The 6HZ6 from RCA was designed as a sound detector for FM radio and FM inter-carrier TV sound. It is a dual control sharp cut-off pentode. The suppressor grid is close wound as can be seen through the notch in the outer screen.
The 5HZ6 differs only in heater requirements - 4.75 Volts at 600 mA. Both have standard US series heater chain current ratings.
The remains of the paint saying Made in USA and the RCA logo.
Another view of the suppressor grid.
The thin glass tube envelope is 18 mm in diameter and, excluding the base pins, is 46 mm tall.
References: Data-sheet. Type 6HZ6 was first introduced in 1963. See also1963 adverts.
