The E80CF is a special quality triode pentode designed to withstand vibration in service. The pentode is aimed at mixer or RF or AF amplifier applications. The triode is designed for use as an oscillator at up to 300 MHz. Additionally the valve is designed to withstand long periods in cut-off - useful for computer applications.The main picture shows that this valve was made in Germany before re-unification.
The small triode is seen on the right. Note the screen extending below the lower mica.
The pentode is mounted with the grid axis at right angles to that of the triode. Within the anode part of the suppressor grid can be seen.
Thanks to John Sykes for sending the photographs.
The thin glass tube envelope is mm in diameter, and excluding the base pins is mm tall.
Reference: Datasheet. Type E80CF was first introduced in 1958.