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The Type 45 is a directly heated audio output triode. This exhibit is from a late production run and is housed in a classic envelope.

See also 45 for the original balloon production.

This enlargement shows details of the construction. The vertical wires are the supports for the filament tensioning springs. The filament wire and the grid wire can be seen below the anode.

Here we have the original box for this valve.

The production of the 45 ended in around 1932 but has recently been put back in production as it has a well deserved reputation for good audio fidelity.

Many thanks to Simon Balderson for donating these images and valve details.

The classic envelope is 46 mm in diameter, and excluding the UX4 base pins is 103 mm tall.

References: Data-sheet & ³⁰⁰². Type 45 was first introduced in 1929. See also 1929 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.