The CV585 is an HF pentode and identical to the commercial 6C6.
The data sheet says the 6C6 design is very close to the 6J7G with the exception of the inter electrode capacitances. The 6C6 is a general purpose amplifier valve but the close similarities with the 6J7 indicate a good linear characteristic and good suitability for early stage audio amplification.
The 6C6 with an octagonal border suggests that the original - or part of it - was American made. The base proclaims Brimar as the maker and Made in England. I just wonder just how much was made in the UK.
The top screen with the three grids supports exposed. The control grid connects to the top cap.
The classic envelope is 37 mm in diameter, and excluding the UX6 base pins is 104 mm tall.
