15 meters needs less solar energy than 10 to refract, but still enough to skip a long way. At a flux of 115 it is the most reliable long-distance daylight band you have.
WHY THE SWEET SPOT WHEN THE SUN IS MODERATE
15 meters needs less solar energy than 10 to refract, but still enough to skip a long way. At a flux of 115 it is the most reliable long-distance daylight band you have.
It opens once the sun has had a couple of hours to work on the ionosphere, and it closes shortly after sunset when that ionisation starts to decay.
The hour either side of sunset is the good one — the grey line, where the absorbing layer has died but the refracting layer has not.
WHEN IT WORKS
BEST · Midday, and the hour around sunsetWORST · NightWATCH · Grey line, both ends of the day
WHO MAY TRANSMIT WHERE · 47 CFR §97.301
FREQUENCY (MHz)
MODE
LICENSE CLASS
21.000–21.025
CW
Extra
21.025–21.200
CW — Novice & Technician
Technician and above, General, Advanced, Extra
21.200–21.225
Voice
Extra
21.225–21.275
Voice
Advanced, Extra
21.275–21.450
Voice
General, Advanced, Extra
Is 15 meters open right now? The Ham Radio IQ app shows the MUF and LUF over your head this minute, whether this band is above or below them, and a map of real contacts being heard worldwide. See the board →