Basic Qualification · B-005 Basic electronics and theory · B-005-008-011
A local amateur radio operator reports receiving your 100-watt 2-metre simplex transmission with an S-meter reading of "30 dB over S9." What power could you use to reduce that reading to S9?
- A 1 W
- B 10 W
- C 33.3 W
- D 0.1 W
Correct answer: D — 0.1 W. From the official ISED question bank, verified word for word.
Why
To drop a signal from 30 dB over S9 down to just S9, you must reduce the power by exactly 30 decibels. The full explanation — and one for every question — is in Pro.
Practise this section
The theory: Ohm's law, power, series and parallel circuits, AC and DC, frequency and wavelength, decibels, and the metric prefixes the exam leans on.