ARRL Technician Practice Exam 2025 - Free Technician License Practice Questions and Study Guide

The correct choice highlights the means by which operators can input or select the desired operating frequency on a modern transceiver. Both the keypad and the VFO (Variable Frequency Oscillator) knob are primary interfaces for frequency selection.

Using the keypad allows for precise frequency entry, where operators can directly input the desired frequency using numbers. This is particularly useful for quickly accessing specific frequencies without the need to manually tune through the bands.

On the other hand, the VFO knob provides a tactile and intuitive way to adjust the frequency by manually rotating the knob. This is often preferred in operating scenarios where the operator wishes to fine-tune frequency settings or explore varying frequencies within a band.

The options regarding the antenna tuner, SWR meter, and power amplifier do not directly facilitate entering operating frequencies. The antenna tuner is used to match the impedance of the antenna system to the transceiver for optimal power transfer, the SWR meter measures the standing wave ratio to assess the efficiency of the transmission, and the power amplifier boosts the transmitted signal without affecting frequency selection. Thus, they serve specific functions in the signal transmission and reception chain but are not tools for entering operating frequencies.