New-Old-Stock (NOS) tube.

The 3A4 is designed for use in compact, lightweight, portable equipment. The relatively large filament employed in the 3A4 enables it to supply the high peak currents required in RF power applications. In RF amplifier service the 3A4 will deliver a power output of about 1.2 watts at 10 megacycles. It is recommended that no material be permitted to obstruct the hole in the base socket as this type may be manufactured with the exhaust-tube tip at the base end.