The NT97 is an air cooled UHF power triode with thoriated tungsten filament. The prototype was E1265. Later it became known as the CV1254.
These oscillator valves were known as Micropup valves. The finned anode would be at earth potential with the filament held negative. The maximum anode voltage was 9 kV and the peak cathode current was 17.5 Amps. The anode was designed to dissipate 100 Watts.
The control grid connection is made via a re-entrant glass end.
The centre of the grid connector is threaded.
The filament connections are made via the attached wires. This valve is unused and the fold of the wires is as they were packed. The unused central lead connects to the centre of the filament. The helical grid and filament can just be seen through the distorting effect of the thick glass.
A slightly better view of the filament and control grid.
The wide glass tube envelope is 25 mm in diameter and, including the base pins, is 105 mm tall.