaining and customizing radio equipment. The Spanish portal also highlights Kenwood's broader electronics portfolio, extending beyond amateur radio. This encompasses car electronics, featuring navigation and multimedia systems, as well as marine receivers and speakers. The product range covers everything from CD and CD-less car receivers to power amplifiers and DashCam/RearCam solutions, demonstrating the brand's diverse market reach. Beyond communications gear, the site presents home audio systems, including all-in-one receivers and portable party speakers. This breadth of offerings underscores Kenwood's long-standing presence in both the consumer electronics and two-way radio sectors, providing a centralized resource for product information and support.

Heathkit SB-220 Amplifier modification by KE5YA

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 HotPaw Morse Code Decoder application for macOS processes audio input to transcribe Morse code characters into text. It presents both an audio spectrum graph and a tone amplitude graph, which aid in configuring a narrow band audio filter. Operators can set the audio filter for tone frequencies between 400 and 1600 Hz, optimizing reception for various CW signals. The software offers user-configurable settings, including WPM dot/dash speed detection, a noise threshold level, and the option to use Farnsworth timing for inter-character spacing. The Morse code WPM detection automatically adapts from approximately 8 to 40 WPM, with a lock feature for the estimated speed. A High Speed WPM Mode is available for code speeds ranging from 40 to 80 WPM, catering to faster CW operators. The application's decoding performance is influenced by signal level, signal-to-noise ratio, frequency and WPM stability, keying quality, and proper configuration, with an initial learning phase required for WPM estimation to stabilize. An external microphone or line-in may be necessary for optimal performance on some MacBook models to mitigate fan noise or room reverberations. Version 1.4.4, updated on November 11, 2021, includes compatibility improvements for newer macOS releases. The developer, Ronald Nicholson of HotPaw Productions, does not collect any user data from the application.

A home made VHF 2.5kw RF power amplifier made with a GS35B Triode and designed by Frank F1CXX built in 2003

Article about assembling of a Dick Smith Electronics (DSE) 100 Watt VHF Linear Amplifier kit.

A pdf file with drawings and instruction to properly assembly and solder most popular coax cable connectors

VHF RF power amplifiers manufacturerr

The TMB-1 is an RF amplifier unit / receiving accessory that can be used with a low-impedance broadband loop, a high-impedance terminated loop (such as a Pennant, Flag, or Kaz Delta), and whip (telescoping rod) antennas.

QST Article on what you should know about matching networks for class C RF power amplifiers

low-noise amplifier for HF reception, amplifies signals 80 to 100 times between 0.15 MHz and 30 MHz. It will let you hear more signals with your RTL-SDR plus Ham-It-Up setup

This program simplifies the design of the single-ended Class E amplifier. Operation is intuitive and encourages "tuning" and exploration.