The CV5810 (commercially the EF184) is a high gain frame grid pentode. The EF184 superseded the ubiquitous EF80. The mutual conductance is 15.6 and the closely related (pin compatible) variable μ pentode EF183 has a μ of 12.5.
The valve is a sharp cut-off pentode for use as an IF amplifier in television receivers. This implies a relatively wide band function at about 33 MHz. The high mutual conductance was important for wide band width amplifiers. The CV version was probably used for radar signal amplification as well as monitors.
Looking through the mesh screen there are three wire grids and an anode made as two small rectangles joined by a strap, thus only active in a direct line from the cathode.
Here with some back lighting the anode shape becomes clear. The open pitch suppressor grid and the screen grid wires are seen but not the control grid. The latter is formed of very fine wire at a close pitch and very close to the face of the rectangular cathode. The pitch is much finer than the screen grid.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 54 mm tall.
