Six-Sixty S.S.2a L.F.

2-volt triode

Six-Sixty S.S.2a L.F.

This triode has an unusual mottled green bakelite base. Made on 23^rd. August, 1927^*. Possibly a below specification Mullard PM2A, but it does not appear in any of the 1930s equivalent lists I have. It is certainly an azide process valve. It is rated for a maximum anode voltage of 100V versus the 150V rating of the Mullard valve.

^*The date is engraved on the envelope.