Homebrew W6JL 50 Watt Amplifier for 80-17m

This article details the construction of a homebrew 50-watt FET amplifier based on Don W6JL's design, which won the QST Homebrew contest in 2009. The amplifier is designed as an afterburner for QRP rigs like the FT817, providing a 12dB power lift. It utilizes IRFZ24N FETs and covers the 80, 40, 30, and 20-meter bands, with the 20m LPF extending to 17m. The author, VK3HN, describes building an 'artisan PCB' and housing the unit in an aluminum heatsink channel. Key technical details include a simple FT37-43 transformer for the input network, a 3dB pad relay-switched for lower bands (80m and 40m) controlled by an Arduino, and an RF-actuated T/R switch. The LPF board incorporates four relay-switched filters rated for 50 watts, using capacitors with a minimum 250VDC rating. The amplifier requires approximately 5 watts of drive power.