Abkürzungen "U"
| UARL | Ukrainian Amateur Radio League  |
| UBA | Royal Union of Belgian Radio Amateurs |
| UCC | Ukrainian Contest Club |
| UCFA | Ukraine Castles and Fortress Awards |
| UDRA | Union Dominican de Radioaficionados |
| UDXT |
Ukrainian DXpeditioners Team |
| UFFA |
Ukrainian Flora & Fauna Awards |
| UFT | Unión Francaise des Telegraphistes |
| UKEICC | United Kingdom and Ireland Contest Club |
| UNARAF |
Union Nationale des Aveugles Radio-Amateurs de France |
| UNMISS | United Nations Mission in South Sudan |
| URA | Union de Radioaficionats Andorrans |
| URDA | Ukrainian Districts Award |
| URE | Unión de Radioaficionados Españoles |
| USi | United States Islands Awards |
| USKA | Union Schweizerischer Kurzwellen-Amateure |
| USN |
U.S. Navy et Antartiques Francaises |
