| Call Letter | Location |
| C | Moscow |
| D | Odessa |
| F | Vladivostok |
| K | Khabarovsk |
| L | St. Petersburg |
| M | Magadan |
| O | Moscow |
| P | Kaliningrad |
| R | Ustinov |
| S | Archangel |
| U | Murmansk |
| X | Prague |
| YU | Kholmsk |
| V | Tashkent |
They all provide a good propogation indicator for DX working on the 7Mhz Band