The CV1510 is a single beam tetrode and is an early all glass envelope design. The maximum full power frequency is 60 MHz. The output is modest and the dissipation high in relation to the Class C output power and this is consistent with early VHF devices.
The CV309 is the CV1510 with plated pins and a maximum full power output frequency of 150 MHz.
The screening is both above and below the mica discs. The key on the base spigot ensures correct orientation in the valve-holder.
The circular top screen and within can be seen the flattened oval cathode tube. The pressed glass base sealing the internal and external parts of the pins.
The wide glass tube envelope is 32 mm in diameter, and excluding the B9G base pins is 59 mm tall.
References: Data-sheet & 1040. Type CV1510 was first introduced in 1947. See also1947 adverts.