Sensibly equivalent¶ to:
The Cossor 6BX6 is equivalent to the Mullard EF80 but here we have an EF80 with no other identification than a plus sign.
Comparison with other EF80's reveals that the matching construction is that of Cossor's version and the green paint is distinctive.
Electrically the EF80 is an internally screened pentode and was a workhorse of the VHF TV receiver and was much used for RF, IF, and video amplification in 405 line television receivers.
The screen is typical Cossor and so are the mica's.
The thin glass tube envelope is 20 mm diameter and excluding the B9A base pins stands 59 mm high.
References: Datasheet & 1040 Type EF80 was first introduced in 1950.
Absolute Maximum Operating Conditions¶
Updated February 12, 2016. shape:thin.glass.tube construction:all.glass type:pentode age:1950.1960 base:b9a heater:6.3v pins:9 pin:1.k pin:2.g1 pin:3.k pin:4.h pin:5.h pin:6.s pin:7.a pin:8.g2 pin:9.g3