100 W, 7–55 MHz Broadband Class‑AB RF Power Amplifier for Yaesu FT‑818 with 50 Ω I/O, 13.8 V/15 A Supply, Relay T/R Switching, PTT/ALC Interface, Selectable 5th‑Order Chebyshev LPF Bank, and Overtemperature‑Controlled Fan Support

Multi-device wireless control system using a Seeed Studio XIAO ESP32-C3, 433 MHz ASK receiver, 5 V relay drivers, AMS1117-3.3 regulator, input protection, and PCB isolation between low-voltage control and relay output sections.