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The CV2901 is the UK service designation for the low noise audio amplifier pentode EF86 (Mullard) or Z729 (M-OV). The EF86 design is anti-microphonic. In use it is recommended that it is fitted into a vibration resistant base formed by isolated the base from the metal skirt by a synthetic rubber mount.

This exhibit is an import and carries the term Foreign in place of the maker.

See also CV4086 for the flying lead version.

Looking along the grid axis through the gap in the outer screen. The latter is made from perforated and expanded sheet. The three grids are visible and the method of securing the wire to the supports is clear to see. This was known as the notch and peen system where a cutting wheel opened a depression in the support that the winding would sit within. The metal forced up by the notch knife wheel was then pressed down over the wire by the peening roller.

The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins, is 47 mm tall.

References: Data-sheet & ¹⁰⁴⁰. Type CV2901 was first introduced in 1954. See also 1954 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.