The CV1219 is an audio power valve. The prototypes were the M-OV DA100 and the Mullard MZ1-100. The old service code was NT36. This exhibit has lost all markings but dimensionally and visually matches the CV1219.
Unlike the original DA100 (NT36) this later implementation is smaller for the same anode dissipation and uses multiple side flanges to obtain the required radiating surface area.
Looking along the grid axis showing the rounded end to the anode.
The reverse also has three flanges.
There are ceramic insulators top and bottom. Here at the top there is a mica sheet. The helical springs used to tension the filament clamp tape at the top that terminates in a hook. The filament tape passes over a small open cylinder that the hook sits in. The control grid wire looks to be copper.
Another view.
The classic envelope is 65 mm in diameter and, excluding the L4 base pins, is 165 mm tall.
