ARRL Technician Practice Exam

What does a dummy load consist of?

1. A non-inductive resistor and a heat sink

2. A capacitor and a transformer

3. A variable resistor and a relay

4. A ceramic insulator and a diode

The correct answer is: A non-inductive resistor and a heat sink

A dummy load is a device used in radio communications to simulate an antenna without actually transmitting a radio signal. It is designed to dissipate power from a transmitter in a controlled manner, allowing for testing and tuning of the transmitter without radiating RF energy. The composition of a dummy load typically includes a non-inductive resistor. This type of resistor minimizes the inductance effect that could distort the signal when high-frequency signals are present. The non-inductive aspect is crucial to ensure that the load behaves accurately like an antenna across a wide frequency range. In addition to the resistor, a heat sink is often used to manage the heat generated by the resistor due to power dissipation. This is important, as large amounts of power can be applied during testing, and without proper heat management, the resistor could overheat and fail. The other options do not fit the functionality of a dummy load. Capacitors and transformers are more commonly used in tuning circuits and signal coupling but do not serve the same purpose as a dummy load. Variable resistors and relays may find application in other radio functionalities but are not components of a dummy load. Similarly, ceramic insulators and diodes have very different roles in radio circuits than that of simulating an antenna load.