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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 23rd. 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.