Search results

Video, how to build a 130 Watt Dummy Load for HF amateur radio

This is a 200 Watt PEP step up transformer for end fed full and half wave antennas without radials, designed as a 200 Watt PEP

The 60 Watt linear amplifier is simple all solid state circuit using power mosfet IRF840.

G3WZT John Matthews project of a 600 Watt solid state linear amplifier for the 6 meters band

This project was published in the April 2004 issue of the Australian magazine Amateur Radio, and has been designed using parts which are very readily available.

This is the report of a MFJ-259B analysis of two 100 ohm / 5 watts resistors in parallel partially in italian

1 watt amplifier for 10 ghz made from surplus stuff

Conversion of Zetagi HP201 SWR wattmeter for HF Amateur Bands by G8ODE

A solid state linear based on EB104 Motorola Engineering Bulletin by Helge Granberg. It uses 4 MRF150 FETs in push-pull parallel to acheive 600 Watts from about 6 Watts drive

A VHF power amplifier made with two cheap RF transistors, 2N3924 as driver and a BFS22A for final stage, giving an unexpected output power of 7-8 watts maximum

Building a PEP Power circuit for all analogue watt-meter

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.

Engineering Solutions for Unique Problems. Manufacturer of high Voltage, high Current, high Power Power Supply

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 lower power desktop linear with integrated 120vac power supply. This, very compact, dual 811 version will deliver about 300 watts output. Covers all bands including WARC bands.

The UK amateur radio licensing scheme features three distinct tiers: Foundation, Intermediate, and Full, each granting specific operating privileges. For instance, the **Foundation Licence** permits a maximum of 10 watts output power on most allocated bands, with restricted band access. The Intermediate Licence allows up to 50 watts, while the **Full Licence** grants access to the maximum UK legal power limits and all available amateur radio band allocations. UK call sign prefixes and formats provide insights into the licensee's class and the approximate issuance date. For example, M3, M6, and M7 prefixes with three letters denote Foundation Licences issued from 2002, 2008, and 2018 respectively. Intermediate Licences, often starting with "2E0" or "2E1" followed by three letters, were issued from 1991 onwards. Full Licences encompass a broader range of prefixes like G2, G3, G4, G0, and M0, with varying letter counts indicating different historical license classes and issuance periods, such as G3 plus three letters issued between 1946 and 1971. Special prefixes like GB are reserved for repeaters, beacons, data mailboxes, and special event stations, with specific numerical sequences (e.g., GB3 for repeaters, GB7 for data repeaters/mailboxes) indicating their function. Optional prefixes such as GC, GD, GI, GM, and GW denote specific UK countries (e.g., Wales, Isle of Man, Northern Ireland, Scotland, England) and can also signify club stations.

Modification of the MHW 612 by Motorola for the two meter band by sv1bsx

This online guide details the microphone pinout for the Kenwood TR-7950 transceiver, specifically addressing the wiring configuration for a dynamic mobile microphone with a **500 Ohm** impedance. It provides a pin-by-pin breakdown for the 6-pin microphone connector, identifying the function of each active pin. The resource specifies that Pin #1 is for the microphone audio (white wire), Pin #2 controls the _PTT_ (black wire), Pin #3 activates the memory down function (blue wire), and Pin #4 controls the memory up function (red wire). Pin #6 is designated as the ground connection, while Pin #5 remains unused in this configuration. The document focuses on the physical wiring necessary to restore microphone functionality to the Kenwood TR-7950, a transceiver capable of **45 watts** output on the _2m band_. It directly addresses the technical challenge of re-establishing correct electrical connections after microphone wires have been disconnected from the connector. The information facilitates proper microphone operation for simplex QSOs and other voice communications. DXZone Focus: Online Guide | Microphone Pinout | Kenwood TR-7950 | PTT Wiring

2 meter kilowatt linear amplifier

The digital wattmeter project was created for the purpose of measuring power in the range of 300nw to 30w.

20 Watt Power Amp for Softrock or for QRP transceivers by M0RZF

High Voltage Dummy Load 3000 OHMS, 5400 WATTS There are 45 layers of 6 resistors, each one being 400 OHMS @ 20 Watts for a total of 270 resistors

A radio's transmitting power can be concentrated along the horizon by use of a GAIN antenna. Although you may still be transmitting with four watts of power, your effective radiated powerwill be greatly increased. This table shows the effects of antenna gain on a transmitter with 4 watts of transmit power.

A 40 meter rig with SSB and CW operating modes. This is a low power QRP rig with up to 6 watts CW or PEP output.

The 23 cm amplifier pictured here delivers more than 300 watts with 10 watts drive.

Plans and hex code for an RF wattmeter based on an Analog Devices AD8307 log amplifier.

The NCDXF/IARU International Beacon Project operates a worldwide network of 18 high-frequency radio beacons, continuously transmitting on 14.100, 18.110, 21.150, 24.930, and 28.200 MHz. These beacons, initially launched in 1979 with a single station and expanded to the current 18-beacon system in 1995, provide reliable signals for both amateur and commercial users to assess current **ionospheric propagation** conditions. The system's design, construction, and operation are managed by volunteers, covering hardware and shipping costs. The resource details the evolution of the beacon network, including the transition from Kenwood TS-50s transmitters to Icom IC-7200 radios with a new controller design implemented in 2015. It explains how listening for these 100-watt signals, transmitted to vertical antennas, allows operators to determine band openings and optimal propagation paths globally. The content also references three QST articles providing historical context and technical specifics of the beacon project. Practical information includes methods for identifying transmitting beacons via a schedule or specialized software like FAROS and Skimmer, which integrates with the **Reverse Beacon Network** for automated monitoring.

40 meters band 5 watts transmitter, uses a 6L6 with a 6X5 rectifier and a 0D3 voltage regulator tube on the screen.

Digital Vector Wattmeters, Dummy loads, software defined panadapter systems, SteppIR Tuning Relay, Digital SWR meters, LP-Pan Pan Adapter IQ Decoder for SDR based panadapter system

The DL4MEA Power Meter

The **United States Islands (USI) Awards Program** is an amateur radio operating activity centered on activating and chasing islands located within the fifty states of the United States, its territories, and protectorates. These islands encompass coastal shores, lakes, rivers, ponds, and streams, offering a diverse range of operating environments. The program provides numerous achievement awards for both island activators and island chasers, encouraging portable operations and mini-DXpeditions. Participants engage in year-round activities, including the **One-Day-Getaway (1DG)**, a casual portable operation held on the second Saturday of May, and the U.S. Islands QSO Party (IQP), a 15-hour contest occurring on the last full weekend of August. USI encourages hams to discover and operate from islands in their local areas, providing an alternative to traditional Field Day operations for outdoor radio enjoyment. The program supports various operating styles, including portable, walk-on, paddle-to, motor-to, mobile, and drive-on activations. Recent activities include AC1RH activating MA064R Eagle Island daily, aiming for over 100 activations using 600 watts, and KD9ZAB and KD5YZY qualifying MO021R Tower Rock, which is also a POTA US-10147 location. The USI program maintains a clear distinction from the Islands On The Air (IOTA) awards program.

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

The _Italian VHF Beacons_ resource provides a detailed listing of active and QRT amateur radio beacons operating across VHF, UHF, and SHF bands within Italy. Each entry specifies the beacon's callsign (e.g., IQ1SP/B), operating frequency (e.g., 144.411 MHz), QTH locator (e.g., JN44VC), effective radiated power (ERP) in watts, and antenna configuration (e.g., Big Wheel, 4x Dipole, Yagi). This data is crucial for radio amateurs involved in propagation studies, equipment testing, and long-distance (DX) communication on these higher frequency bands, offering fixed signal sources for monitoring. This compilation, last updated in October 2005, serves as a historical snapshot of Italian beacon activity. For instance, it lists several 144 MHz beacons with ERPs ranging from **0.1W** to **10W**, and higher frequency beacons such as I8EMG/B on 1296.880 MHz and I3EME/B on 24192.132 MHz. The inclusion of QRT (Quiet Radio Teletype) status for many entries indicates the dynamic nature of beacon operations over time. Users can utilize this information to identify potential signal sources for band openings or to calibrate their receiving equipment against known transmissions.

Meter capable of accurately measuring low levels of RF power

Bird wattmeters and extras accessories

The Rock-Mite is a 40m CW kit offered by Small Wonder Labs . It features built-in keyer, direct conversion receiver with a crystal RF bandpass filter, 500 milliwatts of power, and switchable frequency offsets to work around QRM

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.

This is a SSB and CW transceiver for the 80m and 20m bands. It produces 25 Watts out and uses a digital frequency display.

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.

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

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'.

A circuit for a 5 milliwatts super QRP morse code transceiver by VE2ZAZ

A 50-ohm generator feeding a 50-ohm line connected to a _quarter-wave transformer_ (150 ohms) terminated in a 450-ohm load is analyzed to understand transient behavior. The paper meticulously tracks voltage and current waves, reflection coefficients, and power levels through a sequence of events, starting from quiescent conditions. It details how incident and reflected waves combine and interact at impedance discontinuities, illustrating the dynamic changes in impedance and SWR at various points in the system. The analysis reveals that the impedance at the interface between the 50-ohm line and the 150-ohm transformer changes from 150 ohms to **64.3 ohms** after the first reflected wave arrives. Subsequent reflections cause the impedance to asymptotically approach 50 ohms, reaching **53.22 ohms** after five wave terms. The study also examines the generator's reaction to transient SWR changes, noting that a 3:1 SWR can temporarily reduce generator output to 0.75 watts, but these effects are temporary and diminish as the system approaches steady-state conditions.

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.

A bycicle ham radio station setup, with full band coverage

The BP-3 was a valve-based spy radio transceiver, developed during WWII by Tadeusz Heftman of the Polish Military Wireless Unit in Stanmore (UK). It was introduced in 1943 and was intended for use by Agents and Resistance Organisations in Europe. The transmitter produces an output power of 50 Watts in CW

Demonstrates the operational status and reception reports for the SK6RUD/SA6RR QRPP beacons, which transmit on 478.9 kHz, 1995 kHz, 10.131 MHz, and 40.673 MHz. These beacons utilize extremely low power, with the 630-meter beacon operating at approximately 0.1 watt ERP into an L-antenna, showcasing the potential for long-distance contacts under favorable propagation conditions. The site details the specific frequencies and antenna types employed, such as a vertical at 500 kHz and a 1/4 vertical for higher bands. The resource compiles over 10,530 reception reports from amateur radio operators worldwide, logging details such as date, time, band, RST signal report, locator, distance, and receiver setup. Notable long-distance reports include a 500 kHz reception by AA1A-Dave from 5832 km in 2008 and a 10.133 MHz reception by ZL2FT-Jason from 17680 km in 2010, illustrating the global reach of these low-power transmissions. Each log entry provides specific equipment used by the reporting station, including transceivers like the Yaesu FT817, ICOM IC-7300, and various antenna configurations such as coaxial mag loops, inverted Ls, and end-fed wires. The primary objective of the SK6RUD beacons is to challenge conventional notions of power requirements for effective two-way communication, proving that contacts over significant distances are achievable with minimal output. The site also includes a submission form for new reception reports, fostering community engagement and continuous data collection on propagation phenomena across different bands. The detailed logs offer practical insights into real-world propagation characteristics and the efficacy of QRPP operations.

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

10.100 - 10.140 MHz 3 Watts output by 7n3wvm