The CV88 is a UHF triode for grounded grid circuits. The operating frequency is around 600 MHz. The prototype was the S28A.
The grid connection is brought out through the glass as a copper disc. This is then clamped between two metal plates 54 x 57 mm. Looking closely the plates are separated from the copper disc by thin mica sheets that isolate the plates from the disc. The tower on the right has an outer grub screw - probably ceramic - and an inner metal grub screw. The grid connection is made to the copper disc by a spring that the inner screw touches. The connecting lead passes through the hole in the two screws and is clamped between them.
The re-entrant end has the evacuation pip and the copper anode directly exposed by the glass/metal seal. The anode connection can, therefore, be of substantial diameter and offer good heat removal. Even so the maximum anode dissipation is only two Watts.
The heater/cathode end. The central heater wire is bent in this exhibit. The other heater connection is tied to the cathode and is deep within the envelope.
The bright rectangular cathode is coated on one side only. At each end four grid wires are still present. For the rest of the length of the cathode the grid is single sided.
The wide glass tube envelope is 27 mm in diameter and, excluding the base pin, is 75 mm tall.