These tubes are selected from a batch and have:
- within 5% balanced sections per tube
- within 5% match of sections for the pair
These tubes are tested ok for shorts and gas.
We test our tubes on a AVO Mark III tube tester and if required a computerized curver tracer (uTracer)
For older tubes we use a Hickok I-177.
settings: Va = 250V, Vg = -4.6V , Vh = 6.3 V
a good (NOS) tube test for: Gm = 2.3mA/V and Ia 6.0 mA
Tube 6: Ia1 = 7.00 Ia2 = 6.78
Gm1 = 2.3 Gm2 = 2.3
Tube 8: Ia1 = 6.90 Ia2 = 7.10
Gm1 = 2.25 Gm2 = 2.35
- General availability
- Very Rare