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NCDXF/IARU beacons on 21150 kHz: the 15 m band checked every three minutes
The eighteen worldwide beacons on 21150 kHz, twenty seconds behind their slot on 20 m. A daytime band that depends on the sun: when the distant callsigns and all four dashes come through, 15 m is wide open.
What you hear
The same chain as in the main article: a callsign in Morse, four dashes stepping down from 100 watts to a tenth of a watt, a new beacon every ten seconds, the full round in three minutes. On 21150 kHz each beacon transmits twenty seconds after its slot on 14100 kHz, so 4U1UN opens the cycle at twenty seconds past the top of every third minute.
Who transmits and why
The Northern California DX Foundation with the IARU, from the same eighteen sites. 15 m was included because it is the first of the classic daytime bands: it depends heavily on the sun, and a beacon chain on it shows the difference between a good day and a dead one within a single three-minute round.
When and where to listen
Daylight, and the better the solar cycle, the longer the day. From Europe the band opens to Asia and the Indian Ocean in the morning, to Africa around midday and to the Americas from the afternoon until after sunset; in a solar maximum it can stay open to South America late into the evening. In winter at a solar minimum 21150 may carry nothing but OH2B and CS3B. Sporadic E in early summer sometimes brings a nearby beacon up with surprising strength for an hour.
In ShackDeck
Station catalogue → Beacons → NCDXF beacons 15 m. The program picks a public receiver that covers 21150 kHz, tunes it in CW and shows the waterfall; no receiver, antenna or account of your own is needed.