Basic Qualification · B-008 Interference and suppression · B-008-003-010
Qu'est-ce qui peut provoquer des oscillations parasites dans un étage?
- AUne rétroaction négative indésirable
- BUne dérive de l'oscillateur
- CUne instabilité du bloc d'alimentation
- DUne rétroaction positive indésirable
Correct answer: D — Une rétroaction positive indésirable. Question tirée de la banque officielle d'ISDE.
Why
Parasitic oscillations happen when a tiny part of an output signal loops back into the input and gets stronger instead of weaker, which is exactly what unwanted positive feedback does. The full explanation — and one for every question — is in Pro.
Practise this section
Interference and suppression is section B-008 of the Basic exam: When things interfere: harmonics, overload, RFI to and from your station, filters, ferrites and how to fix the neighbour's TV.
Drill B-008 — free, no account