Summary

Transmitting triode in a fused silica bulb. The use of silica for high powered valves was developed by Mullard in England in the 1920s. The bulbs were handmade and very expensive but allowed much higher operating temperatures than ordinary glass which made them useful where a compact bulb was necessary. This valve was used in the type 286PQ shipboard radar.

Physical Description

Fused silica bulb consisting of a cylindrical part which forms the main part of the bulb and a domed section closing it with a raised fused joint between them. There are two leads carrying the filament connections fitted to the domed section and two pairs of leads carrying the grid and anode connections at the top of the cylindrical section. The inscriptions have been formed by a thread of silica fused into the surface of the bulb. The anode appears to have been made from a ribbon of Molybdenum metal wound around a former of wires like a cane basket. The pins are terminated in flexible leads.

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