New-Old-Stock (NOS) tube.

The 5749 is a miniature remote-cutoff pentode intended for use as a high-gain radio frequency or intermediate-frequency amplifier. Its remote-cutoff characteristic makes it especially suitable for use in circuits to which it is desired to apply automatic-gain-control. Features include low grid-plate capacitance and relatively high transconductance. The 5749 is a special-quality tube intended for use in critical industrial and military applications in which operational dependability is of primary importance. Features of the tube include a high degree of mechanical strength and a heater-cathode construction capable of withstanding many thousand cycles of intermittent operation. When used in on-off control applications, the tube will maintain its emission capabilities after long periods of operation under cutoff conditions.