The CV1950 (commercially the 6L7G) 6L7 is a VHF pentagrid converter (mixer) aimed at ensuring maximum isolation between oscillator and signal, and to provide a mixer which is efficient at VHF where stable oscillation would otherwise require a separate VHF oscillator triode.
For applications where a self-oscillating mixer (i.e., pentagrid converter) could provide adequate performance there were other Octal types specifically designed for the purpose. The trend was towards the triode hexode that removed the tendency for oscillator 'pulling' on strong signals.
The T probably identifies the maker as British Tungsram, Tottenham.
The internal coating covers most of the envelope.
At the top can be seen the wire grids with the two screening grids connected together at the top of the supports. The control grid connects to the top cap.
The top mica and grid supports.
A closer view showing the round oxide coated cathode.
The classic envelope is 39 mm in diameter and, excluding the IO base pins, is 100 mm tall.
References: Data-sheet, 1043 & 3002. Type CV1950 was first introduced in 1936. See also1936 adverts.
