It’s happening Saturday in Redwood City: For the first time ever, you can hear the classic rock of Journey, Santana and Steely Dan live — in one tribute extravaganza of a concert. In real life, these bands never would have played together: Journey came out of Santana, and Steely Dan didn’t perform live shows for 19 years, says Frank Parise, percussionist for Caravanserai, the Santana tribute group. The other bands in the lineup: Journey Unauthorized and Aja Vu. As the show’s promoters say: “When the lights go down in the city, check out the evil ways of Babylon sisters by getting tickets for the rockin’ tribute extravaganza.” The show is at 8 p.m.; the Fox Theatre is at 2209 Broadway. Tickets are $16 to $20. Call (650) 369-4119 or visit www.foxdream.com.