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HamCalc is a free collection of calculators for radio amateurs include Antenna ERP calculations, Attenuators, Audio Filter design, Coil Winding, Decibels, Great Circles map and calculator, HF Filters, HF Traps, Metric conversions OP Amps QRA Locator to Latitude/Longitude, Radio Horizon calculator, Resonance Satellite orbit calculator Timer calculations (555 timer)Zener Diode calculations Download zip By G4VWL

HF and VHF amplifiers homebrewed by GM3WOJ

BIRD RF power measuring, new and used, HENRY RF power amplifiers (used HF amps), TOHTSU coaxial relays, SAMLEX power supplies, RFI chokes reduce interference, Parts parts, tubes, Used amplifiers, radios, antennas and accessories, Los Angeles, CA.

Design guidelines for Op Amp audio preamplifier circuits by Mike Martell N1HFX

Amplifier repair and conversion, specialize in converting HF amplifiers to operate as monoband amps on 50 MHz

Technical specifications and details of the Yaesu FL-2100B HF Power Amplifier

The Kenwood TS-870S HF transceiver features two state-of-the-art 24-bit 20 MIPS DSP chips, providing over 100dB out-of-passband attenuation and CW bandwidth adjustable to 50 Hz. It operates across 160-10 meters with 100 watts output, incorporating digital filtering, a beat canceller, and 100 memory channels. The radio also includes a transmit equalizer, RX antenna input, and a K1 Logic Keyer, enhancing signal processing and operational flexibility for amateur radio operators. Advanced capabilities include IF stage DSP, dual noise reduction, and an auto notch filter, all contributing to superior signal reception and clarity. The TS-870S offers a variable AGC, voice equalizer, and an RS-232C port for computer control, with Windows™ software supplied. Its built-in automatic antenna tuner functions on all bands for both transmit and receive modes, streamlining station setup and operation. Available accessories such as the DRU-3A digital recording unit, SO-2 high stability crystal oscillator, and VS-2 voice synthesizer option further extend the transceiver's utility. The unit requires 13.8 VDC at 20.5 Amps and is supplied with an MC-43S hand microphone, making it a comprehensive station component.

The IZ3MEZ Web DX Cluster presents real-time amateur radio DX spots across 20 distinct frequency bands, spanning from **LF (2190m)** at 135.7 kHz up to **SHF (QO-100)** at 10499 MHz. It displays the DX callsign, frequency, DXCC entity, spotter callsign, and spotter DXCC entity, along with any accompanying comments. The cluster also lists various operating modes such as CW, RTTY, FT8, FT4, FT2, PSK, and SSTV, and supports special operating activities like QRP/P and specific award programs including IOTA, POTA, SOTA, WCA, and JOTA. The cluster's interface provides a dynamic feed of the latest 50 spots, continuously updated with precise timestamps. It offers direct **Telnet protocol** access for users preferring a command-line interface, with configuration instructions provided. The resource also integrates with other spotting networks like RBN and PSK Reporter, enhancing its utility for DXers and contesters seeking propagation information and activity monitoring across a broad spectrum of amateur radio frequencies.

This resource documents numerous QRP (low power) portable amateur radio operations conducted by W1PID, Jim Cluett, primarily from various outdoor locations in New Hampshire. The content includes detailed accounts, photographs, and operational specifics for over 350 individual "QRP Adventures," often involving hiking, biking, or kayaking to remote sites. Each entry typically highlights the location, date, bands and modes used (frequently CW on HF), and notable DX contacts made with minimal power, sometimes as low as 200mW WSPR. The site serves as a chronicle of practical QRP field operation, demonstrating successful DXing and contesting from challenging environments. It showcases diverse operating scenarios, from mountaintops like Cannon Mountain and Knox Mountain to lakeshores, riverbanks, and even marine mobile operations. The documented contacts span numerous DXCC entities across Europe, Asia, and the Americas, providing empirical evidence of QRP's efficacy in varied propagation conditions and terrains. Specific events like the Worked All Germany contest, 13 Colonies Event, and CWT sprints are also featured.

The N1HFX thermal cooling fan controller project details a practical circuit designed to manage cooling fan operation based on temperature, a common requirement for high-power amateur radio equipment. This build utilizes a **LM34** temperature sensor, providing a linear voltage output directly proportional to Fahrenheit degrees, simplifying the control logic. The circuit's core functionality involves a comparator that activates the fan when a preset temperature threshold is exceeded, ensuring efficient cooling and reducing unnecessary fan noise. This controller is particularly useful for amplifiers, power supplies, or transceivers that generate significant heat during operation. The design incorporates a _TIP120 Darlington transistor_ to drive the fan, capable of handling up to 5 amps, making it suitable for a range of fan sizes and current requirements. Field results indicate stable temperature regulation, preventing thermal runaway in enclosed environments. Construction involves readily available components, making it an accessible project for hams looking to optimize their station's thermal management.

Circuit designs for IC audio amplifiers by N1HFX

Thoughts build a solid state legal-limit amplifier for amateur radio use.

Over 100 currently valid callsigns for the Bailiwick of Guernsey are listed, encompassing full, intermediate, and foundation licenses, alongside special event and club station calls. The resource clarifies various callsign types, such as 2U0*** for intermediate licensees with a 50-watt limit and GU0*** for full licensees operating up to **400 watts**. This detailed compilation also includes specific QSL routing instructions for visiting operators and past residents, often referencing their home callsigns like _G4DIY_ or _DJ8NK_. The callbook further acknowledges "silent keys," providing a respectful record of former Guernsey amateurs, complete with their callsigns and dates of passing where available. It also lists local repeaters and provides important QSL bureau information, noting that only US dollar bills are accepted for direct QSLs, not English stamps or Euros. For full addresses, the resource directs users to _QRZ.com_, emphasizing that the provided information is offered in good faith.

King Conversions has extensive experience in amplifier repair and conversion King Conversions specialize in converting HF amplifiers to operate as monoband amps on 50 MHz

One of the featured products, the V350 CAMP, is a multiband vertical antenna covering 6 to 80 meters, priced at R$ 799,90, demonstrating the range of ready-to-use solutions available. The inventory includes various antenna types such as **HF**, **VHF**, and **UHF** designs, along with dual-band options like the J-Pole Dual V/UHF for R$ 235,00. For those building their own arrays, the store stocks essential components like element holders, clamps, junction boxes, and aluminum plates, alongside specialized items such as the KIT Isolador Central Dipolo - 01DX for R$ 99,90. The shop also provides a comprehensive selection of installation hardware, including diverse antenna mounts, PTT supports, and various coaxial cables like RG58 and RG213, with prices up to R$ 849,90 for RG213. Connectors such as UHF male PL259 and various adapters are readily available, ensuring compatibility for different setups. Additionally, specialized items like side handles for popular transceivers such as the FT857/891 and IC7300 are offered, catering to specific equipment needs. Beyond antennas, the store supplies practical accessories like transport bags, 12V power cables for transceivers, and even branded merchandise like the Antena Kit mug. Rodrigo Gonçalves, PP5BT, manages the operation from Blumenau, SC, Brazil, providing direct contact via WhatsApp at +55 47 9.9985.0155.

QSK 2500 enhances HF amplifiers by enabling full break-in (_QSK_) operation, allowing for seamless communication during CW transmissions. This device supports **all** HF transceivers that are QSK-compatible, ensuring versatility across various setups. The QSK 2500 facilitates quick switching between transmit and receive modes, which is crucial for effective DXing and contesting. With its straightforward installation, operators can achieve **improved** responsiveness in their communications without the need for extensive modifications to their existing amplifiers. This project is particularly beneficial for those engaged in high-speed CW operations, where timing is critical.

Not a project yet, but very theoretical thoughts about very practical amplifiers!

Showcasing German engineering, ANjo Antennen develops and manufactures a diverse portfolio of amateur radio and commercial antenna products. Their offerings span a wide frequency range from 1.8 MHz to 3000 MHz, emphasizing electrical and mechanical precision for longevity. The company actively participates in events like FUNK.TAG Kassel, providing opportunities for direct engagement and order pickup. ANjo's product line includes high-performance **Yagi antennas** optimized for Tropo and EME, along with multi-stacked Quad antennas designed for contest operations, featuring wide horizontal and narrow vertical beamwidths. They also produce circularly polarized satellite antennas, some with switchable LHCP/RHCP, leveraging their commercial satellite antenna expertise. Beyond amateur applications, ANjo provides flexible, custom antenna solutions for commercial sectors such as BOS, EMC measurements, and telemetry. Their commitment to quality is evident in the Premium-Line antennas, which utilize **1.4301 (V2A) stainless steel** for mast clamps and connectors, ensuring durability and corrosion resistance. They also offer end-fed HF multiband wire antennas, known for their compact footprint and discreet installation.