Cylindrical Focus Tube






10 (25 cms) long, 1.5 (37 mms) diameter, 3 electrode tube.


Aluminium rod anode. Concave aluminium cathode. Thin platinum anti-cathode target deformed by the intense heat generated by the impact of the electron beam.


Looped platinum wire external connections.


Glass discoloration on the anode side of the tube due to use.


Unknown make. Undated, but judging from the thin bare square-shaped platinum target it should be of about the same period as the Jackson focus tube (1896). In later makes of tubes the thin platinum target is round in shape and embedded in a metal support (e.g. the bulbar focus tube).


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