Save Your Tuner for Two Pence

摘要

Given the choice of circuits suitable for HF antenna tuning, would you sensibly choose a T network? The T network is renowned for suffering from low power transfer efficiency when compared with typical tuned transformer circuits. As usually configured, with a shunt inductor, it also fails to provide protection against the harmonics that inevitably accompany the output of our transmitters. Arguably this is not a function of an ASTU, but a function of the transmitter, although in the past when TV used lower frequencies many amateurs relied on their tuner for the last 'ounce' of harmonic suppression.