The EF70 miniature pentode has a separate connection to grid 3.
Mullard describe the EF70 as a subminiature high slope RF pentode with a short suppressor grid base. A diode is connected internally to prevent this grid locking at a positive potential.
The internal diode can be seen on top of the top mica.
The wire grids can be seen through the gaps in the anode. The diode section is to the right.
Another view through the anode to the grids.
The B8D flying lead base. Mullard state that soldering must be at least 5 mm from the seal and that any bending of the leads must be at least 1.5 mm from the seal.
The thin glass tube envelope is 9 mm in diameter, and excluding the base pins is 37 mm tall.
References:Data-sheet & 1040 Type EF70 was first introduced in 1950. See also1950 adverts.
