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