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 It is a late 1950s design and superseded the EF85.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.
Through the mesh screen can be seen the open pitch suppressor grid and the tighter pitch screen grid. The strap joining the two parts of the anode is also clear. The inner grids pass flat across the cathode.
The anode strap on the left and the ends of the wire grids on the right.
The suppressor grid is an open helix whereas the screen grid is shaped to be flat as it passes over the cathode.
In this image the internal structure can be seen. The working part of the anode is placed either side of the cathode with a strap connecting the two parts. The suppressor grid is close to the anode and is formed by a very open wire helix. The visible inner grid is the screen grid and it has the wire passing flat across the control grid. The control grid is wound of very fine wire and passes flat across the face of the cathode.
A microscope image revealing the control grid wire. The thicker wire is that of the screen grid.
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 EF183 was first introduced in 1959. See also1959 adverts.
