The CV3995 (commercially the 6CB6) is a sharp cut-off amplifier valve designed to operate at 20 MHz and above in IF amplifier circuits. VHF television is one application.
This exhibit was made in Canada but there is no indication of the company.
A clear example of the beam tetrode. Either side of the cathode are the inner grids, beam plates to capture any secondary electrons from the anode and then the anode plates themselves.
A closer view.
The envelope is 18 mm in diameter and, excluding the B7G base pins, is 47 mm tall.
