The A442 along with the A642 were the first screen-grid valves made by Philips. It was introduced in 1927 and was probably one of the first valves of this type to be available in Australia.

The screen-grid valve was a tetrode designed to minimise the capacitive coupling between the plate and the control grid making possible high stage gain without instability in radio frequency circuits.

Physical Description

Conical glass bulb, with top cap (detached), and American style 4 pin (UX) brown Bakelite base. Mounted on display block with a similar valve with the bulb removed.

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