The CV5831 (commercially the EF183) is a high gain variable μ RF amplifier pentode. It is a late 1950s design and superseded the EF85. The EF184 was the straight version of the design and replaced the EF80. All four valves have the same pin connections.
In 1959 Mullard describe the EF183 as: a frame-grid variable-mu RF pentode for use as an automatic gain controlled IF amplifier in television receivers. The heater is suitable for series or parallel operation by AC or DC.
The valve performance figures are given at 40 MHz and the normal TV IF frequency was around 33 MHz.
Within the screen the anode can be seen as two small plates connected by a strap. The suppressor grid is an open pitch helix whereas the screen grid wires pass flat across either side of the cathode. The control grid is not visible.
Through the screen is one of the anode plates. Note the lower screen reaching to the glass foot.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 53 mm tall.
