(!!) (slightly microphonic) B309=12AT7 GEC UK black plates “”D”” getter NOS 1950”s (9.6/10.8ma)

1 slightly micophonic low noise tube) B309=12AT7 GEC UK black plates “”D”” getter NOS 1950”s

9.6ma Gm=5400

10.8ma Gm=5700

– similar build to 12AT7 Brimar black plates 1950”s