I have a chance to DX now QSO? It's worth calling me on the band "CQ DX"? And on which band? If you want to have some idea of your options on radio amateur bands, or you are just planning tactics for an upcoming race, it pays to know what is happening in the ionosphere right now. The range table by season and frequency can also help.
Typical spread during the spring and summer months | ||||||||
| Frequency kHz | 4000 | 4000 | 8000 | 8000 | 12000 | 12000 | 15000 | 15000 |
| Hours after sunset | Min | Max | Min | Max | Min | Max | Min | Max |
| 1 | 80 | 400 | 300 | 1500 | 800 | 5500 | 1200 | 10000 |
| 2 | 160 | 1000 | 400 | 2500 | 800 | 5500 | 1200 | 10000 |
| 3 | 160 | 1000 | 400 | 3000 | 800 | 5500 | ||
| 4 | 160 | 1280 | 400 | 4000 | ||||
| 5 | 160 | 1500 | 400 | 4000 | ||||
| 6 | 160 | 2500 | 650 | 5000 | ||||
| 7 | 160 | 2500 | 800 | 5500 | ||||
| 8 | 400 | 3000 | 1200 | 6500 | ||||
| 9 | 400 | 4000 | 1200 | 6500 | ||||
| 10 | 400 | 4000 | 1200 | 6500 | ||||
| 11 | 400 | 1500 | 800 | 4000 | ||||
| Hours after sunrise | Min | Max | Min | Max | Min | Max | Min | Max |
| 1 | 160 | 800 | 650 | 3000 | ||||
| 2 | 0 | 160 | 650 | 3000 | ||||
| 3 | 0 | 160 | 400 | 2500 | ||||
| 4 | 0 | 160 | 400 | 2500 | 800 | 1500 | ||
| 5 | 0 | 160 | 400 | 2500 | 800 | 2500 | ||
| 6 | 0 | 160 | 400 | 2500 | 800 | 4000 | 1200 | 6500 |
| 7 | 0 | 160 | 400 | 2500 | 800 | 5500 | 1200 | 6500 |
| 8 | 0 | 160 | 400 | 2500 | 800 | 5500 | 1200 | 6500 |
| 9 | 0 | 160 | 400 | 2500 | 800 | 5500 | 1200 | 6500 |
| 10 | 0 | 160 | 400 | 2500 | 800 | 5500 | 1200 | 6500 |
| 11 | 0 | 160 | 800 | 800 | 800 | 5500 | 1200 | 10000 |
| 12 | 0 | 300 | 800 | 800 | 800 | 5500 | 1200 | 10000 |
| 13 | 80 | 400 | 1200 | 1200 | 800 | 5500 | 1200 | 10000 |

Typical spread during autumn and winter months | ||||||||
| Frequency kHz | 4000 | 4000 | 8000 | 8000 | 12000 | 12000 | 15000 | 15000 |
| Hours after sunset | Min | Max | Min | Max | Min | Max | Min | Max |
| 1 | 160 | 1000 | 650 | 3000 | 800 | 5500 | 1200 | 10000 |
| 2 | 160 | 1280 | 650 | 3000 | 800 | 6500 | 1200 | 10000 |
| 3 | 160 | 1500 | 650 | 3000 | 800 | 6500 | ||
| 4 | 160 | 1500 | 650 | 4000 | 800 | 6500 | ||
| 5 | 160 | 1500 | 650 | 5000 | 800 | 6500 | ||
| 6 | 160 | 2500 | 650 | 5500 | ||||
| 7 | 400 | 3000 | 650 | 6500 | ||||
| 8 | 400 | 4000 | 800 | 6500 | ||||
| 9 | 800 | 5000 | 800 | 6500 | ||||
| 10 | 800 | 6500 | 800 | 6500 | ||||
| 11 | 800 | 5000 | 1200 | 8000 | ||||
| 12 | 400 | 4000 | 1200 | 8000 | ||||
| 13 | 400 | 2500 | 800 | 4000 | ||||
| Hours after sunrise | Min | Max | Min | Max | Min | Max | Min | Max |
| 1 | 160 | 1500 | 650 | 3000 | ||||
| 2 | 160 | 800 | 650 | 3000 | ||||
| 3 | 0 | 160 | 650 | 3000 | 5500 | 1200 | 6500 | |
| 4 | 0 | 160 | 650 | 3000 | 800 | 5500 | 1200 | 6500 |
| 5 | 0 | 160 | 400 | 2500 | 800 | 5500 | 1200 | 6500 |
| 6 | 0 | 160 | 400 | 2500 | 800 | 5500 | 1200 | 6500 |
| 7 | 0 | 160 | 400 | 2500 | 800 | 6500 | 1200 | 8000 |
| 8 | 0 | 160 | 400 | 2500 | 800 | 6500 | 1200 | 8000 |
| 9 | 0 | 160 | 400 | 2500 | 800 | 6500 | 1200 | 10000 |
| 10 | 0 | 160 | 400 | 1500 | 800 | 5500 | 1200 | 10000 |
| 11 | 0 | 400 | 400 | 2500 | 800 | 5500 | 1200 | 10000 |
You can read about the spread on KV, for example, in Milan OK1IF's article Chcete vyhrávat v contestech? Máte jen „pádlovku“? Jak si vybírat závodní kategorie? , OM4Q Monitoring of propagation conditions whether SW for propagation conditions on KV , How to measure antenna quality? a Disappointing forecast of propagation conditions
