The 5U8 is a 9-pin miniature compound tube housing a medium-mu triode and a sharp-cutoff pentode in a single envelope. Designed for VHF local oscillator-mixer, sound IF, and video amplifier service in television receivers and radio front-ends, it operates on a 4.7V/600mA controlled warm-up series heater. It was regularly specified in late-1950s series-string chassis manufactured by RCA Victor, Zenith, Philco, and Sylvania. Available in NOS and tested used conditions.