The EF89 is a miniature RF voltage amplifier. Mullard describe the EF89 as a variable μ pentode for use as an RF or IF amplifier in FM/AM receivers and is designed to work with a tuned anode circuit.
Through the screen can be seen the open pitch suppressor grid plus the two inner grids. The anode is two small plates set either side of the cathode.
The width of the anode can be about half the width of the glass tube or 10 mm.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 53 mm tall.
References: Data-sheet & 1040. Type EF89 was first introduced in 1954. See also1954 adverts.
