The CV665 lettering has been overprinted in white on the original valve made my RCA.
The valve is electrically equivalent to 'acorn' type 956 but re-engineered to B7G dimensions. The valve is classed as a vari-mu UHF receiving pentode.
The design dates to 1943 but B7G based valves were not made in the UK until the late 1940's.
Visually it can be seen that inside the miniature envelope there is a small volume taken up with the electrode assembly.
Here the original Type designation is seen. The CV665 is thus equal to the commercial 9003. It is a true pentode with three wire grids visible. The suppressor grid is connected to the cathode at the base of the g3 support rod.
This shows just how small the pentode actually is given the glass envelope is 18 mm wide.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 37 mm tall.
Reference: Data-sheet. Type CV665 was first introduced in 1943. See also1943 adverts.
