Basic Qualification · B-004 Circuit components · B-004-001-005
Typiquement, quelle gamme de fréquences l'amplificateur microphonique d'un émetteurrécepteur du service de radioamateur accepte-t-il?
- ADe 40 Hz à 40 000 Hz
- BDe 300 Hz à 3 000 Hz
- CDe 3 Hz à 300 Hz
- DDe 300 Hz à 1 000 Hz
Correct answer: B — De 300 Hz à 3 000 Hz. Question tirée de la banque officielle d'ISDE.
Why
Human speech contains most of its intelligible information between 300 hertz and 3 000 hertz, so the speech amplifier in a transceiver is designed to boost only this specific range to ensure clear communication while filtering out unnecessary noise. The full explanation — and one for every question — is in Pro.
Practise this section
Circuit components is section B-004 of the Basic exam: The parts inside the box: resistors, capacitors, inductors, diodes, transistors, tubes and what each does in a circuit.
Drill B-004 — free, no account