XHRKO-FM (90.5 FM; 90.5 The Blaster) is a commercial FM radio station licensed to Tijuana, Baja California, Mexico and serving the San Diego–Tijuana area. It broadcasts an English-language Active Rock format aimed at San Diego listeners branded as 90.5 The Blaster. The station shares studios with Top 40/CHR station KRKB-FM in San Diego near the San Diego Convention Center and the transmitter is located on the Cerro Colorado hill in Tijuana. The station is owned by RKO Radio through the Tijuana-based XHRKO de Tijuana y San Diego, S.A. de C.V. company. The station is known as "The Last Border Blaster", being the last of the 1950s "border blaster" stations excluded from the FM radio border blaster ban to remain on the air as an primarily English-language station.
XHRKO-FM signed-on June 12, 1949 as XHTT-FM. The license was originally held by a Monterrey native by the name of Eduardo Tavárez-Tejedor (1920-1982). He leased the station to various American groups during the 1950s, which effectively made XHTT a border blaster.
In 1970, XHTT-FM was purchased by RKO General, allegedly as a tax dodge, who founded XHRKO de Tijuana y San Diego, S.A. de C.V. to operate the station under Mexican broadcasting rules. The callsign was changed to XHRKO-FM. The station continued with it's long-running Top 40 format, barring a brief switch to disco from 1979-1980.
From 1993-2005, XHRKO operated as a brokered programming station, mainly airing syndicated programs & radio infomercials, along with some Mexican radio programs to fill in time. The station gained it's current Active Rock format in 2006.