Advanced Qualification · A-003 Measurements · A-003-006-011

At what line impedance do most RF wattmeters usually operate?

1. A 100 ohms
2. B 300 ohms
3. C 50 ohms
4. D 25 ohms

Correct answer: C — 50 ohms. From the official ISED question bank, verified word for word.

Why

Most RF wattmeters are built to work with a standard line impedance of 50 ohms because this value offers a practical balance between power handling and signal loss for typical amateur radio equipment. The full explanation — and one for every question — is in Pro.

Practise this section

Measurements: meters, oscilloscopes, counters, signal generators, and what a reading actually tells you.

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