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The W77 is a miniature variable μ pentode designed to operate at HF as radio frequency amplifiers as well as intermediate frequency amplifiers.

The direct equivalence between the W77 and the CV131 is made clear.

The MWT brand is added with a paper sticker on this M-OV valve.

The wire grids can be glimpsed through the notches in the bright anode..

The thin glass tube envelope is 18 mm in diameter and excluding the B7G base pins, is 47 mm long.

References: Data-sheet & ¹⁰⁴⁰. Type W77 was first introduced in 1949. See also 1949 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.