The PC97 is a frame grid RF amplifier triode. It has a high mutual conductance of 13.0[k[mA/V and could be used as a signal pre-amplifier. Its design use would be in domestic television receivers.
The PC97 has an unusually low grid to anode capacitance of about 0.5 pF. This low capacitance is obtained by using a special shield between grid and anode in conjunction with a shaped anode. Because of this shield that is in place except in the active cathode to anode region these valves are also known as Beam Triodes. An additional benefit is that the neutralising capacitor can be connected to ground on one side. The PC95 also uses this construction technique.
This image shows the reentrant anode. Only the flat end acts as the working face, the rest of the metal is a heat sink. The inner shield can be seen above the top mica.
The end of the anode looking along the grid axis.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 46 mm tall.
References: Datasheet & 1040. Type PC97 was first introduced in 1961.