When selecting a CW transmitting frequency, what minimum separation from other stations should be used to minimize interference to stations on adjacent frequencies?
Why A CW signal keyed at typical speeds occupies only a couple hundred hertz of bandwidth, so stations can be packed closely together. Leaving roughly 150 Hz to 500 Hz between your transmit frequency and the next signal keeps both out of each other's receive filters, which are often set to 250 Hz or 500 Hz for CW. Less separation than that and the two notes fall inside the same filter passband and interfere.
Watch out The kilohertz-wide figures come from voice practice: 1 kHz to 3 kHz would be sensible spacing for SSB, whose signal is about 3 kHz wide, and 3 kHz to 6 kHz is even wider. Using that much room on CW wastes band space.
CW is narrow: think in hundreds of hertz (150-500 Hz). SSB is wide: think in kilohertz.