Summary

The 57 was a sharp cut-off pentode designed for use as an audio and RF amplifier, also used as a biased detector and autodyne converter.
It has a 2.5 volt indirectly heated cathode.
The most popular valve line-up for Australian superheterodyne receivers in 1933 was 57 converter, 58 IFamplifier, 57 biased (anode bend) detector, 47 output valve and 80 rectifier. This line-up remained in use by some manufacturers until 1935.
This valve must have been manufactured in or after 1936 because it carries AWV's excise mark.
Manufacturer: Amalgamated Wireless Valve Co., Sydney, NSW.

Physical Description

Shouldered bulb with top cap on six pin base.

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