On 2017/11/09 8:14 AM, bitrex wrote:
Not exactly a sophisticated piece of test equipment, but lets you eject
bad metal enclosure tubes early:

https://www.dropbox.com/s/m5b4ogl4pqn8tu1/IMG_20171109_110954264.jpg?dl=0

(all the metal tubes in the 1935 table radio passed)

Can you not take the photo in daylight? Could barely make out the
outline of the tester.

I assume it is a go/no-go style, and perhaps verifies if the filaments
are good. Can't imagine it doing much else...

Of course, one can tell if the filaments are good if the tube warms up
in the set, so if that is all it is then it is an early audio-phool tool.

John