The CV1698 is an amplifier tetrode with a μ of 4.6 mA/V and an unusual heater rating. It is a UK Post Office design known as the POVT148 or VT no. 48.
Side view and getter carrier.
Some of the inner structure is just visible. It has a wide flat oxide coated cathode and is indirectly heated. The screen grid is close wound with fine wire.
The control grid connects to the top cap and the grid supports have cooling fins.
Thanks to Charlie Frazer for sending this exhibit all the way from New Zealand.
The classic envelope is 41 mm in diameter, and excluding the B7 base pins is 102 mm tall.
References: Datasheet. Type CV1698 was first introduced in 1946.
