San Antonio got its first taste of California hard rockers Tesla when the band supported Def Leppard at the legendary HemisFair Arena on November 16, 1987. At the time, Tesla — who will appear Wednesday, June 5 at the Aztec Theatre — was supporting its debut LP, Mechanical Resonance, which included “Modern Day Cowboy.” The single featured Tesla’s signature strong songwriting, powerful riffs and the raspy, high-register vocals of one Jeff Keith.