The CV580 (commercially the 6A8GT) is a triode heptode frequency changer. The oscillator is required to generate 20 Volts pk-pk.
The KB/T identifies this valve as being made to specification K1001 or K1006, the B denotes qualification by a UK authority and the T identifies the maker as British Tungsram, Tottenham.
The Tungsram name, Made in England and the 6A8GT Type designation.
The outer bright anode hides most of the details.
The top mica. The signal grid on the left connects to the top cap. The pair of screen grids are connected together with tape at the top of the supports.
A closer view.
The wide glass tube envelope is 29 mm in diameter and, excluding the IO base pins, is 72 mm tall.
