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NT46 or NT57 silica triode valve from the early ground radar transmitter type TF3, 1936

1936
NT46 or NT57 silica triode valve from the early ground radar transmitter type TF3, 1936. In wooden crate. Silica (fused quartz) had been used for the envelopes of high-power valves since about 1918, particularly for naval transmitters. Silica softens at a much higher temperature than glass, so the valves could dissipate more power. The valve had smaller interelectrode capacitance and higher emission than the earlier design of silica valve it replaced and it was found possible to increase the emission still further by using a filament voltage 10% above the rated value. A pair of these valves could produce peak power outputs of up to 40kW.

NT46 or NT57 silica triode valve from the early ground radar transmitter type TF3

1936
NT46 or NT57 silica triode valve from the early ground radar transmitter type TF3, 1936. In wooden crate. Silica (fused quartz) had been used for the envelopes of high-power valves since about 1918, particularly for naval transmitters. Silica softens at a much higher temperature than glass, so the valves could dissipate more power. The valve had smaller interelectrode capacitance and higher emission than the earlier design of silica valve it replaced and it was found possible to increase the emission still further by using a filament voltage 10% above the rated value. A pair of these valves could produce peak power outputs of up to 40kW.

NT46 or NT57 silica triode valve from the early ground radar transmitter type TF3

1936