K6AA

K6aa is a United States amateur radio callsign format used to identify licensed operators on the air. It is composed of a prefix that begins with K, followed by the numeral 6, and a two-letter suffix, in this case AA, producing K6AA. Callsigns like K6AA are issued by the Federal Communications Commission (FCC) and are registered to individual operators or stations.

In the US callsign system, the middle digit (the 6 in K6AA) denotes a geographic or regional district as defined by the FCC and the ARRL. While the digit is commonly associated with a particular area—often the western United States—the exact mapping is defined by regulatory authorities and can vary over time. The two-letter suffix, AA in this example, may be part of a standard issue sequence or a vanity choice. Vanity callsign options allow licensed operators to request specific letter combinations, subject to availability and regulatory rules.

On-air usage, operators must identify themselves with their callsign at the beginning and end of transmission and at designated intervals during activity. The callsign functions as the station’s official on-air identity and is used in station logs, contact records, and contest or DXpedition reporting.

Origin and format of US callsigns trace back to early 20th-century international and national regulations governing radiotelegraph and radio communications. The current practice allows a wide range of combinations, with prefixes, digits, and suffixes crafted to accommodate thousands of licensed operators. K6AA, as a representative example, illustrates how a western-United States callsign can appear in everyday amateur radio activity.