Ham Amateur Radio Technician Practice Exam

How much change in signal strength is typically represented by one S unit?

1. 3 dB

2. 6 dB

3. 10 dB

4. 12 dB

The correct answer is: 6 dB

One S unit represents a change of 6 dB in signal strength. The S meter on a receiver indicates the strength of the incoming radio signal, and it is calibrated to show that every increase of one S unit corresponds to a doubling or halving of the signal power. This relationship is based on logarithmic calculations, where a change of 3 dB represents a doubling of power, thus moving from one S unit to another entails a total change equivalent to a 6 dB difference. This principle is crucial for radio operators as it helps them assess the strength of their signals during operations and understand how various factors can affect communication quality.