Micropup triode: air cooled with thoriated tungsten filament. The prototype was the M-OV E1265 and the old UK Navy designation was NT97.
The anode connects to the outside and has the brass cooling fins. The re-entrant glass end houses the control grid connection. This takes the form of threaded copper.
The filament end. The filament is helical but not visible in this image. Both supports originate from the same end.
The control grid helical winding is supported at one end only.
The glass tube envelope is 24 mm in diameter and, including the base pins, is 107 mm tall.
