The 6AAS8 is a diode and sharp cut-off pentode. The pentode is a voltage amplifier with a 2.5 Watt anode dissipation. Suggested uses include: IF amplifier, Video Amplifier and AGC amplifier. In the latter function the diode would be the AGC rectifier.
The heater current rating of 450 mA indicates use within domestic television receivers.
The Sylvania name and Made in USA.
The anode has two working faces joined by two straps. Within is the bright beam plates - construction is as beam tetrode.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 48 mm tall.
Reference: Data-sheet. Type 6AS8 was first introduced in 1954. See also1954 adverts.