Type CV628 (commercially the 811) is an HF/VHF transmitting triode rated for operation up to 60 MHz and therefore at one time widely used in military and professional applications at frequencies which other HF types cannot quite reach.
This Type was a popular valve on the War Surplus market during the late 1940s and early 1950s.
The data given is for Class C operation. The control grid current can be up to 35 mA. The overall rating is high for a valve of this size but, slightly de-rated, very suitable for amateur use in the higher frequency bands.
The /J identifies the maker as STC, Crewkerne, pre Jan 1946. However, the actual maker was RCA.
The ceramic insulators indicate a high maximum anode voltage rating.
The base cap has the commercial 811 plus the USA procurement code of VT-217.On the glass is a feint octagon with 811 inside and also on the base cap is RCA.
The top ceramic insulator showing the filament tension springs. The springs end in hooks that hold the top of the two inverted V filaments. The control grid is close wound.
The classic envelope is 61 mm in diameter and, excluding the UX4 base pins, is 149 mm tall.
