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This resource details the construction and performance of a compact broadband magnetic loop antenna designed for portable receiving applications with devices like the _ATS MiniRadio_. The antenna utilizes approximately 3 meters of 0.5–1 mm copper wire wound in two turns on a rhomboidal wooden frame, measuring 50 cm by 70 cm. It connects via a modified 9:1 unun, where the primary center tap is isolated from ground to improve common-mode noise rejection. The design provides untuned operation across a frequency range from the longwave band up to approximately 25 MHz. Performance characteristics include observable directivity for noise suppression and the ability to connect directly to a radio or via a 50 coaxial cable for remote operation. The article specifies the unun's 3:1 turns ratio and its SMA output for connectivity. The methodology focuses on practical construction and observed reception quality.

This article describes the design and construction of a 4-meter band vertical sleeved dipole antenna, built to complement a newly acquired Yaesu FTDX10 transceiver. The simple yet effective antenna consists of modified coaxial cable housed in weather-resistant plastic conduit, featuring an integrated 8-turn choke coil. Despite common misidentification as an EFHW antenna, this design is actually a sleeved dipole that provides an excellent 50-ohm match across the band, achieving SWR values between 1:1 and 1.1:1. The project demonstrates an economical approach to entering the relatively quiet 4-meter band.

The project details the construction of a small, portable **CW decoder** built around an Arduino Nano and an LM567 tone decoder circuit. It integrates an OLED display for output and is powered by a 1200 mAh Li-Po battery. The Arduino Nano is programmed with a modified version of the OST Morse Box firmware, originally based on Budd, WB7FHC's work, provided as a HEX file for flashing. The LM567 output connects to Arduino pin D2, while pins A6 and A7 are grounded due to the absence of potentiometers, simplifying the circuit. Standard I2C connections are used for the OLED: SDA to A4 and SCL to A5. The entire assembly, including the Arduino, OLED, and decoder circuit, is mounted on a perfboard to fit precisely within an old cassette tape box. This design emphasizes portability and compact form factor. Parameters for the decoder can be adjusted using a dedicated Windows Control program, offering flexibility in operation. The resource provides practical insights into adapting existing firmware for specific hardware constraints and achieving a self-contained, battery-powered **Morse code** decoding solution.

The project details the construction of a GM3OXX OXO transmitter, designed to accommodate **FT-243 crystals** using 3D-printed FX-243 holders from John KC9ON. It presents specific frequency adjustments, noting a 7030 KHz HC-49/s crystal could be tuned from 7029.8 KHz to 7031.7 KHz with an internal 45pF trimmer capacitor. The build incorporates a modified keying circuit to prevent oscillator run-on key-up and includes a TX/RX switch for sidetone via a connected receiver, with the transmitter output routed to a dummy load on receive. Practical construction aspects are thoroughly covered, including the process of cutting a rectangular opening in a diecast enclosure for the FT-243 socket and the selection of a **low-pass filter** (LPF) based on the QRP Labs kit, derived from the W3NQN design. The author achieved approximately 800mW output power from a 14.75V supply, measured with an NM0S QRPoMeter, using a 16.5-ohm emitter resistor in the 2N3866 final stage. The article also touches upon the potential for frequency agility across the 40M band using multiple FX-243 units with various crystals. The narrative includes a brief diversion into Bob W3BBO's recent homebrew projects, such as his Ugly Weekender MK II transceiver, highlighting the enduring appeal of classic QRP designs. The author reflects on the personal satisfaction derived from building RF-generating equipment, irrespective of DX achievements, and shares experiences of making local contacts with the 800mW OXO transmitter on 40 meters.

This resource details **cooling modifications** for Ameritron AL82, AL1200, and AL1500 HF amplifiers, specifically addressing heat issues encountered during high-duty-cycle digital mode operation. The author, WD4NGB, observed excessive heat in the tank area and band switch on an AL82, attributing it to insufficient exhaust over the 3-500 tubes and a complete lack of exhaust over the tank area. The modifications aim to prevent common failures such as damaged band switches and deformed insulating materials by increasing airflow and exhaust area. The page describes adding five holes to the chassis for enhanced cooling to the band switch and tank area, alongside enlarging the exhaust area over the inner 3-500 tube and the tank area on the amplifier cover, utilizing expanded metal for safety and RF shielding. The original cover featured 26.25 square inches of exhaust; the modified version significantly increases this to 48.5 square inches over the tubes and introduces an additional 15 square inches over the band switch. These changes are intended to resolve heating problems encountered during heavy, 100% duty cycle use in modes like RTTY or long SSB contests, which typically generate substantial heat. The article also discusses upgrading to a higher output fan, such as the G2E085-AA05-21, and modifying tube sockets for improved airflow and reduced back pressure, citing Tom Rauch (W8JI) of CTR Engineering as a source for parts.