A communications receiver has four filters installed in it, respectively designated as 250 Hz, 500 Hz, 2.4 kHz and 6 kHz. You are copying a CW transmission and there is a great deal of interference. Which one of the filters would you choose?

Why

CW signals, which are Morse code tones, are very narrow in frequency, so a 250 Hz filter blocks the widest range of unwanted noise and interference while letting the signal through. 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.

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