All tube operating points below are by no means definitive good sound recipe for your particulate tube project. Lowest THD point is not necessary best sounding one and there is always some variance even in a NOS tube batch from the same manufacturer!  Below information is only useful as a general starting point and is ment to get you in a ballpark when no measurement equipment is available.

Lowest THD operating point spectrum

5mA, -3.48V BIAS, 263 Va

Recommended operating point spectrum

7.5mA, -2.95V BIAS, 263 Va

Other operating points

10mA, -2.46V BIAS, 265 Va
 3mA, -4.2V BIAS, 270 Va

Traced plate curves

THD statistics


Pretty high THD. More suitable for RF. Available for sale.

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