The 12AT7WA is a special quality version of the ECC81 VHF double triode.
See Also the Brimar 6060 and/or the Mullard M8162.
These valves are useful for RF stages, oscillators and frequency multipliers.
The Brimar valve seen end on to the anodes.
This image is of a Mullard valve. The two triode sections are mounted with a gap to minimise cross interference this gap is greater than the Brimar version.
This Mullard valve is just marked M8162 on the front.
A close-up of a single section. The grid can be seen to be sited close to the cathode as is required to achieve a good value of mutual conductance.
The reverse has the CV type reference.
The thin glass tube envelope is 21 mm in diameter and excluding the B9A base pins, is 50 mm long.
Reference: Data-sheet. Type 12AT7WA was first introduced in 1961. See also1961 adverts.