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This Cossor bright emitter triode is a P1. The valve is not
gettered and probably dates from before the introduction of the
stamp regulations on Nov 1st., 1922.
The unusual cup anode is believed to be a way of avoiding a Marconi
patent on cylindrical anodes.
The box is sturdily constructed from cardboard and
the valve is protected by horsehair wadding above and below.
The base is typical of early 1920's valves, having split rather than spring pins and the electrode connection made by soldering to the outside of the pins just below the base.
Later examples were on this rather pretty orange red bakelite base, still using the same wiring method.
Below is a picture of a P1 from the 1935-6 A.C. Cossor Valve Manual, when the P1 was already a piece of history and considered important enough to the company to warrant a picture and a brief description. More history of the Cossor company.
This page last modified by AJC on Friday, 26-Mar-2010