by R. Jayaraman (VU2JN) This note describes a compact Antenna Tuning Unit (ATU) that I assembled recently. It is capable of handling the full 100-watt output of my FT-840 transceiver. For efficient radiation of the RF power otput of a HF transmitter, its output impedance, the characteristic impedance of the transmission line (usually coaxial cable),… Continue reading A compact ATU handles 100 watts