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Experimental Phototube, maker unknown
Tube photo-électrique expérimental, fabricant inconnu
Experimentelle Fotoröhre, Hersteller unbekannt

This tube was sold by FAIR RADIO SALES Co., Inc. (Lima, Ohio). Some similar tubes from the same source have a slighly different design (xp001, xp002, xp037).

The end window has some semi-transparent coating; two radial pins connect to a heavily metallized deposited ring at the face.

The four lateral tubulation ports could have been used for the introduction of small evaporation sources to form the photosensitive layer.

Note the curious spot pattern on the faceplate. They are perfectly circular, and disposed randomly. Their purpose, and how they were obtained, are unknown.

A filament, partially coated, is inserted into a metal cylinder. Its resistance measures about 4 Ω.

Another collector has a similar tube with a paper sticker on it giving some sensitivity specs: “120 mA/L, 10/23/68”.

Three of the “long electrodes” have electrical connections at each end and are made of a folded thin sheet spotwelded into a tube-like structure. They would appear to carry a payload of material which could be resistively heated.

These tubes have defied the perspicacity of many vacuum tube specialists and collectors.


Experimental Phototube, maker unknown

Hauteur • Height • Höhe : 123 mm • 4" 7/8
Diamètre • Diameter • Durchmesser : 56 mm • 2" 1/4

Experimental Phototube, maker unknown

Experimental Phototube, maker unknown

Experimental Phototube, maker unknown

Experimental Phototube, maker unknown


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