Summary

General purpose triode, introduced in 1926. One of the Philips "Miniwatt" series, so called because of their low filament consumption. Similar characteristics to a 201A but used about 20% of the filament power. 4 volt directly heated cathode.
In the 1920s many radios of American origin and normally fitted with 201As were fitted with A409 or A609 valves by their owners in Australia to give greatly improved filament ("A") battery life.
Manufacturer: Philips, Holland.

Physical Description

Conical bulb (sectioned) on 4 pin UX style basel, mounted on display block.

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