The CV4023 is a special quality version of the EF94 RF pentode. The American Type designation would be the 6AU6WA. CV4023 has a useful frequency range up to 50 MHz.
The three wire grids can be glimpsed through the notches in the anode sides.
The CSF logo. The Made in France lettering is in English as this is a UK service valve.
The thin glass tube envelope is 18 mm in diameter and excluding the B7G base pins, is 46 mm tall.
