The CV417 is a miniature single triode for use as a grounded grid amplifier, and thus at high frequency.
This type of valve was designed for RF applications at VHF up to a maximum frequency of 250 MHz. These would include radio, television and radar. The equivalent noise resistance was given as 400 Ohms. The M8099 special quality version was made for critical applications the commercial Types are 6AQ4 & EC91. The latter being the prototype for the CV417.
The triode is in the centre and the outer rods are supports.
The triode face view. The control grid is fitted with heat sink fins. The cathode is rectangular.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 47 mm tall.