The EC8010 is a special quality UHF amplifier triode for use up to 1 GHz. The design functions are RF amplification and as an oscillator. The design is resistant to shock and vibration and thus this triode would be found in military and airborne applications.
The anode is blackened to assist with heat dissipation. The high anode current of 28 mA for a small signal device is because the noise factor is lower than for a similar device operated at low anode currents.
In this image the right hand side of the frame grid can be seen. At full size the image reveals the individual fine grid wires.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 48 mm tall.
References: Datasheet. Type EC8010 was first introduced in 1968.