Price is for 1 NOS tube with box. Produced in Hamburg, Germany and branded for Philips. Construction with O-getter, silver mesh plates. Identical etched codes: 8Y4 D3F1
Tested VERY STRONG as follow:
Ia = 4.1 mA | S = 2.2 mA/V
Tested under: Uf=6.3V | Ua=250V | Ug2=140V | Ug1=-2.0V
Where 100% is Ia=3.0mA and S=1.9mA/V