The EC88 is a UHF triode designed for service as a grounded grid amplifier in Band IV and Band V television receivers. The upper part of Band V extends to almost 1,000 MHz.
Like similar valves the noise figure was kept low by operating at a significant anode current.
The dark U channel on the right is the anode. In the centre is the cathode and the double sided control grid. The format of the grid is two sturdy side supports braced top and bottom. It is a frame grid but not formed on a flat plate.
This image is taken looking at the back of the cathode. The fine grid wires passing across the un coated back of the cathode are too fine to be seen.
The anode on the left with the side of the frame grid in the centre.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 42 mm tall.
References: Data-sheet, 1040 & 1043. Type EC88 was first introduced in 1961.