Question
When selecting a CW transmitting frequency, what minimum separation from other stations should be used to minimize interference to stations on adjacent frequencies?
Answer Options
- A) 5 Hz to 50 Hz
- B) 150 Hz to 500 Hz
- C) 1 kHz to 3 kHz
- D) 3 kHz to 6 kHz
Correct Answer: B
Explanation
Continuous Wave (CW), or Morse code, is a narrow-band mode, typically only requiring a bandwidth of around 150 \text{Hz} to be intelligible. However, to account for the necessary filter bandwidths and the natural spread of a keyed signal, a minimum separation of 150 \text{Hz} to 500 \text{Hz} is generally recommended when selecting a CW transmitting frequency away from other ongoing contacts.
Using at least a 150 \text{Hz} separation allows the adjacent stations to operate comfortably without their signal overlapping into the essential bandwidth of your receiver’s filter. Using a wider separation, up to 500 \text{Hz} or more, is considered excellent practice as it ensures the signals do not interfere with the receiving filters of older or simpler equipment.
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