The EF86 is the standard early stage audio pre-amplifier valve. The EF86 is a low noise pentode intended for use as a RC coupled AF voltage amplifier, particularly in the early stages of high gain audio amplifiers, microphone pre-amplifiers and magnetic tape recorders.The screen is dimpled and not perforated.The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 48 mm tall.Reference: Data-sheet & 1040. Type EF86 was first introduced in 1953. See also 1953 adverts. |