help identifying a vacuum tube

Question

I recently bought this tube for use in an art project and would like to know what it is and what it was originally used for. Unfortunately, the silkscreen labelling on the glass envelope was worn off and unreadable and there are no other obvious identifying marks on it. The tape measure indicates scale (it's big!). I'd also like to find a source for more like this, since it has generated a lot of interest sitting on the shelf in my shop.

Answer 1

This looks like a JAN-CTL-5948A, found via images within the search results for "huge vacuum tube".

According to the linked site (from which the picture is also taken):

The primary application of this tube is in high power, high voltage radar modulators. The 5948A is capable of supplying 12 megawatt pulses in this service.

The datasheet indicates that it's a bit beyond a typical vacuum tube:

The special features of the 5948A include an internal hydrogen-reservoir capable of producing a wide range of hydrogen pressure […]

Some online listings title this as a "Industrial High Power Early Warning Radar Military Hydrogen Thyratron Tube". I couldn't recommend trying to get it working ;-)

Answer 2

If the diameter of the glass base (just above the metal mounting bracket) is approx 5 ", its a type 5948 or 5948A, If the diameter o the glass base( just above the metal mounting ring) is apprx 7", its a type 1247. Both tubes are pulse modulators for radar with built in hydrogen replenishment.So they are nothing more than a high power switch. The 5948 will switch 12 Mw and the 1247 will switch 30Mw. Certainly the latter will generate x-rays with 30KV on the plate. They are of no use in amateur service. The filament of the 1247 takes 5V @40amps.pretty costly transformer for playing. I can tell you the filament is highly shielded and you can't see it when the filamen is lit. Technical specs for the 1247 are contained in the February 1953 edition of "Electronics"magazine.