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The N150 is a 1940s all glass output pentode.The N150 should only be used with self-bias or semi-automatic bias.

Unlike the first B8A valves that had a metal base cover with locating spigot, this valve has a wider base to the envelope and a locating pip moulded into the glass. It indeed represents the transition point to the final all glass valve. The pins are still equi-spaced in the base and this soon gave way to the B9A and B7G styles that did not require a locating spigot.

The discolouration inside the glass testifies to this exhibit having had a hard service life.

The locating pip and the moulded skirt. The make is unknown but the indented ring between the hard glass base and the soft glass envelope looks like Philips production in the Netherlands.

The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 68 mm tall.

References: Data-sheet & ¹⁰⁴⁰. Type N150 was first introduced in 1948. See also 1948 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.