This exhibit is a Mullard ECL80 made on or after 1970 when the stylised logo appeared.
The ECL80 as primarily designed for use in television receivers (VHF 405 line models) with the triode as a frame blocking oscillator and the pentode as a frame output valve. Other applications include the use of the triode as a line blocking oscillator, AF voltage amplifier or in multi-vibrator circuits and the operation of the pentode as an audio output valve or a synchronising pulse separator. This valve was also used in low cost record players with high output crystal pick-ups, normally with a metal rectifier. The latter being an early solid state device.
The heater at 6.3 Volts and 300 mA makes this valve suitable for equipment with mains transformers and heater chains across the domestic mains.
The ECL80 was not without faults in use and the above article gives details.
The shielded rod on the left connects to the control grid of the triode behind the copper support of the pentode suppressor grid The latter has heat radiating fins on both supports.
The separation of the top rods can be better seen in this image.
The pentode suppressor grid support with bright radiating fin.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 58 mm tall.
References: Data-sheet & 1040. Type ECL80 was first introduced in 1950. See also1950 adverts.
