Basic Qualification · B-003 Station assembly, practice and safety · B-003-018-010
Before checking a fault in a mains-operated power supply unit, it would be safest to first:
- Aremove and check the fuse from the power supply
- Bturn off the power and unplug the power cord
- Cshort out the leads of the filter capacitor
- Dcheck the action of the capacitor bleeder resistance
Correct answer: B — turn off the power and unplug the power cord. From the official ISED question bank, verified word for word.
Why
Mains electricity can deliver a lethal shock even when a device is switched off, so the only safe first step is to turn off the power and unplug the power cord to physically disconnect the unit from the wall outlet. The full explanation — and one for every question — is in Pro.
Practise this section
Station assembly, practice and safety is section B-003 of the Basic exam: Building a station safely: power supplies, grounding, RF exposure, lightning, feedline routing, and what a transmitter, receiver and transceiver actually do.
Drill B-003 — free, no account