Price is for 4 NOS tube that came sealed in styrofoam box. Tubes were first opened just before I test it and took pictures. Made in Heerlen, Netherlands and branded as Valvo an Philips. With etched codes WK6 𝛥8F and WK6 𝛥8D. Construction with single D-getter, pinched waist and gold pins.
Tested VERY STRONG as follow:
Tube 1:
Ia1 = 6.2 mA | S1 = 2.6 mA/V | Ri1 = 12.0 kOhm | μ1 = 31.2
Ia2 = 6.8 mA | S2 = 2.8 mA/V | Ri2 = 11.1 kOhm | μ2 = 31.1
Tube 2:
Ia1 = 6.1 mA | S1 = 2.6 mA/V | Ri1 = 12.3 kOhm | μ1 = 32.0
Ia2 = 6.2 mA | S2 = 2.6 mA/V | Ri2 = 12.1 kOhm | μ2 = 31.5
Tube 3:
Ia1 = 6.0 mA | S1 = 2.5 mA/V | Ri1 = 12.2 kOhm | μ1 = 30.5
Ia2 = 5.4 mA | S2 = 2.4 mA/V | Ri2 = 13.2 kOhm | μ2 = 31.7
Tube 4:
Ia1 = 6.6 mA | S1 = 2.7 mA/V | Ri1 = 11.6 kOhm | μ1 = 31.3
Ia2 = 6.4 mA | S2 = 2.6 mA/V | Ri2 = 12.0 kOhm | μ2 = 31.2
Test under: Uf = 12.6V, Ua = 250V, Ug = -5.5V
Where good starts from Ia=4.3mA and 100% is Ia=6.0mA
Shipping will be Airmail registered with tracing number. Other shipping methods available on request.