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The project details modifications to an ARK-40 QRP CW transceiver kit, specifically replacing its original thumbwheel frequency selectors with a **BASIC STAMP BS-II microcontroller** and an optical shaft encoder. The redesigned control circuitry outputs a BCD code to the ARK-40's synthesizer, enabling more convenient knob-type tuning. This modification significantly alters the user interface, moving from discrete frequency selection to continuous tuning. Operating frequency is presented on an LCD readout, offering two distinct display modes: a "bandspread dial" mode that simulates an analog dial scrolling across the display in 1 kHz increments, and a conventional digital readout with 100 Hz resolution. Pushing the main tuning knob toggles between these modes, providing both rapid band traversal and fine-tuning capabilities. The software for the BASIC Stamp is written in P-Basic, addressing the challenge of accurate analog dial simulation. Physical modifications include fabricating a custom PC Board for the STAMP, mounting it with an L-bracket to the optical encoder, and creating a new front panel. The front-mounted speaker was relocated to accommodate the new tuning knob and display, transforming the **ARK-40 transceiver** into a more user-friendly rig with its built-in CW keyer and 5 watts of power.

Arrl document about invisible antennas and indoor systems. It is important to consider that few compromise antennas are capable of delivering the performance one can expect from the full-size variety. But the patient and skillful operator can often do as well as some fellows who are equipped with high power and full-size antennas. The "cliff-dweller" may not be able to "bore a hole" in the band as often, and as easily, but DX can be worked successfully when band conditions are suitable.

A 2 meter power amplifier

Presents a catalog of **QRP** transceivers, antenna tuners, and related accessories for amateur radio operators. The product line includes the ZM-2 antenna tuner, designed for efficient impedance matching across HF bands, and the NW-series QRP transceivers, offering low-power CW operation. Additionally, the site details various ladder line insulators and specialized connectors, emphasizing robust construction for field deployment and home station use. Each product listing provides specifications, operational parameters, and pricing information. Compares the features of different **QRP transceiver** models, such as the NW-40 and NW-20, highlighting their respective band coverage and power output capabilities. The ZM-2 tuner's performance is detailed with typical SWR reduction figures for various antenna types, demonstrating its utility for portable and fixed stations. Customer testimonials and product images illustrate the practical application and build quality of EMTECH's offerings, providing insights into their durability and ease of integration into existing amateur radio setups.

A little information about me and my equipment, loads of useful links to just about everything CB radio related. Features a tune-up section for just about every PLL controled radio out there. Drop by, you won't be disapointed!

Meter and Low Power Tune for FT-857D

Manufacturer of HF transceivers, antenna couplers, antennas, RF Power amplifiers, portable antennas, speakers and other accessories for 28 years.

We worry a lot about Standing Wave Ratio (SWR) in amateur radio since SWR is one indication of how well our antenna system is working. Most HF transceivers and antenna tuners have built in SWR meters. SWR is a measure of a transceiver' s output power verses the portion of that power reflected by the antenna system

A 144 MHz kilowatt amplifier project details the construction and performance of a high-power VHF linear using the GU74b tetrode. This Russian tube, equivalent to the Svetlana 4CX800, is noted for its conservative datasheet ratings, performing closer to 800-1000W anode dissipation in practical applications. The design prioritizes compactness and achieves 1.2 kW output with only 20W of drive power, demonstrating a 70% efficiency at 2.5 kV plate voltage. The amplifier has been successfully deployed in demanding _EME_ (Earth-Moon-Earth) operations since June 1994. Challenges encountered during development included achieving stability with a grid-1 input configuration. The author, _CT1DMK_, opted not to publish the full design due to its complexity, suggesting it might be difficult for less experienced builders to replicate successfully. However, he invites direct contact for those with specific interest in the design. Future plans include a "144MHz GS35b compact amplifier" project, promising another kilowatt-plus design. This resource offers insights into high-power VHF amplifier construction and the practical application of specific power tubes.

Manufacturer of big power amplifiers

Strong RF HF power amplifiers made in europe ! Output 2,5KW 4KW PEP, 160m to 10m.

This resource provides a historical listing of **unlicensed amateur radio beacons** active in the United States as of December 1993, specifically detailing both **LOWFER** (Low Frequency Experimental Radio) and **MEDFER** (Medium Frequency Experimental Radio) operations. The data includes beacon frequencies in kilocycles (Kc), identification codes, state locations, and the callsigns or names of the beacon operators. Frequencies range from 166.667 Kc for LOWFER to 1706.0 Kc for MEDFER, illustrating the spectrum utilized by these experimental stations. The information was originally compiled by Mark Burkart and relayed to the rec.radio.shortwave newsgroup by Rick Robinson, KF4AR. The list serves as a snapshot of experimental beacon activity from the early 1990s, offering insight into the types of operations and the individuals involved in unlicensed, low-power transmissions. It highlights specific beacon IDs like "ABC SC" on 510.5 Kc and "GK HI" on 1620 Kc, alongside operator details such as Todd Roberts (WD4NGG) and Herb Vanderbeek (WY6G). While not a current operational guide, it is a valuable historical document for those interested in the evolution of LF/MF experimental radio and the early days of internet-based amateur radio information sharing.

This circuit is unique in that it uses a power mosfet as a final rather than a conventional bipolar transistor.

Two types of home-brewed 12/20 Ampere 13,8volt power supplies, including detailed part lists by ON6MU

Australian dealer, HF linear amplifiers, power supplies, baluns, HF UHF yagis and verticals including multiband HF verticals.

Building a Dummy Load and Measuring Power Accurately by Ken, K4EAA

This article describes a low-cost, low-to-moderate power dummy load, which presents a 50-Ohm resistive load from HF through 440MHz.

Selecting an appropriate antenna system for shortwave broadcasting involves evaluating various types based on performance, cost, and operational parameters. This resource details the critical specifications for broadcast antennas, including average and peak power ratings, directivity, takeoff angle (TOA), horizontal beamwidth, and gain, emphasizing that a 100-kW transmitter requires an antenna rated for 150 kW average and 400 kW peak. It clarifies that low TOA signals travel thousands of kilometers, while high TOA is for local coverage, and nearly all modern shortwave broadcast antennas are horizontally polarized. The article explores specific antenna types, such as Log-Periodic Antennas (LPAs), which offer wide frequency ranges (e.g., 2-30 MHz) and directional patterns with 11 dBi gain, costing from $20K to over $100K for multi-curtain versions. Dipole arrays, also known as curtain antennas, are prevalent in international broadcasting, featuring steerable beams (±15° and ±30°) and mode-switching capabilities to alter TOA, with high/low pairs costing over $1 million. Fan dipoles are noted for omnidirectional patterns, smaller size, and lower cost for low-power applications, while rhombics, though simple, require resistive termination and incur several dB of I2R losses. Balun considerations are crucial, as most communications baluns are not rated for the higher average and peak powers of AM broadcast transmitters. Modern shortwave antennas utilize durable materials like Alumoweld wire rope for radiators and support elements, avoiding copper, fiberglass, or materials prone to stretching or deterioration. Feeder systems for high-power stations often require tapered-line baluns to convert 50-ohm unbalanced power to 300-ohm balanced for connection to the antenna.

A 13,8v/5Amp 78H05 based power supply for portable use. In this example used to power up a Yaesu FT-817

This homebrewed antenna tuning unit also incorporates a 50-ohm QRP dummy load, power meter (1 or 10 Watts full scale), and SWR meter

Dchematics and photos of a secure power supply (short-cut, Rf feedback, high voltage etc.) by iz7ath

This project uses a widely available IRF510 MOSFET, work on HF 80, 40, 30, 20 and 17 meter bands

This page describes the loading coil (inductor) that W8WWV built for my center-loaded 160 meter band (1.83 MHz) vertical antenna.

Database system with 60000 frequencies, powerfull 3D MUF/LUF-propagtion software and full copntrol of several receivers

Power and SWR Meter with dual bargraphs and sticky bar, using 2x AD8307

The most flexible and powerful Microwave and RF Filter and Multiplexer Design Software. Download Filpro-student.zip

Free windows program to calculate magnetic loop antenna.This small loop antenna calculator allow to determine capacitance and voltage based on Loop circumference, desired resonant frequency, conductor diameter and the operating power

Solid State and TWT Amplifiers From 1 MHz to 40 GHz with Power Levels from .1 mil Watt to 2.5 Kw

A KD1JV Melt solder kit, a swr and power meter operating from 160 to 6 meters ideal for portable and field use

This project shows how to build a 50-ohm dummy load using non-inductive resistors, oil for heat dissipation, and a simple assembly process. It enables accurate transmitter tuning, testing, and power measurement across LF to UHF bands. The setup allows meter calibration by measuring peak voltage, applying diode drop correction, and calculating RMS voltage and power precisely. Parts are inexpensive and widely available. With proper assembly, this dummy load offers extended service life, accurate readings within 2%, and a reliable alternative to costly commercial wattmeters for amateur radio applications.

Over 40 years of experience inform the reviews and commentary presented on Dave's Radio Receiver Page, covering a wide array of radio receivers and transceivers. The resource details specific models such as the **ICOM IC-R8600** SDR Communications Receiver, which is lauded as Icom's best wide-band receiver, even surpassing the IC-R9500 in performance. Other notable reviews include the ICOM IC-7300 HF Transceiver, highlighting its direct sampling SDR technology and spectrum scope capabilities, alongside numerous models from Japan Radio Co. (JRC), Kenwood, Yaesu, and various portable shortwave receivers. The content provides practical insights into the performance and characteristics of each radio, often drawing comparisons between models. For instance, the early issues with the AOR AR7030 receiver's Bourns mechanical encoders are thoroughly documented, including AOR's eventual switch to higher-quality Alps encoders. The page also features reviews of antennas like the MFJ-1026 Noise Canceling Signal Enhancer and various power supplies, offering a holistic view of radio monitoring setups. The author's "2 ear / 2 eye method" emphasizes real-world listening experiences over laboratory measurements, providing a unique perspective on equipment utility.

University of Texas Amateur Radio Club RF-Calculator. This is a main beam power density estimation program intended for use as part of a routine evaluation of RF safety compliance with FCC regulations

AEA Technology Inc. is a pioneer and leading manufacturer of RF and cable test equipment for the wireless, Telco, CATV, NMR & MRI, RFID, telemetry, aviation, commercial, military, and two-way radio industries. Produces SWR Meters, Pre Amplifiers, filters, power meters and antenna testing products

Crossed yagi for 437 MHz Satellite antenna, with power divider splitter build.

Antennas, base mobile scanner and vhf antenna, coax cables, coax switch, Lightning Arrestor, mounts, power supply, speakers and wattmeters

This is a C-L-C type tuner with a reflected power indicator. Tuning is done for minimum reflected power.

Ham Radio Antenna Tuners--Full Legal Power--Patented Circuit--Outstanding Efficiency and Power Capability

AM/FM/CW QRP RF Power Amplifier for the HF 10 or 11 meterband (28MHz/27MHz)

Radio Scanners Uniden Bearcat, Antennas, CB_Radios, Ni-Cad Batteries, Frequency Books, Accessories, Power Supplies and Cords, FM Two Way Radios, and other Related Merchandise

Constructing a **2-meter** J-pole antenna from readily available copper plumbing components offers a robust and cost-effective solution for VHF operation. This design, dubbed the "Plumber's Delight," functions essentially as a half-wave dipole fed by 50-ohm coax via a **gamma match**. It incorporates a quarter-wave copper tubing support, which, when affixed to a metal mast or tower, enhances forward power in the direction of the radiating elements. The original configuration utilized a small ceramic trimmer capacitor for the gamma match, suitable for up to 10 watts. A subsequent modification replaced this with a 50 pF variable capacitor housed in a plastic enclosure, accommodating higher RF power and improving weather resistance. The antenna elements are secured using a copper "T" fitting, and an SO-239 connector mounts directly to this fitting. Performance includes gain away from the support mast, and tuning is straightforward by adjusting the gamma match capacitor for a 1:1 SWR. The total cost for materials, excluding the capacitor and coax, can be under $10.

1500 Watt HF power amplifier

Unified Microsystems presents a range of amateur radio products, notably the **XT-4 MK2 CW Memory Keyer**, a battery-powered iambic keyer designed for portable operations like Field Day, POTA, SOTA, and DXpeditions. It features four non-volatile memories, each storing approximately 240 Morse characters, and operates at speeds from 8-45 WPM. The XT-4 MK2 also includes an auto power save function and paddle reverse, making it adaptable for multi-operator setups. Beyond the XT-4 MK2, the site details the **W9XT Contest Card**, a PC plug-in board offering DVK and CW interface capabilities, allowing operators to record and playback CQs and contest exchanges. Other offerings include the BevFlex-4X RX Antenna System, RAS-4 RX Antenna Switch, VK-64 Voice CW Keyer, and various USB interfaces. Additional products cover electronic development, such as the ATS-1 Terminal Shield for Arduino™ and VR-X Power Supply Voltage Regulators, demonstrating a broader scope beyond just operating accessories. The XT-4Beacon MK2 / CW IDer is also highlighted for beacon projects, capable of storing messages up to 5 minutes at 25 WPM.

Italian page including pictures schematics diagrams of an home made linear amplifier using four EL509 in parallel. Output power is about 700W.

Transmitter power limits and frequencies allocation by band

YU1AW project for a home made QRO PA 144 MHz 20 kW GU36B-1

Constructing a high-power solid-state amplifier for HF operations presents unique challenges, particularly when aiming for significant output like 600 watts. This project details an amplifier design employing **Motorola MRF150** FETs, a common choice for their robust performance in RF power applications. The design emphasizes achieving substantial power output, a critical factor for effective DXing and contesting, where every decibel can make a difference in signal propagation and readability. While specific circuit diagrams or construction details are not directly presented on the current page, the mention of MRF150 FETs points towards a design that would typically involve push-pull configurations, impedance matching networks, and robust power supply considerations to handle the high current demands. Such amplifiers are often built with an eye towards linearity and efficiency across the HF bands. Amateurs pursuing similar high-power solid-state projects often share insights on thermal management, intermodulation distortion, and component sourcing, all vital for a stable and reliable amplifier capable of delivering 600 watts into a proper antenna system.

Welcome to the web site of Wilson Antenna, Inc., manufacturers of the worlds most powerful CB antennas for the automobile and 18 wheel tractor rigs.

Based on VK5BR's Z-Match and designed for High RF Power covers 160 to 10 meters by VK6YSF

The homemade CW paddle key design, inspired by a QRP homepage, utilizes soldered PC board material for its construction. The builder, DL5NEJ, modified an existing design to achieve a smaller footprint, preferring a compact setup for portable operations. This paddle was specifically built to complement a Wilderness Radio SST20 QRP transceiver kit, demonstrating its suitability for low-power operations. The project details suggest a straightforward assembly process, with the primary components being readily available PC board scraps. The design emphasizes simplicity and functionality, aiming to provide a reliable keying experience comparable to commercial paddles like the Bencher. Performance evaluations indicated the simple paddle operates effectively, prompting further exploration into similarly minimalist QRP rig designs. Additional construction details for a similar paddle are available from PA0CMU.

Import/export of cb transceivers, antennas, speakers, power supplies, etc. Firestik, sirio, sadelta, hustler, boomerang, president, k-po, shakespeare, danita, k-40, wilson, midland