The PC900 is a miniature VHF amplifier triode for use as an RF amplifier in television receivers. It is low impedance and has a high mutual conductance. This is partly achieved by a very low cathode to grid spacing. The anode is made of two rectangular channels, one either side of the cathode. The beam plates form the electrons into two beams.
On the right is one of the anode sections. The bulk metal is for heat dissipation while the small centre rectangle projects back close to the grid and is the working area of the triode for low capacitance.
Looking directly at the anode showing the working face close to the centre of the valve.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 33 mm tall.
References: Data-sheet, 3002 & 1040. Type PC900 was first introduced in 1963. See also1963 adverts.