The 12AW6 dates from 1947 and is a voltage amplifier pentode.

The RCA identification. Few constructional details are visible.

The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 46 mm tall. Type 12AW6 was first introduced^¶ in 1947.

 
Pin Connections

B7G	1	2	3	4	5	6	7
	g1	k	h	h	a	g2	g3

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	12.6	0.15	300	150	-8	7.0	2.0	0.3M	5.0

Thanks to Frank Philipse for supplying the above PDF datasheet