“Lodge” Rectifier Valve

Ref. H1

This tube was designed by Sir Oliver Lodge and is English made. It dates back to the early years of the last century.

Technical specifications

• 5 1/2” (14cms) bulb.
• Total weight: 205 Grams (7 oz.).

One electrode is a long and wide aluminum spiral, connected to a side terminal of the bulb, while the other is a small metal (probably Iron) rod in the distal part of the narrow stem, in the axis of the thin internal copper shielding protecting the surrounding glass (see X-ray picture).

Such tubes usually contain air at a very low pressure, and the rectification process is due to the important size asymmetry of the electrodes, with the current flowing much more easily in one direction than in the opposite one. 

Note the looped platinum wire external connections of the electrodes, as usually found in very early X-ray tubes. Later makes of this rectifier are equipped with dome-shaped brass terminals.

The round mark on the glass bulb reads “Sir O.LODGE *Patent*240”.