The 12AT7WA is a special quality version of the ECC81 VHF double triode and this is an unbranded example. The envelope has the Type designation etched into it plus a printed ECC81 SQ.
These valves are useful for RF stages, oscillators and frequency multipliers.
The twin triodes separated by space and not by a screen. Note the double mica discs, this double thickness was found to be effective in reducing the effects of vibration.
Each anode is folded into a box with a side flange. The flanges are then stitched together. The outer surface has been treated with carbon to aid heat radiation.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins, is 48 mm long.
Reference: Data-sheet. Type 12AT7WA was first introduced in 1961. See also1961 adverts.
