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Stamping of anodes

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The pictures in this article come from the BVWS DVD of the 1950s Mullard film.

Most small valves had anodes made from Nickel sheet. Nickel is a silvery white metal that has a melting point of 1455°C enabling it to operate at high temperature within the valve. To improve the anode's ability to radiate away the heat generated from the bombardment of energetic electrons it can also be carbonised to give it a blackened surface.

Typical anode forming machine

Anode's were formed from sheet Nickel on a single machine. In some machines the sheet was stamped to shape, bent as required and even closed seams made for anode's that completely enclosed the grids. The EF80, as a low power valve had a simple open anode.

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